[Federal Register Volume 71, Number 2 (Wednesday, January 4, 2006)]
[Rules and Regulations]
[Pages 388-493]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 06-3]



[[Page 387]]

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Part II





Environmental Protection Agency





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40 CFR Parts 9, 141, and 142



National Primary Drinking Water Regulations: Stage 2 Disinfectants and 
Disinfection Byproducts Rule; Final Rule

Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / 
Rules and Regulations

[[Page 388]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 9, 141, and 142

[EPA-HQ-OW-2002-0043; FRL-8012-1]
RIN 2040-AD38


National Primary Drinking Water Regulations: Stage 2 
Disinfectants and Disinfection Byproducts Rule

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is promulgating 
today's final rule, the Stage 2 Disinfectants and Disinfection 
Byproducts Rule (DBPR), to provide for increased protection against the 
potential risks for cancer and reproductive and developmental health 
effects associated with disinfection byproducts (DBPs). The final Stage 
2 DBPR contains maximum contaminant level goals for chloroform, 
monochloroacetic acid and trichloroacetic acid; National Primary 
Drinking Water Regulations, which consist of maximum contaminant levels 
(MCLs) and monitoring, reporting, and public notification requirements 
for total trihalomethanes (TTHM) and haloacetic acids (HAA5); and 
revisions to the reduced monitoring requirements for bromate. This 
document also specifies the best available technologies for the final 
MCLs. EPA is also approving additional analytical methods for the 
determination of disinfectants and DBPs in drinking water. EPA believes 
the Stage 2 DBPR will reduce the potential risks of cancer and 
reproductive and developmental health effects associated with DBPs by 
reducing peak and average levels of DBPs in drinking water supplies.
    The Stage 2 DBPR applies to public water systems (PWSs) that are 
community water systems (CWSs) or nontransient noncommunity water 
systems (NTNCWs) that add a primary or residual disinfectant other than 
ultraviolet light or deliver water that has been treated with a primary 
or residual disinfectant other than ultraviolet light.
    This rule also makes minor corrections to drinking water 
regulations, specifically the Public Notification tables. New endnotes 
were added to these tables in recent rulemakings; however, the 
corresponding footnote numbering in the tables was not changed. In 
addition, this rule makes a minor correction to the Stage 1 
Disinfectants and Disinfection Byproducts Rule by replacing a sentence 
that was inadvertently removed.

DATES: This final rule is effective on March 6, 2006. For judicial 
review purposes, this final rule is promulgated as January 4, 2006. The 
incorporation by reference of certain publications listed in the rule 
is approved by the Director of the Federal Register as of March 6, 
2006.

ADDRESSES: EPA has established a docket for this action under Docket ID 
No. EPA-HQ-OW-2002-0043. All documents in the docket are listed on the 
http://www.regulations.gov Web site.
    Although listed in the index, some information is not publicly 
available, e.g., CBI or other information whose disclosure is 
restricted by statute. Certain other material, such as copyrighted 
material, is not placed on the Internet and will be publicly available 
only in hard copy form.
    Publicly available docket materials are available either 
electronically through http://www.regulations.gov or in hard copy at 
the Water Docket, EPA/DC, EPA West, Room B102, 1301 Constitution Ave., 
NW., Washington, DC. The Public Reading Room is open from 10 a.m. to 4 
p.m., Monday through Friday, excluding legal holidays. The telephone 
number for the Public Reading Room is (202) 566-1744, and the telephone 
number for the Water Docket is (202) 566-2426.

FOR FURTHER INFORMATION CONTACT: For technical inquiries, contact Tom 
Grubbs, Standards and Risk Management Division, Office of Ground Water 
and Drinking Water (MC 4607M), Environmental Protection Agency, 1200 
Pennsylvania Ave., NW., Washington, DC 20460; telephone number: (202) 
564-5262; fax number: (202) 564-3767; e-mail address: 
grubbs.thomas@epa.gov. For general information, contact the Safe 
Drinking Water Hotline, Telephone (800) 426-4791. The Safe Drinking 
Water Hotline is open Monday through Friday, excluding legal holidays, 
from 10 a.m. to 4 p.m. Eastern Time.

SUPPLEMENTARY INFORMATION:

I. General Information

A. Does This Action Apply to Me?

    Entities potentially regulated by the Stage 2 DBPR are community 
and nontransient noncommunity water systems that add a primary or 
residual disinfectant other than ultraviolet light or deliver water 
that has been treated with a primary or residual disinfectant other 
than ultraviolet light. Regulated categories and entities are 
identified in the following chart.

------------------------------------------------------------------------
                                                                Examples
                                                                   of
                           Category                            regulated
                                                                entities
------------------------------------------------------------------------
Industry.....................................................  Community
                                                                 and
                                                               nontransi
                                                                 ent
                                                               noncommun
                                                               ity water
                                                               systems
                                                               that use
                                                               a primary
                                                                  or
                                                               residual
                                                               disinfect
                                                               ant other
                                                                than
                                                               ultraviol
                                                               et light
                                                                  or
                                                               deliver
                                                               water
                                                               that has
                                                                been
                                                               treated
                                                               with a
                                                               primary
                                                                  or
                                                               residual
                                                               disinfect
                                                               ant other
                                                                than
                                                               ultraviol
                                                               et light.
State, Local, Tribal, or Federal Governments.................  Community
                                                                 and
                                                               nontransi
                                                                 ent
                                                               noncommun
                                                               ity water
                                                               systems
                                                               that use
                                                               a primary
                                                                  or
                                                               residual
                                                               disinfect
                                                               ant other
                                                                than
                                                               ultraviol
                                                               et light
                                                                  or
                                                               deliver
                                                               water
                                                               that has
                                                                been
                                                               treated
                                                               with a
                                                               primary
                                                                  or
                                                               residual
                                                               disinfect
                                                               ant other
                                                                than
                                                               ultraviol
                                                               et light.
------------------------------------------------------------------------

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be regulated by this 
action. This table lists the types of entities that EPA is now aware 
could potentially be regulated by this action. Other types of entities 
not listed in the table could also be regulated. To determine whether 
your facility is regulated by this action, you should carefully examine 
the definition of ``public water system'' in Sec.  141.2 and the 
section entitled ``coverage'' (Sec.  141.3) in Title 40 of the Code of 
Federal Regulations and applicability criteria in Sec.  141.600 and 
141.620 of today's proposal. If you have questions regarding the 
applicability of this action to a particular entity, contact the person 
listed in the preceding FOR FURTHER INFORMATION CONTACT section.

B. How Can I Get Copies of This Document and Other Related Information?

    See the ADDRESSES section for information on how to receive a copy 
of this document and related information.

Regional contacts:
I. Kevin Reilly, Water Supply Section, JFK Federal Bldg., Room 203, 
Boston, MA 02203, (617) 565-3616.
II. Michael Lowy, Water Supply Section, 290 Broadway, 24th Floor, New

[[Page 389]]

York, NY 10007-1866, (212) 637-3830.
III. Jason Gambatese, Drinking Water Section (3WM41), 1650 Arch Street, 
Philadelphia, PA 19103-2029, (215) 814-5759.
IV. Robert Burns, Drinking Water Section, 61 Forsyth Street SW., 
Atlanta, GA 30303, (404) 562-9456.
V. Miguel Del Toral, Water Supply Section, 77 W. Jackson Blvd., 
Chicago, IL 60604, (312) 886-5253.
VI. Blake L. Atkins, Drinking Water Section, 1445 Ross Avenue, Dallas, 
TX 75202, (214) 665-2297.
VII. Douglas J. Brune, Drinking Water Management Branch, 901 North 5th 
Street, Kansas City, KS 66101, (800) 233-0425.
VIII. Bob Clement, Public Water Supply Section (8P2-W-MS), 999 18th 
Street, Suite 500, Denver, CO 80202-2466, (303) 312-6653.
IX. Bruce Macler, Water Supply Section, 75 Hawthorne Street, San 
Francisco, CA 94105, (415) 972-3569.
X. Wendy Marshall, Drinking Water Unit, 1200 Sixth Avenue (OW-136), 
Seattle, WA 98101, (206) 553-1890.

Abbreviations Used in This Document

ASDWA Association of State Drinking Water Administrators
ASTM American Society for Testing and Materials
AWWA American Water Works Association
AwwaRF American Water Works Association Research Foundation
BAT Best available technology
BCAA Bromochloroacetic acid
BDCM Bromodichloromethane
CDBG Community Development Block Grant
CWS Community water system
DBAA Dibromoacetic acid
DBCM Dibromochloromethane
DBP Disinfection byproduct
DBPR Disinfectants and Disinfection Byproducts Rule
DCAA Dichloroacetic acid
EA Economic analysis
EC Enhanced coagulation
EDA Ethylenediamine
EPA United States Environmental Protection Agency
ESWTR Enhanced Surface Water Treatment Rule
FACA Federal Advisory Committee Act
GAC Granular activated carbon
GC/ECD Gas chromatography using electron capture detection
GWR Ground Water Rule
GWUDI Ground water under the direct influence of surface water
HAA5 Haloacetic acids (five) (sum of monochloroacetic acid, 
dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and 
dibromoacetic acid)
HAN Haloacetonitriles (trichloroacetonitrile, dichloroacetonitrile, 
bromochloroacetonitrile, and dibromoacetonitrile)
IC Ion chromatograph
IC/ICP-MS Ion chromatograph coupled to an inductively coupled plasma 
mass spectrometer
IDSE Initial distribution system evaluation
ILSI International Life Sciences Institute
IESWTR Interim Enhanced Surface Water Treatment Rule
IPCS International Programme on Chemical Safety
IRIS Integrated Risk Information System (EPA)
LOAEL Lowest observed adverse effect level
LRAA Locational running annual average
LT1ESTWR Long Term 1 Enhanced Surface Water Treatment Rule
LT2ESTWR Long Term 2 Enhanced Surface Water Treatment Rule
MBAA Monobromoacetic acid
MCAA Monochloroacetic acid
MCL Maximum contaminant level
MCLG Maximum contaminant level goal
M-DBP Microbial and disinfection byproducts mg/L Milligram per liter
MRL Minimum reporting level
MRDL Maximum residual disinfectant level
MRDLG Maximum residual disinfectant level goal
NDMA N-nitrosodimethylamine
NDWAC National Drinking Water Advisory Council
NF Nanofiltration
NOAEL No Observed Adverse Effect Level
NODA Notice of data availability
NPDWR National primary drinking water regulation
NRWA National Rural Water Association
NTNCWS Nontransient noncommunity water system
NTP National Toxicology Program
NTTAA National Technology Transfer and Advancement Act
OMB Office of Management and Budget
PAR Population attributable risk
PE Performance evaluation
PWS Public water system
RAA Running annual average
RFA Regulatory Flexibility Act
RfD Reference dose
RSC Relative source contribution
RUS Rural Utility Service
SAB Science Advisory Board
SBAR Small Business Advisory Review
SBREFA Small Business Regulatory Enforcement Fairness Act
SDWA Safe Drinking Water Act, or the ``Act,'' as amended in 1996
SER Small Entity Representative
SGA Small for gestational age
SUVA Specific ultraviolet absorbance
SWAT Surface Water Analytical Tool
SWTR Surface Water Treatment Rule
TC Total coliforms
TCAA Trichloroacetic acid
TCR Total Coliform Rule
THM Trihalomethane
TOC Total organic carbon
TTHM Total trihalomethanes (sum of four THMs: chloroform, 
bromodichloromethane, dibromochloromethane, and bromoform)
TWG Technical work group
UMRA Unfunded Mandates Reform Act
UV 254 Ultraviolet absorption at 254 nm
VSL Value of Statistical Life
WTP Willingness To Pay

Table of Contents

I. General Information
    A. Does This Action Apply to Me?
    B. How Can I Get Copies of This Document and Other Related 
Information?
II. Summary of the Final Rule
    A. Why is EPA Promulgating the Stage 2 DBPR?
    B. What Does the Stage 2 DBPR Require?
    1. Initial Distribution System Evaluation
    2. Compliance and monitoring requirements
    3. Operational Evaluation Levels
    4. Consecutive systems
    C. Correction of Sec.  141.132
III. Background
    A. Statutory Requirements and Legal Authority
    B. What is the Regulatory History of the Stage 2 DBPR and How 
Were Stakeholders Involved?
    1. Total Trihalomethanes Rule
    2. Stage 1 Disinfectants and Disinfection Byproducts Rule
    3. Stakeholder involvement
    a. Federal Advisory Committee process
    b. Other outreach processes
    C. Public Health Concerns to be Addressed
    1. What are DBPs?
    2. DBP Health Effects
    a. Cancer health effects
    i. Epidemiology
    ii. Toxicology
    b. Reproductive and developmental health effects
    i. Epidemiology
    ii. Toxicology
    c. Conclusions
    D. DBP Occurrence and DBP Control
    1. Occurrence
    2. Treatment
    E. Conclusions for Regulatory Action
IV. Explanation of Today's Action
    A. MCLGs

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    1. Chloroform MCLG
    a. Today's rule
    b. Background and analysis
    c. Summary of major comments
    2. HAA MCLGs: TCAA and MCAA
    a. Today's rule
    b. Background and analysis
    c. Summary of major comments
    B. Consecutive Systems
    1. Today's Rule
    2. Background and analysis
    3. Summary of major comments
    C. LRAA MCLs for TTHM and HAA5
    1. Today's rule
    2. Background and analysis
    3. Summary of major comments
    D. BAT for TTHM and HAA5
    1. Today's rule
    2. Background and analysis
    3. Summary of major comments
    E. Compliance Schedules
    1. Today's rule
    2. Background and analysis
    3. Summary of major comments
    F. Initial Distribution System Evaluation (IDSE)
    1. Today's rule
    a. Applicability
    b. Data collection
    i. Standard monitoring
    ii. System specific study
    iii. 40/30 certification
    c. Implementation
    2. Background and analysis
    a. Standard monitoring
    b. Very small system waivers
    c. 40/30 certifications
    d. System specific studies
    e. Distribution System Schematics
    3. Summary of major comments
    G. Monitoring Requirements and Compliance Determination for TTHM 
and HAA5 MCLs
    1. Today's Rule
    a. IDSE Monitoring
    b. Routine Stage 2 Compliance Monitoring
    i. Reduced monitoring
    ii. Compliance determination
    2. Background and Analysis
    3. Summary of Major Comments
    H. Operational Evaluation Requirements initiated by TTHM and 
HAA5 Levels
    1. Today's rule
    2. Background and analysis
    3. Summary of major comments
    I. MCL, BAT, and Monitoring for Bromate
    1. Today's rule
    2. Background and analysis
    a. Bromate MCL
    b. Criterion for reduced bromate monitoring
    3. Summary of major comments
    J. Public Notice Requirements
    1. Today's rule
    2. Background and analysis
    3. Summary of major comments
    K. Variances and Exemptions
    1. Today's Rule
    2. Background and Analysis
    a. Variances
    b. Affordable Treatment Technologies for Small Systems
    c. Exemptions
    3. Summary of major comments
    L. Requirements for Systems to Use Qualified Operators
    M. System Reporting and Recordkeeping Requirements
    1. Today's rule
    2. Summary of major comments
    N. Approval of Additional Analytical Methods
    1. Today's Rule
    2. Background and Analysis
    O. Laboratory Certification and Approval
    1. PE acceptance criteria
    a. Today's rule
    b. Background and analysis
    c. Summary of major comments
    2. Minimum reporting limits
    a. Today's rule
    b. Background and analysis
    c. Summary of major comments
    P. Other regulatory changes
V. State Implementation
    A. Today's rule
    1. State Primacy Requirements for Implementation Flexibility
    2. State recordkeeping requirements
    3. State reporting requirements
    4. Interim primacy
    5. IDSE implementation
    B. Background and Analysis
    C. Summary of Major Comments
VI. Economic Analysis
    A. Regulatory Alternatives Considered
    B. Analyses that Support Today's Final Rule
    1. Predicting water quality and treatment changes
    2. Estimating benefits
    3. Estimating costs
    4. Comparing regulatory alternatives
    C. Benefits of the Stage 2 DBPR
    1. Nonquantified benefits
    2. Quantified benefits
    3. Timing of benefits accrual
    D. Costs of the Stage 2 DBPR
    1. Total annualized present value costs
    2. PWS costs
    a. IDSE costs
    b. PWS treatment costs
    c. Monitoring costs
    3. State/Primacy agency costs
    4. Non-quantified costs
    E. Household Costs of the Stage 2 DBPR
    F. Incremental Costs and Benefits of the Stage 2 DBPR
    G. Benefits From the Reduction of Co-occurring Contaminants
    H. Potential Risks From Other Contaminants
    1. Emerging DBPs
    2. N-nitrosamines
    3. Other DBPs
    I. Effects of the Contaminant on the General Population and 
Groups within the General Population that are Identified as Likely 
To Be at Greater Risk of Adverse Health Effects
    J. Uncertainties in the Risk, Benefit, and Cost Estimates for 
the Stage 2 DBPR
    K. Benefit/Cost Determination for the Stage 2 DBPR
    L. Summary of Major Comments
    1. Interpretation of health effects studies
    2. Derivation of benefits
    3. Use of SWAT
    5. Unanticipated risk issues
    6. Valuation of cancer cases avoided
VII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children from 
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions to Address 
Environmental Justice in Minority Populations or Low-Income 
Populations
    K. Consultations with the Science Advisory Board, National 
Drinking Water Advisory Council, and the Secretary of Health and 
Human Services
    L. Plain Language
    M. Analysis of the Likely Effect of Compliance With the Stage 2 
DBPR on the Technical, Managerial, and Financial Capacity of Public 
Water Systems
    N. Congressional Review Act
VIII. References

II. Summary of the Final Rule

A. Why is EPA Promulgating the Stage 2 DBPR?

    The Environmental Protection Agency is finalizing the Stage 2 
Disinfectants and Disinfection Byproduct Rule (DBPR) to reduce 
potential cancer risks and address concerns with potential reproductive 
and developmental risks from DBPs. The Agency is committed to ensuring 
that all public water systems provide clean and safe drinking water. 
Disinfectants are an essential element of drinking water treatment 
because of the barrier they provide against harmful waterborne 
microbial pathogens. However, disinfectants react with naturally 
occurring organic and inorganic matter in source water and distribution 
systems to form disinfection byproducts (DBPs) that may pose health 
risks. The Stage 2 DBPR is designed to reduce the level of exposure 
from DBPs without undermining the control of microbial pathogens. The 
Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) is being 
finalized and implemented simultaneously with the Stage 2 DBPR to 
ensure that drinking water is microbiologically safe at the limits set 
for DBPs.
    Congress required EPA to promulgate the Stage 2 DBPR as part of the 
1996 Safe Drinking Water Act (SDWA) Amendments (section 1412(b)(2)(C)). 
The Stage 2 DBPR augments the Stage 1 DBPR that was finalized in 1998 
(63 FR 69390, December 16, 1998) (USEPA

[[Page 391]]

1998a). The goal of the Stage 2 DBPR is to target the highest risk 
systems for changes beyond those required for Stage 1 DBPR. Today's 
rule reflects consensus recommendations from the Stage 2 Microbial/
Disinfection Byproducts (M-DBP) Federal Advisory Committee (the 
Advisory Committee) as well as public comments.
    New information on health effects, occurrence, and treatment has 
become available since the Stage 1 DBPR that supports the need for the 
Stage 2 DBPR. EPA has completed a more extensive analysis of health 
effects, particularly reproductive and developmental endpoints, 
associated with DBPs since the Stage 1 DBPR. Some recent studies on 
both human epidemiology and animal toxicology have shown possible 
associations between chlorinated drinking water and reproductive and 
developmental endpoints such as spontaneous abortion, stillbirth, 
neural tube and other birth defects, intrauterine growth retardation, 
and low birth weight. While results of these studies have been mixed, 
EPA believes they support a potential hazard concern. New epidemiology 
and toxicology studies evaluating bladder, colon, and rectal cancers 
have increased the weight of evidence linking these health effects to 
DBP exposure. The large number of people (more than 260 million 
Americans) exposed to DBPs and the potential cancer, reproductive, and 
developmental risks have played a significant role in EPA's decision to 
move forward with regulatory changes that target lowering DBP exposures 
beyond the requirements of the Stage 1 DBPR.
    While the Stage 1 DBPR is predicted to provide a major reduction in 
DBP exposure, national survey data suggest that some customers may 
receive drinking water with elevated, or peak, DBP concentrations even 
when their distribution system is in compliance with the Stage 1 DBPR. 
Some of these peak concentrations are substantially greater than the 
Stage 1 DBPR maximum contaminant levels (MCLs) and some customers 
receive these elevated levels of DBPs on a consistent basis. The new 
survey results also show that Stage 1 DBPR monitoring sites may not be 
representative of higher DBP concentrations that occur in distribution 
systems. In addition, new studies indicate that cost-effective 
technologies including ultraviolet light (UV) and granular activated 
carbon (GAC) may be very effective at lowering DBP levels. EPA's 
analysis of this new occurrence and treatment information indicates 
that significant public health benefits may be achieved through 
further, cost-effective reductions of DBPs in distribution systems.
    The Stage 2 DBPR presents a risk-targeting approach to reduce risks 
from DBPs. The new requirements provide for more consistent, equitable 
protection from DBPs across the entire distribution system and the 
reduction of DBP peaks. New risk-targeting provisions require systems 
to first identify their risk level; then, only those systems with the 
greatest risk will need to make operational or treatment changes. The 
Stage 2 DBPR, in conjunction with the LT2ESWTR, will help public water 
systems deliver safer water to Americans with the benefits of 
disinfection to control pathogens and with fewer risks from DBPs.

B. What Does the Stage 2 DBPR Require?

    The risk-targeting components of the Stage 2 DBPR focus the 
greatest amount of change where the greatest amount of risk may exist. 
Therefore, the provisions of the Stage 2 DBPR focus first on 
identifying the higher risks through the Initial Distribution System 
Evaluation (IDSE). The rule then addresses reducing exposure and 
lowering DBP peaks in distribution systems by using a new method to 
determine MCL compliance (locational running annual average (LRAA)), 
defining operational evaluation levels, and regulating consecutive 
systems. This section briefly describes the requirements of this final 
rule. More detailed information on the regulatory requirements for this 
rule can be found in Section IV.
1. Initial Distribution System Evaluation
    The first provision, designed to identify higher risk systems, is 
the Initial Distribution System Evaluation (IDSE). The purpose of the 
IDSE is to identify Stage 2 DBPR compliance monitoring sites that 
represent each system's highest levels of DBPs. Because Stage 2 DBPR 
compliance will be determined at these new monitoring sites, only those 
systems that identify elevated concentrations of TTHM and HAA5 will 
need to make treatment or process changes to bring the system into 
compliance with the Stage 2 DBPR. By identifying compliance monitoring 
sites with the highest concentrations of TTHM and HAA5 in each system's 
distribution system, the IDSE will offer increased assurance that MCLs 
are being met across the distribution system and that customers are 
receiving more equitable public health protection. Both treatment 
changes and awareness of TTHM and HAA5 levels resulting from the IDSE 
will allow systems to better control for distribution system peaks.
    The IDSE is designed to offer flexibility to public water systems. 
The IDSE requires TTHM and HAA5 monitoring for one year on a regular 
schedule that is determined by source water type and system size. 
Alternatively, systems have the option of performing a site-specific 
study based on historical data, water distribution system models, or 
other data; and waivers are available under certain circumstances. The 
IDSE requirements are discussed in Sections IV.E, IV.F., and IV.G of 
this preamble and in subpart U of the rule language.

2. Compliance and Monitoring Requirements

    As in Stage 1, the Stage 2 DBPR focuses on monitoring for and 
reducing concentrations of two classes of DBPs: total trihalomethanes 
(TTHM) and haloacetic acids (HAA5). These two groups of DBPs act as 
indicators for the various byproducts that are present in water 
disinfected with chlorine or chloramine. This means that concentrations 
of TTHM and HAA5 are monitored for compliance, but their presence in 
drinking water is representative of many other chlorination DBPs that 
may also occur in the water; thus, a reduction in TTHM and HAA5 
generally indicates an overall reduction of DBPs.
    The second provision of the Stage 2 DBPR is designed to address 
spatial variations in DBP exposure through a new compliance calculation 
(referred to as locational running annual average) for TTHM and HAA5 
MCLs. The MCL values remain the same as in the Stage 1. The Stage 1 
DBPR running annual average (RAA) calculation allowed some locations 
within a distribution system to have higher DBP annual averages than 
others as long as the system-wide average was below the MCL. The Stage 
2 DBPR bases compliance on a locational running annual average (LRAA) 
calculation, where the annual average at each sampling location in the 
distribution system will be used to determine compliance with the MCLs 
of 0.080 mg/L and 0.060 mg/L for TTHM and HAA5, respectively. The LRAA 
will reduce exposures to high DBP concentrations by ensuring that each 
monitoring site is in compliance with the MCLs as an annual average, 
while providing all customers drinking water that more consistently 
meets the MCLs. A more detailed discussion of Stage 2 DBPR MCL 
requirements can be found in Sections IV.C, IV.E, and IV.G of this 
preamble and in Sec.  141.64(b)(2) and (3) and subpart V of the rule 
language.
    The number of compliance monitoring sites is based on the

[[Page 392]]

population served and the source water type. EPA believes that 
population-based monitoring provides better risk-targeting and is 
easier to implement. Section IV.G describes population-based monitoring 
and how it affects systems complying with this rule.
    The Stage 2 DBPR includes new MCLGs for chloroform, 
monochloroacetic acid, and trichloroacetic acid, but these new MCLGs do 
not affect the MCLs for TTHM or HAA5.
3. Operational Evaluation Levels
    The IDSE and LRAA calculation will lead to lower DBP concentrations 
overall and reduce short term exposures to high DBP concentrations in 
certain areas, but this strengthened approach to regulating DBPs will 
still allow individual DBP samples above the MCL even when systems are 
in compliance with the Stage 2 DBPR. Today's rule requires systems that 
exceed operational evaluation levels (referred to as significant 
excursions in the proposed rule) to evaluate system operational 
practices and identify opportunities to reduce DBP concentrations in 
the distribution system. This provision will curtail peaks by providing 
systems with a proactive approach to remain in compliance. Operational 
evaluation requirements are discussed in greater detail in Section 
IV.H.
4. Consecutive Systems
    The Stage 2 DBPR also contains provisions for regulating 
consecutive systems, defined in the Stage 2 DBPR as public water 
systems that buy or otherwise receive some or all of their finished 
water from another public water system. Uniform regulation of 
consecutive systems provided by the Stage 2 DBPR will ensure that 
consecutive systems deliver drinking water that meets applicable DBP 
standards, thereby providing better, more equitable public health 
protection. More information on regulation of consecutive systems can 
be found in Sections IV.B, IV.E, and IV.G.

C. Correction of Sec.  141.132

    Section 553 of the Administrative Procedure Act, 5 U.S.C. 
553(b)(B), provides that, when an agency for good cause finds that 
notice and public procedure are impracticable, unnecessary, or contrary 
to the public interest, the agency may issue a rule without providing 
prior notice and an opportunity for public comment. In addition to 
promulgating the Stage 2 regulations, this rule also makes a minor 
correction to the National Primary Drinking Water Regulations, 
specifically the Stage 1 Disinfection Byproducts Rule. This rule 
corrects a technical error made in the January 16, 2001, Federal 
Register Notice (66 FR 3769) (see page 3770). This rule restores the 
following sentence that was inadvertently removed from Sec.  141.132 
(b)(1)(iii), ``Systems on a reduced monitoring schedule may remain on 
that reduced schedule as long as the average of all samples taken in 
the year (for systems which must monitor quarterly) or the result of 
the sample (for systems which must monitor no more frequently than 
annually) is no more than 0.060 mg/L and 0.045 mg/L for TTHMs and HAA5, 
respectively.'' This text had been part of the original regulation when 
it was codified in the CFR on December 16, 1998. However, as a result 
of a subsequent amendment to that regulatory text, the text discussed 
today was removed. EPA recognized the error only after publication of 
the new amendment, and is now correcting the error. EPA is merely 
restoring to the CFR language that EPA had promulgated on December 16, 
1998. EPA is not creating any new rights or obligations by this 
technical correction. Thus, additional notice and public comment is not 
necessary. EPA finds that this constitutes ``good cause'' under 5 
U.S.C. 553(b)(B).

III. Background

    A combination of factors influenced the development of the Stage 2 
DBPR. These include the initial 1992-1994 Microbial and Disinfection 
Byproduct (M-DBP) stakeholder deliberations and EPA's Stage 1 DBPR 
proposal (USEPA 1994); the 1996 Safe Drinking Water Act (SDWA) 
Amendments; the 1996 Information Collection Rule; the 1998 Stage 1 
DBPR; new data, research, and analysis on disinfection byproduct (DBP) 
occurrence, treatment, and health effects since the Stage 1 DBPR; and 
the Stage 2 DBPR Microbial and Disinfection Byproducts Federal Advisory 
Committee. The following sections provide summary background 
information on these subjects. For additional information, see the 
proposed Stage 2 DBPR and supporting technical material where cited (68 
FR 49548, August 18, 2003) (USEPA 2003a).

A. Statutory Requirements and Legal Authority

    The SDWA, as amended in 1996, authorizes EPA to promulgate a 
national primary drinking water regulation (NPDWR) and publish a 
maximum contaminant level goal (MCLG) for any contaminant the 
Administrator determines ``may have an adverse effect on the health of 
persons,'' is ``known to occur or there is a substantial likelihood 
that the contaminant will occur in public water systems with a 
frequency and at levels of public health concern,'' and for which ``in 
the sole judgement of the Administrator, regulation of such contaminant 
presents a meaningful opportunity for health risk reduction for persons 
served by public water systems'' (SDWA section 1412(b)(1)(A)). MCLGs 
are non-enforceable health goals set at a level at which ``no known or 
anticipated adverse effects on the health of persons occur and which 
allows an adequate margin of safety.'' These health goals are published 
at the same time as the NPDWR (SDWA sections 1412(b)(4) and 
1412(a)(3)).
    SDWA also requires each NPDWR for which an MCLG is established to 
specify an MCL that is as close to the MCLG as is feasible (sections 
1412(b)(4) and 1401(1)(C)). The Agency may also consider additional 
health risks from other contaminants and establish an MCL ``at a level 
other than the feasible level, if the technology, treatment techniques, 
and other means used to determine the feasible level would result in an 
increase in the health risk from drinking water by--(i) increasing the 
concentration of other contaminants in drinking water; or (ii) 
interfering with the efficacy of drinking water treatment techniques or 
processes that are used to comply with other national primary drinking 
water regulations'' (section 1412(b)(5)(A)). When establishing an MCL 
or treatment technique under this authority, ``the level or levels or 
treatment techniques shall minimize the overall risk of adverse health 
effects by balancing the risk from the contaminant and the risk from 
other contaminants the concentrations of which may be affected by the 
use of a treatment technique or process that would be employed to 
attain the maximum contaminant level or levels'' (section 
1412(b)(5)(B)). In today's rule, the Agency is establishing MCLGs and 
MCLs for certain DBPs, as described in Section IV.
    Finally, section 1412(b)(2)(C) of the Act requires EPA to 
promulgate a Stage 2 DBPR. Consistent with statutory provisions for 
risk balancing (section 1412(b)(5)(B)), EPA is finalizing the LT2ESWTR 
concurrently with the Stage 2 DBPR to ensure simultaneous protection 
from microbial and DBP risks.

B. What is the Regulatory History of the Stage 2 DBPR and How Were 
Stakeholders Involved?

    This section first summarizes the existing regulations aimed at 
controlling

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levels of DBPs in drinking water. The Stage 2 DBPR establishes 
regulatory requirements beyond these rules that target high risk 
systems and provide for more equitable protection from DBPs across the 
entire distribution system. Next, this section summarizes the extensive 
stakeholder involvement in the development of the Stage 2 DBPR.
1. Total Trihalomethanes Rule
    The first rule to regulate DBPs was promulgated on November 29, 
1979. The Total Trihalomethanes Rule (44 FR 68624, November 29, 1979) 
(USEPA 1979) set an MCL of 0.10 mg/L for total trihalomethanes (TTHM). 
Compliance was based on the running annual average (RAA) of quarterly 
averages of all samples collected throughout the distribution system. 
This TTHM standard applied only to community water systems using 
surface water and/or ground water that served at least 10,000 people 
and added a disinfectant to the drinking water during any part of the 
treatment process.
2. Stage 1 Disinfectants and Disinfection Byproducts Rule
    The Stage 1 DBPR, finalized in 1998 (USEPA 1998a), applies to all 
community and nontransient noncommunity water systems that add a 
chemical disinfectant to water. The rule established maximum residual 
disinfectant level goals (MRDLGs) and enforceable maximum residual 
disinfectant level (MRDL) standards for three chemical disinfectants--
chlorine, chloramine, and chlorine dioxide; maximum contaminant level 
goals (MCLGs) for three trihalomethanes (THMs), two haloacetic acids 
(HAAs), bromate, and chlorite; and enforceable maximum contaminant 
level (MCL) standards for TTHM, five haloacetic acids (HAA5), bromate 
(calculated as running annual averages (RAAs)), and chlorite (based on 
daily and monthly sampling). The Stage 1 DBPR uses TTHM and HAA5 as 
indicators of the various DBPs that are present in disinfected water. 
Under the Stage 1 DBPR, water systems that use surface water or ground 
water under the direct influence of surface water and use conventional 
filtration treatment are required to remove specified percentages of 
organic materials, measured as total organic carbon (TOC), that may 
react with disinfectants to form DBPs. Removal is achieved through 
enhanced coagulation or enhanced softening, unless a system meets one 
or more alternative compliance criteria.
    The Stage 1 DBPR was one of the first rules to be promulgated under 
the 1996 SDWA Amendments (USEPA 1998a). EPA finalized the Interim 
Enhanced Surface Water Treatment Rule (63 FR 69477, December 16, 1998) 
(USEPA 1998b) at the same time as the Stage 1 DBPR to ensure 
simultaneous compliance and address risk tradeoff issues. Both rules 
were products of extensive Federal Advisory Committee deliberations and 
final consensus recommendations in 1997.
3. Stakeholder Involvement
    a. Federal Advisory Committee process. EPA reconvened the M-DBP 
Advisory Committee in March 1999 to develop recommendations on issues 
pertaining to the Stage 2 DBPR and LT2ESWTR. The Stage 2 M-DBP Advisory 
Committee consisted of 21 organizational members representing EPA, 
State and local public health and regulatory agencies, local elected 
officials, Native American Tribes, large and small drinking water 
suppliers, chemical and equipment manufacturers, environmental groups, 
and other stakeholders. Technical support for the Advisory Committee's 
discussions was provided by a technical working group established by 
the Advisory Committee. The Advisory Committee held ten meetings from 
September 1999 to July 2000, which were open to the public, with an 
opportunity for public comment at each meeting.
    The Advisory Committee carefully considered extensive new data on 
the occurrence and health effects of DBPs, as well as costs and 
potential impacts on public water systems. In addition, they considered 
risk tradeoffs associated with treatment changes. Based upon this 
detailed technical evaluation, the committee concluded that a targeted 
protective public health approach should be taken to address exposure 
to DBPs beyond the requirements of the Stage 1 DBPR. While there had 
been substantial research to date, the Advisory Committee also 
concluded that significant uncertainty remained regarding the risk 
associated with DBPs in drinking water. After reaching these 
conclusions, the Advisory Committee developed an Agreement in Principle 
(65 FR 83015, December 29, 2000) (USEPA 2000a) that laid out their 
consensus recommendations on how to further control DBPs in public 
water systems, which are reflected in today's final rule.
    In the Agreement in Principle, the Advisory Committee recommended 
maintaining the MCLs for TTHM and HAA5 at 0.080 mg/L and 0.060 mg/L, 
respectively, but changing the compliance calculation in two phases to 
facilitate systems moving from the running annual average (RAA) 
calculation to a locational running annual average (LRAA) calculation. 
In the first phase, systems would continue to comply with the Stage 1 
DBPR MCLs as RAAs and, at the same time, comply with MCLs of 0.120 mg/L 
for TTHM and 0.100 mg/L for HAA5 calculated as LRAAs. RAA calculations 
average all samples collected within a distribution system over a one-
year period, but LRAA calculations average all samples taken at each 
individual sampling location in a distribution system during a one-year 
period. Systems would also carry out an Initial Distribution System 
Evaluation (IDSE) to select compliance monitoring sites that reflect 
higher TTHM and HAA5 levels occurring in the distribution system. The 
second phase of compliance would require MCLs of 0.080 mg/L for TTHM 
and 0.060 mg/L for HAA5, calculated as LRAAs at individual monitoring 
sites identified through the IDSE. The first phase has been dropped in 
the final rule, as discussed in section IV.C.
    The Agreement in Principle also provided recommendations for 
simultaneous compliance with the LT2ESWTR so that the reduction of DBPs 
does not compromise microbial protection. The complete text of the 
Agreement in Principle (USEPA 2000a) can be found online at 
www.regulations.gov.
    b. Other outreach processes. EPA worked with stakeholders to 
develop the Stage 2 DBPR through various outreach activities other than 
the M-DBP Federal Advisory Committee process. The Agency consulted with 
State, local, and Tribal governments; the National Drinking Water 
Advisory Committee (NDWAC); the Science Advisory Board (SAB); and Small 
Entity Representatives (SERs) and small system operators (as part of an 
Agency outreach initiative under the Regulatory Flexibility Act). 
Section VII includes a complete description of the many stakeholder 
activities which contributed to the development of the Stage 2 DBPR.
    Additionally, EPA posted a pre-proposal draft of the Stage 2 DBPR 
preamble and regulatory language on an EPA Internet site on October 17, 
2001. This public review period allowed readers to comment on the Stage 
2 DBPR's consistency with the Agreement in Principle of the Stage 2 M-
DBP Advisory Committee. EPA received important suggestions on this pre-
proposal draft from 14 commenters, which included public water systems, 
State governments, laboratories, and other stakeholders.

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C. Public Health Concerns to be Addressed

    EPA is promulgating the Stage 2 rule to reduce the potential risks 
of cancer and reproductive and developmental health effects from DBPs. 
In addition, the provisions of the Stage 2 DBPR provide for more 
equitable public health protection. Sections C and D describe the 
general basis for this public health concern through reviewing 
information in the following areas: the health effects associated with 
DBPs, DBP occurrence, and the control of DBPs.
1. What Are DBPs?
    Chlorine has been widely used to kill disease-causing microbes in 
drinking water. The addition of chlorine in PWSs across the U.S. to 
kill microbial pathogens in the water supply has been cited as one of 
the greatest public health advances of the twentieth century (Okun 
2003). For example, during the decade 1880-1890, American cities 
experienced an average mortality rate of 58 per 100,000 from typhoid, 
which was commonly transmitted through contaminated water. By 1938, 
this rate had fallen to 0.67 deaths per 100,000, largely due to 
improved treatment of drinking water (Blake 1956).
    During the disinfection process, organic and inorganic material in 
source waters can combine with chlorine and certain other chemical 
disinfectants to form DBPs. More than 260 million people in the U.S. 
are exposed to disinfected water and DBPs (USEPA 2005a). Although 
chlorine is the most commonly applied disinfectant, other 
disinfectants, including ozone, chlorine dioxide, chloramine, and 
ultraviolet radiation, are in use. In combination with these, all 
surface water systems must also use either chlorine or chloramine to 
maintain a disinfectant residual in their distribution system. The kind 
of disinfectant used can produce different types and levels of 
disinfectant byproducts in the drinking water.
    Many factors affect the amount and kinds of DBPs in drinking water. 
Areas in the distribution system that have had longer contact time with 
chemical disinfectants tend to have higher levels of DBPs, such as 
sites farther from the treatment plant, dead ends in the system, and 
small diameter pipes. The makeup and source of the water also affect 
DBP formation. Different types of organic and inorganic material will 
form different types and levels of DBPs. Other factors, such as water 
temperature, season, pH, and location within the water purification 
process where disinfectants are added, can affect DBP formation within 
and between water systems.
    THMs and HAAs are widely occurring classes of DBPs formed during 
disinfection with chlorine and chloramine. The four THMs (TTHM) and 
five HAAs (HAA5) measured and regulated in the Stage 2 DBPR act as 
indicators for DBP occurrence. There are other known DBPs in addition 
to a variety of unidentified DBPs present in disinfected water. THMs 
and HAAs typically occur at higher levels than other known and 
unidentified DBPs (McGuire et al. 2002; Weinberg et al. 2002). The 
presence of TTHM and HAA5 is representative of the occurrence of many 
other chlorination DBPs; thus, a reduction in the TTHM and HAA5 
generally indicates an overall reduction of DBPs.
2. DBP Health Effects
    Since the mid 1980's, epidemiological studies have supported a 
potential association between bladder cancer and chlorinated water and 
possibly also with colon and rectal cancers. In addition, more recent 
health studies have reported potential associations between chlorinated 
drinking water and reproductive and developmental health effects.
    Based on a collective evaluation of both the human epidemiology and 
animal toxicology data on cancer and reproductive and developmental 
health effects discussed below and in consideration of the large number 
of people exposed to chlorinated byproducts in drinking water (more 
than 260 million), EPA concludes that (1) new cancer data since Stage 1 
strengthen the evidence of a potential association of chlorinated water 
with bladder cancer and suggests an association for colon and rectal 
cancers, (2) current reproductive and developmental health effects data 
do not support a conclusion at this time as to whether exposure to 
chlorinated drinking water or disinfection byproducts causes adverse 
developmental or reproductive health effects, but do support a 
potential health concern, and (3) the combined health data indicate a 
need for public health protection beyond that provided by the Stage 1 
DBPR.
    This section summarizes the key information in the areas of cancer, 
reproductive, and developmental health studies that EPA used to arrive 
at these conclusions. Throughout this writeup, EPA uses `weight of 
evidence,' `causality,' and `hazard' as follows:
     A `weight of evidence' evaluation is a collective 
evaluation of all pertinent information. Judgement about the weight of 
evidence involves considerations of the quality and adequacy of data 
and consistency of responses. These factors are not scored mechanically 
by adding pluses and minuses; they are judged in combination.
     Criteria for determining `causality' include consistency, 
strength, and specificity of association, a temporal relationship, a 
biological gradient (dose-response relationship), biological 
plausibility, coherence with multiple lines of evidence, evidence from 
human populations, and information on agent's structural analogues 
(USEPA 2005i). Additional considerations for individual study findings 
include reliable exposure data, statistical power and significance, and 
freedom from bias and confounding.
     The term `hazard' describes not a definitive conclusion, 
but the possibility that a health effect may be attributed to a certain 
exposure, in this case chlorinated water. Analyses done for the Stage 2 
DBPR follow the 1999 EPA Proposed Guidelines for Carcinogenic Risk 
Assessment (USEPA 1999a). In March 2005, EPA updated and finalized the 
Cancer Guidelines and a Supplementary Children's Guidance, which 
include new considerations on mode of action for cancer risk 
determination and additional potential risks due to early childhood 
exposure (USEPA 2005i; USEPA 2005j). Conducting the cancer evaluation 
using the 2005 Cancer Guidelines would not result in any change from 
the existing analysis. With the exception of chloroform, no mode of 
action has been established for other specific regulated DBPs. Although 
some of the DBPs have given mixed mutagenicity and genotoxicity 
results, having a positive mutagenicity study does not necessarily mean 
that a chemical has a mutagenic mode of action. The extra factor of 
safety for children's health protection does not apply because the new 
Supplementary Children's Guidance requires application of the 
children's factor only when a mutagenic mode of action has been 
identified.
    a. Cancer health effects. The following section briefly discusses 
cancer epidemiology and toxicology information EPA analyzed and some 
conclusions of these studies and reports. Further discussion of these 
studies and EPA's conclusions can be found in the proposed Stage 2 DBPR 
(USEPA 2003a) and the Economic Analysis for the Final Stage 2 
Disinfectants and Disinfection Byproducts Rule (Economic Analysis (EA)) 
(USEPA 2005a).
    Human epidemiology studies and animal toxicology studies have

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examined associations between chlorinated drinking water or DBPs and 
cancer. While EPA cannot conclude there is a causal link between 
exposure to chlorinated surface water and cancer, EPA believes that the 
available research indicates a potential association between bladder 
cancer and exposure to chlorinated drinking water or DBPs. EPA also 
believes the available research suggests a possible association between 
rectal and colon cancers and exposure to chlorinated drinking water or 
DBPs. This is based on EPA's evaluation of all available cancer 
studies. The next two sections focus on studies published since the 
Stage 1 DBPR. Conclusions are based on the research as a whole.
    i. Epidemiology. A number of epidemiological studies have been 
conducted to investigate the relationship between exposure to 
chlorinated drinking water and various cancers. These studies 
contribute to the overall evidence on potential human health hazards 
from exposure to chlorinated drinking water.
    Epidemiology studies provide useful health effects information 
because they reflect human exposure to a drinking water DBP mixture 
through multiple routes of intake such as ingestion, inhalation and 
dermal absorption. The greatest difficulty with conducting cancer 
epidemiology studies is the length of time between exposure and effect. 
Higher quality studies have adequately controlled for confounding and 
have limited the potential for exposure misclassification, for example, 
using DBP levels in drinking water as the exposure metric as opposed to 
type of source water. Study design considerations for interpreting 
cancer epidemiology data include sufficient follow-up time to detect 
disease occurrence, adequate sample size, valid ascertainment of cause 
of the cancer, and reduction of potential selection bias in case-
control and cohort studies (by having comparable cases and controls and 
by limiting loss to follow-up). Epidemiology studies provide extremely 
useful information on human exposure to chlorinated water, which 
complement single chemical, high dose animal data.
    In the Stage 1 DBPR, EPA concluded that the epidemiological 
evidence suggested a potential increased risk for bladder cancer. Some 
key studies EPA considered for Stage 1 include Cantor et al. (1998), 
Doyle et al. (1997), Freedman et al. (1997), King and Marrett (1996), 
McGeehin et al. (1993), Cantor et al. (1987), and Cantor et al. (1985). 
Several studies published since the Stage 1 DBPR continue to support an 
association between increased risk of bladder cancer and exposure to 
chlorinated surface water (Chevrier et al. 2004; Koivusalo et al. 1998; 
Yang et al. 1998). One study found no effects on a biomarker of 
genotoxicity in urinary bladder cells from TTHM exposure (Ranmuthugala 
et al. 2003). Epidemiological reviews and meta-analyses generally 
support the possibility of an association between chlorinated water or 
THMs and bladder cancer (Villanueva et al. 2004; Villanueva et al. 
2003; Villanueva et al. 2001; Mills et al. 1998). The World Health 
Organization (WHO 2000) found data inconclusive or insufficient to 
determine causality between chlorinated water and any health endpoint, 
although they concluded that the evidence is better for bladder cancer 
than for other cancers.
    In the Stage 1 DBPR, EPA concluded that early studies suggested a 
small possible increase in rectal and colon cancers from exposure to 
chlorinated surface waters. The database of studies on colon and rectal 
cancers continues to support a possible association, but evidence 
remains mixed. For colon cancer, one newer study supports the evidence 
of an association (King et al. 2000a) while others showed inconsistent 
findings (Hildesheim et al. 1998; Yang et al. 1998). Rectal cancer 
studies are also mixed. Hildesheim et al. (1998) and Yang et al. (1998) 
support an association with rectal cancer while King et al. (2000a) did 
not. A review of colon and rectal cancer concluded evidence was 
inconclusive but that there was a stronger association for rectal 
cancer and chlorination DBPs than for colon cancer (Mills et al. 1998). 
The WHO (2000) review reported that studies showed weak to moderate 
associations with colon and rectal cancers and chlorinated surface 
water or THMs but that evidence is inadequate to evaluate these 
associations.
    Recent studies on kidney, brain, and lung cancers and DBP exposure 
support a possible association (kidney: Yang et al. 1998, Koivusalo et 
al. 1998; brain: Cantor et al. 1999; lung: Yang et al. 1998). However, 
so few studies have examined these endpoints that definitive 
conclusions cannot be made. Studies on leukemia found little or no 
association with DBPs (Infante-Rivard et al. 2002; Infante-Rivard et 
al. 2001). A recent study did not find an association between 
pancreatic cancer and DBPs (Do et al. 2005). A study researching 
multiple cancer endpoints found an association between THM exposure and 
all cancers when grouped together (Vinceti et al. 2004). More details 
on the cancer epidemiology studies since the Stage 1 DBPR are outlined 
in Table II.D-1.

                 Table II.D-1.--Summary of Cancer Epidemiology Studies Reviewed for Stage 2 DBPR
----------------------------------------------------------------------------------------------------------------
                                                       Exposure(s)         Outcome(s)
                                     Study type          studied            measured             Findings
----------------------------------------------------------------------------------------------------------------
           Author(s)
Do et al. 2005.................  Case-control       Estimated          Pancreatic cancer  No association was
                                  study in Canada,   chlorinated                           found between
                                  1994-1997.         DBPs,                                 pancreatic cancer and
                                                     chloroform, BDCM                      exposure to
                                                     concentrations.                       chlorinated DBPs,
                                                                                           chloroform, or BDCM.
Chevrier et al. 2004...........  Case-control       Compared THM       Bladder cancer...  A statistically
                                  study in France,   levels, duration                      significant decreased
                                  1985-1987.         of exposure, and                      risk of bladder
                                                     3 types of water                      cancer was found as
                                                     treatment                             duration of exposure
                                                     (ozonation,                           to ozonated water
                                                     chlorination,                         increased. This was
                                                     ozonation/                            evident with and
                                                     chlorination).                        without adjustment
                                                                                           for other exposure
                                                                                           measures. A small
                                                                                           association was
                                                                                           detected for
                                                                                           increased bladder
                                                                                           cancer risk and
                                                                                           duration of exposure
                                                                                           to chlorinated
                                                                                           surface water and
                                                                                           with the estimated
                                                                                           THM content of the
                                                                                           water, achieving
                                                                                           statistical
                                                                                           significance only
                                                                                           when adjusted for
                                                                                           duration of ozonated
                                                                                           water exposures.
                                                                                           Effect modification
                                                                                           by gender was noted
                                                                                           in the adjusted
                                                                                           analyses.

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Vinceti et al. 2004............  Retrospective      Standardized       15 cancers         Mortality ratio from
                                  cohort study in    mortality ratios   including colon,   all cancers showed a
                                  Italy, 1987-1999.  from all causes    rectum, and        statistically
                                                     vs. cancer for     bladder.           significant small
                                                     consumers                             increase for males
                                                     drinking water                        consuming drinking
                                                     with high THMs.                       water with high THMs.
                                                                                           For females, an
                                                                                           increased mortality
                                                                                           ratio for all cancers
                                                                                           was seen but was not
                                                                                           statistically
                                                                                           significant. Stomach
                                                                                           cancer in men was the
                                                                                           only individual
                                                                                           cancer in which a
                                                                                           statistically
                                                                                           significant excess in
                                                                                           mortality was
                                                                                           detected for
                                                                                           consumption of
                                                                                           drinking water with
                                                                                           high THMs.
Ranmuthugala et al. 2003.......  Cohort study in 3  Estimated dose of  Frequency of       Relative risk
                                  Australian         TTHM,              micronuclei in     estimates for DNA
                                  communities,       chloroform, and    urinary bladder    damage to bladder
                                  1997.              bromoform from     epithelial cells.  cells for THM dose
                                                     routinely-                            metrics were near
                                                     collected THM                         1.0. The study
                                                     measurements and                      provides no evidence
                                                     fluid intake                          that THMs are
                                                     diary.                                associated with DNA
                                                                                           damage to bladder
                                                                                           epithelial cells, and
                                                                                           dose-response
                                                                                           patterns were not
                                                                                           detected.
Infante-Rivard et al. 2002.....  Population-based   Estimated          Acute              Data are suggestive,
                                  case-control       prenatal and       lymphoblastic      but imprecise,
                                  study in Quebec,   postnatal          leukemia.          linking DNA variants
                                  1980-1993.         exposure to THMs                      with risk of acute
                                                     and                                   lymphoblastic
                                                     polymorphisms in                      leukemia associated
                                                     two genes.                            with drinking water
                                                                                           DBPs. The number of
                                                                                           genotyped subjects
                                                                                           for GSTT1 and CYP2E1
                                                                                           genes was too small
                                                                                           to be conclusive.
Infante-Rivard et al. 2001.....  Population-based   Compared water     Acute              No increased risk for
                                  case-control       chlorination       lymphoblastic      lymphoblastic
                                  study in Quebec,   (never,            leukemia.          leukemia was observed
                                  1980-1993.         sometimes,                            for prenatal exposure
                                                     always) and                           at average levels of
                                                     exposure to                           TTHMs, metals or
                                                     TTHMs, metals,                        nitrates. However, a
                                                     and nitrates.                         non-statistically
                                                                                           significant, small
                                                                                           increased risk was
                                                                                           seen for postnatal
                                                                                           cumulative exposure
                                                                                           to TTHMs and
                                                                                           chloroform (both at
                                                                                           above the 95th
                                                                                           exposure percentile
                                                                                           of the distribution
                                                                                           for cases and
                                                                                           controls), for zinc,
                                                                                           cadmium, and arsenic,
                                                                                           but not other metals
                                                                                           or nitrates.
King et al. 2000a..............  Population-based   Compared source    Colon and rectal   Colon cancer risk was
                                  case-control       of drinking        cancer.            statistically
                                  study in           water and                             associated with
                                  southern           chlorination                          cumulative long term
                                  Ontario, 1992-     status.                               exposure to THMs,
                                  1994.              Estimated TTHM                        chlorinated surface
                                                     levels, duration                      water, and tap water
                                                     of exposure, and                      consumption metrics
                                                     tap water                             among males only.
                                                     consumption.                          Exposure-response
                                                                                           relationships were
                                                                                           evident for exposure
                                                                                           measures combining
                                                                                           duration and THM
                                                                                           levels. Associations
                                                                                           between the exposure
                                                                                           measures and rectal
                                                                                           cancer were not
                                                                                           observed for either
                                                                                           gender.
Cantor et al. 1999.............  Population-based   Compared level     Brain cancer.....  Among males, a
                                  case-control       and duration of                       statistically
                                  study in Iowa,     THM exposure                          significant increased
                                  1984-1987.         (cumulative and                       risk of brain cancer
                                                     average), source                      was detected for
                                                     of water,                             duration of
                                                     chlorination,                         chlorinated versus
                                                     and water                             non-chlorinated
                                                     consumption.                          source water,
                                                                                           especially among high-
                                                                                           level consumers of
                                                                                           tap water. An
                                                                                           increased risk of
                                                                                           brain cancer for high
                                                                                           water intake level
                                                                                           was found in men. No
                                                                                           associations were
                                                                                           found for women for
                                                                                           any of the exposure
                                                                                           metrics examined.
Cantor et al. 1998.............  Population-based   Compared level     Bladder cancer...  A statistically
                                  case-control       and duration of                       significant positive
                                  study in Iowa,     THM exposure                          association between
                                  1986-1989.         (cumulative and                       risk of bladder
                                                     average), source                      cancer and exposure
                                                     of water,                             to chlorinated
                                                     chlorination,                         groundwater or
                                                     and water                             surface water
                                                     consumption.                          reported for men and
                                                                                           for smokers, but no
                                                                                           association found for
                                                                                           male/female non-
                                                                                           smokers, or for women
                                                                                           overall. Limited
                                                                                           evidence was found
                                                                                           for an association
                                                                                           between tapwater
                                                                                           consumption and
                                                                                           bladder cancer risk.
                                                                                           Suggestive evidence
                                                                                           existed for exposure-
                                                                                           response effects of
                                                                                           chlorinated water and
                                                                                           lifetime THM measures
                                                                                           on bladder cancer
                                                                                           risk.
Hildesheim et al. 1998.........  Population-based   Compared level     Colon and rectal   Increased risks of
                                  case-control       and duration of    cancer.            rectal cancer was
                                  study in Iowa,     THM exposure                          associated with
                                  1986-1989.         (cumulative and                       duration of exposure
                                                     average), source                      to chlorinated
                                                     of water,                             surface water and any
                                                     chlorination,                         chlorinated water,
                                                     and water                             with evidence of an
                                                     consumption.                          exposure-response
                                                                                           relationship. Risk of
                                                                                           rectal cancer is
                                                                                           statistically
                                                                                           significant increased
                                                                                           with >60 years
                                                                                           lifetime exposure to
                                                                                           THMs in drinking
                                                                                           water, and risk
                                                                                           increased for
                                                                                           individuals with low
                                                                                           dietary fiber intake.
                                                                                           Risks were similar
                                                                                           for men and women and
                                                                                           no effects were
                                                                                           observed for tapwater
                                                                                           measures. No
                                                                                           associations were
                                                                                           detected for water
                                                                                           exposure measures and
                                                                                           risk of colon cancer.
Koivusalo et al. 1998..........  Population-based   Estimated          Bladder and        Drinking water
                                  case-control       residential        kidney cancer.     mutagenicity was
                                  study in           duration of                           associated with a
                                  Finland, 1991-     exposure and                          small, statistically
                                  1992.              level of                              significant, exposure-
                                                     drinking water                        related excess risk
                                                     mutagenicity.                         for kidney and
                                                                                           bladder cancers among
                                                                                           men; weaker
                                                                                           associations were
                                                                                           detected for
                                                                                           mutagenic water and
                                                                                           bladder or kidney
                                                                                           cancer among women.
                                                                                           The effect of
                                                                                           mutagenicity on
                                                                                           bladder cancer was
                                                                                           modified by smoking
                                                                                           status, with an
                                                                                           increased risk among
                                                                                           non-smokers.

[[Page 397]]

 
Yang et al. 1998...............  Cross-sectional    Examined           Cancer of rectum,  Residence in
                                  study in Taiwan,   residence in       lung, bladder,     chlorinating
                                  1982-1991.         chlorinated        kidney, colon,     municipalities (vs.
                                                     (mainly surface    and 11 others.     non-chlorinating) was
                                                     water sources)                        statistically
                                                     relative to non-                      significantly
                                                     chlorinated                           associated with the
                                                     (mainly private                       following types of
                                                     well) water.                          cancer in both males
                                                                                           and females: rectal,
                                                                                           lung, bladder, and
                                                                                           kidney cancer. Liver
                                                                                           cancer and all
                                                                                           cancers were also
                                                                                           statistically
                                                                                           significantly
                                                                                           elevated in
                                                                                           chlorinated towns for
                                                                                           males only. Mortality
                                                                                           rates for cancers of
                                                                                           the esophagus,
                                                                                           stomach, colon,
                                                                                           pancreas, prostate,
                                                                                           brain, breast, cervix
                                                                                           uteri and uterus, and
                                                                                           ovary were comparable
                                                                                           for chlorinated and
                                                                                           non-chlorinated
                                                                                           residence.
Doyle et al. 1997..............  Prospective        Examined           Colon, rectum,     Statistically
                                  cohort study in    chloroform         bladder, and 8     significant increased
                                  Iowa, 1987-1993.   levels and         other cancers in   risk of colon cancer,
                                                     source of          women.             breast cancer and all
                                                     drinking water.                       cancers combined was
                                                                                           observed for women
                                                                                           exposed to chloroform
                                                                                           in drinking water,
                                                                                           with evidence of
                                                                                           exposure-response
                                                                                           effects. No
                                                                                           associations were
                                                                                           detected between
                                                                                           chloroform and
                                                                                           bladder, rectum,
                                                                                           kidney, upper
                                                                                           digestive organs,
                                                                                           lung, ovary,
                                                                                           endometrium, or
                                                                                           breast cancers, or
                                                                                           for melanomas or non-
                                                                                           Hodgkin's lymphoma.
                                                                                           Surface water
                                                                                           exposure (compared to
                                                                                           ground water users)
                                                                                           was also a
                                                                                           significant predictor
                                                                                           of colon and breast
                                                                                           cancer risk.
Freedman et al. 1997...........  Population-based   Estimated          Bladder cancer...  There was a weak
                                  case-control       duration of                           association between
                                  study in           exposure to                           bladder cancer risk
                                  Maryland, 1975-    chlorinated                           and duration of
                                  1992.              water. Compared                       exposure to municipal
                                                     exposure to                           water for male
                                                     chlorinated                           cigarette smokers, as
                                                     municipal water                       well as an exposure-
                                                     (yes/no).                             response
                                                                                           relationship. No
                                                                                           association was seen
                                                                                           for those with no
                                                                                           history of smoking,
                                                                                           suggesting that
                                                                                           smoking may modify a
                                                                                           possible effect of
                                                                                           chlorinated surface
                                                                                           water on the risk of
                                                                                           bladder cancer.
King and Marrett 1996..........  Case-control       Compared source    Bladder cancer...  Statistically
                                  study in           of drinking                           significant
                                  Ontario, Canada,   water and                             associations were
                                  1992-1994.         chlorination                          detected for bladder
                                                     status.                               cancer and
                                                     Estimated TTHM                        chlorinated surface
                                                     levels, duration                      water, duration or
                                                     of exposure, and                      concentration of THM
                                                     tap water                             levels and tap water
                                                     consumption.                          consumption metrics.
                                                                                           Population
                                                                                           attributable risks
                                                                                           were estimated at 14
                                                                                           to 16 percent. An
                                                                                           exposure-response
                                                                                           relationship was
                                                                                           observed for
                                                                                           estimated duration of
                                                                                           high THM exposures
                                                                                           and risk of bladder
                                                                                           cancer.
McGeehin et al. 1993...........  Population-based   Compared source    Bladder cancer...  Statistically
                                  case-control       of drinking                           significant
                                  study in           water, water                          associations were
                                  Colorado, 1990-    treatment, and                        detected for bladder
                                  1991.              tap water versus                      cancer and duration
                                                     bottled water.                        of exposure to
                                                     Estimated                             chlorinated surface
                                                     duration of                           water. The risk was
                                                     exposure to                           similar for males and
                                                     TTHMs and levels                      females and among
                                                     of TTHMs,                             nonsmokers and
                                                     nitrates, and                         smokers. The
                                                     residual                              attributable risk was
                                                     chlorine.                             estimated at 14.9
                                                                                           percent. High tap
                                                                                           water intake was
                                                                                           associated with risk
                                                                                           of bladder cancer in
                                                                                           a exposure-response
                                                                                           fashion. No
                                                                                           associations were
                                                                                           detected between
                                                                                           bladder cancer and
                                                                                           levels of TTHMs,
                                                                                           nitrates, and
                                                                                           residual chlorine.
Cantor et al. 1987 (and Cantor   Population-based   Compared source    Bladder cancer...  Bladder cancer was
 et al. 1985).                    case-control       of drinking                           statistically
                                  study in 10        water. Estimated                      associated with
                                  areas of the       total beverage                        duration of exposure
                                  U.S., 1977-1978.   and tap water                         to chlorinated
                                                     consumption and                       surface water for
                                                     duration of                           women and nonsmokers
                                                     exposure.                             of both sexes. The
                                                                                           largest risks were
                                                                                           seen when both
                                                                                           exposure duration and
                                                                                           level of tap water
                                                                                           ingestion were
                                                                                           combined. No
                                                                                           association was seen
                                                                                           for total beverage
                                                                                           consumption.
     Reviews/Meta-analyses
Villanueva et al. 2004.........  Review and meta-   Individual-based   Bladder cancer...  The meta-analysis
                                  analysis of 6      exposure                              suggests that risk of
                                  case-control       estimates to                          bladder cancer in men
                                  studies.           THMs and water                        increases with long-
                                                     consumption over                      term exposure to
                                                     a 40-year period.                     TTHMs. An exposure-
                                                                                           response pattern was
                                                                                           observed among men
                                                                                           exposed to TTHMs,
                                                                                           with statistically
                                                                                           significant risk seen
                                                                                           at exposures higher
                                                                                           than 50 ug/L. No
                                                                                           association between
                                                                                           TTHMs and bladder
                                                                                           cancer was seen for
                                                                                           women.
Villanueva et al. 2003 (and      Review and meta-   Compared source    Bladder cancer...  The meta-analysis
 Goebell et al. 2004).            analysis of 6      of water and                          findings showed a
                                  case-control       estimated                             moderate excess risk
                                  studies and 2      duration of                           of bladder cancer
                                  cohort studies.    exposure to                           attributable to long-
                                                     chlorinated                           term consumption of
                                                     drinking water.                       chlorinated drinking
                                                                                           water for both
                                                                                           genders, particularly
                                                                                           in men. Statistically
                                                                                           significance seen
                                                                                           with men and combined
                                                                                           both sexes. The risk
                                                                                           was higher when
                                                                                           exposure exceeded 40
                                                                                           years.

[[Page 398]]

 
Villanueva et al. 2001.........  Qualitative        Compared exposure  Cancer of          Review found that
                                  review of 31       to TTHM levels,    bladder, colon,    although results for
                                  cancer studies.    mutagenic          rectum, and 5      cancer studies varied
                                                     drinking water,    other cancers..    and were not always
                                                     water                                 statistically
                                                     consumption,                          significant, evidence
                                                     source water,                         for bladder cancer is
                                                     types of                              strongest, and all 10
                                                     disinfection                          of the bladder cancer
                                                     (chlorination                         studies showed
                                                     and                                   increased cancer
                                                     chloramination),                      risks with ingestion
                                                     and residence                         of chlorinated water.
                                                     times.                                The authors felt
                                                                                           associations with
                                                                                           chlorinated water and
                                                                                           cancer of the colon,
                                                                                           rectum, pancreas,
                                                                                           esophagus, brain, and
                                                                                           other cancers were
                                                                                           inconsistent.
WHO 2000.......................  Qualitative        Various exposures  Various cancers..  Studies reviewed
                                  reviews of         to THMs..                             reported weak to
                                  various studies                                          moderate increased
                                  in Finland,                                              relative risks of
                                  U.S., and Canada.                                        bladder, colon,
                                                                                           rectal, pancreatic,
                                                                                           breast, brain or lung
                                                                                           cancer associated
                                                                                           with long-term
                                                                                           exposure to
                                                                                           chlorinated drinking
                                                                                           water. The authors
                                                                                           felt evidence is
                                                                                           inconclusive for an
                                                                                           association between
                                                                                           colon cancer and long-
                                                                                           term exposure to
                                                                                           THMs; that evidence
                                                                                           is insufficient to
                                                                                           evaluate a causal
                                                                                           relationship between
                                                                                           THMs and rectal,
                                                                                           bladder, and other
                                                                                           cancers. They found
                                                                                           no association
                                                                                           between THMs and
                                                                                           increased risk of
                                                                                           cardiovascular
                                                                                           disease.
Mills et al. 1998..............  Qualitative        Examined TTHM      Cancer of colon,   Review suggests
                                  review of 22       levels and water   rectum, and        possible increases in
                                  studies.           consumption.       bladder.           risks of bladder
                                                     Compared source                       cancer with exposure
                                                     of water and 2                        to chlorinated
                                                     types of water                        drinking water. The
                                                     treatment                             authors felt evidence
                                                     (chlorination                         for increased risk of
                                                     and                                   colon and rectal
                                                     chloramination).                      cancers is
                                                                                           inconclusive, though
                                                                                           evidence is stronger
                                                                                           for rectal cancer.
----------------------------------------------------------------------------------------------------------------

    Overall, bladder cancer data provide the strongest basis for 
quantifying cancer risks from DBPs. EPA has chosen this endpoint to 
estimate the primary benefits of the Stage 2 DBPR (see Section VI).
    ii. Toxicology. Cancer toxicology studies provide additional 
support that chlorinated water is associated with cancer. In general, 
EPA uses long term toxicology studies that show a dose response to 
derive MCLGs and cancer potency factors. Short term studies are used 
for hazard identification and to design long term studies. Much of the 
available cancer toxicology information was available for the Stage 1 
DBPR, but there have also been a number of new cancer toxicology and 
mode of action studies completed since the Stage 1 DBPR was finalized 
in December 1998.
    In support of this rule, EPA has developed health criteria 
documents which summarize the available toxicology data for brominated 
THMs (USEPA 2005b), brominated HAAs (USEPA 2005c), MX (USEPA 2000b), 
MCAA (USEPA 2005d), and TCAA (USEPA 2005e). The 2003 IRIS assessment of 
DCAA (USEPA 2003b) and an addendum (USEPA 2005k) also provides analysis 
released after Stage 1. It summarizes information on exposure from 
drinking water and develops a slope factor for DCAA. IRIS also has 
toxicological reviews for chloroform (USEPA 2001a), chlorine dioxide 
and chlorite (USEPA 2000c), and bromate (USEPA 2001b), and is currently 
reassessing TCAA.
    Slope factors and risk concentrations for BDCM, bromoform, DBCM and 
DCAA have been developed and are listed in Table II.D-2. For BDCM, 
bromoform, and DBCM, table values are derived from the brominated THM 
criteria document (USEPA 2005b), which uses IRIS numbers that have been 
updated using the 1999 EPA Proposed Guidelines for Carcinogenic Risk 
Assessment (USEPA 1999a). For DCAA, the values are derived directly 
from IRIS.

                                  Table II.D-2.--Quantification of Cancer Risk
----------------------------------------------------------------------------------------------------------------
                                                        LED 10a                             ED 10a
                                         -----------------------------------------------------------------------
         Disinfection byproduct                                10 -6 Risk                          10 -6 Risk
                                            Slope  factor     concentration     Slope  factor     concentration
                                            (mg/kg/day)-1        (mg/L)        (mg/kg/day) -1        (mg/L)
----------------------------------------------------------------------------------------------------------------
Bromodichloromethane....................             0.034             0.001             0.022             0.002
Bromoform...............................            0.0045             0.008            0.0034              0.01
Dibromochloromethane....................              0.04            0.0009             0.017             0.002
Dichloroacetic Acid.....................             0.048            0.0007           0.015 b          0.0023 b
----------------------------------------------------------------------------------------------------------------
a LED10 is the lower 95% confidence bound on the (effective dose) ED10 value. ED10 is the estimated dose
  producing effects in 10% of animals.
b The ED10 risk factors for DCAA have been changed from those given in the comparable table in the proposed
  Stage 2 DBPR to correct for transcriptional errors.

    More research on DBPs is underway at EPA and other research 
institutions. Summaries of on-going studies may be found on EPA's DRINK 
Web site (http://www.epa.gov/safewater/drink/intro.html). Two-year 
bioassays by the National Toxicology Program (NTP) released in abstract 
form have recently been completed on BDCM and chlorate. The draft 
abstract on BDCM reported no evidence of carcinogenicity when BDCM was 
administered via drinking

[[Page 399]]

water (NTP 2005a). Another recent study, a modified two-year bioassay 
on BDCM in the drinking water, reported little evidence of 
carcinogenicity (George et al. 2002). In a previous NTP study, tumors 
were observed, including an increased incidence of kidney, liver, and 
colon tumors, when BDCM was administered at higher doses by gavage in 
corn oil (NTP 1987). EPA will examine new information on BDCM as it 
becomes available. In the chlorate draft abstract, NTP found some 
evidence that it may be a carcinogen (NTP 2004). Chlorate is a 
byproduct of hypochlorite and chlorine dioxide systems. A long-term, 
two-year bioassay NTP study on DBA is also complete but has not yet 
undergone peer review (NTP 2005b).
    b. Reproductive and developmental health effects. Both human 
epidemiology studies and animal toxicology studies have examined 
associations between chlorinated drinking water or DBPs and 
reproductive and developmental health effects. Based on an evaluation 
of the available science, EPA believes the data suggest that exposure 
to DBPs is a potential reproductive and developmental health hazard.
    The following section briefly discusses the reproductive and 
developmental epidemiology and toxicology information available to EPA. 
Further discussion of these studies and EPA's conclusions can be found 
in the proposed Stage 2 DBPR (USEPA 2003a) and the Economic Analysis 
(USEPA 2005a).
    i. Epidemiology. As discussed previously, epidemiology studies have 
the strength of relating human exposure to DBP mixtures through 
multiple intake routes. Although the critical exposure window for 
reproductive and developmental effects is much smaller than that for 
cancer (generally weeks versus years), exposure assessment is also a 
main limitation of reproductive and developmental epidemiology studies. 
Exposure assessment uncertainties arise from limited data on DBP 
concentrations and maternal water usage and source over the course of 
the pregnancy. However, classification errors typically push the true 
risk estimate towards the null value (Vineis 2004). According to Bove 
et al. (2002), ``Difficulties in assessing exposure may result in 
exposure misclassification biases that would most likely produce 
substantial underestimates of risk as well as distorted or attenuated 
exposure-response trends.'' Studies of rare outcomes (e.g., individual 
birth defects) often have limited statistical power because of the 
small number of cases being examined. This limits the ability to detect 
statistically significant associations for small to moderate relative 
risk estimates. Small sample sizes also result in imprecision around 
risk estimates reflected by wide confidence intervals. In addition to 
the limitations of individual studies, evaluating reproductive and 
developmental epidemiology studies collectively is difficult because of 
the methodological differences between studies and the wide variety of 
endpoints examined. These factors may contribute to inconsistencies in 
the scientific body of literature as noted below.
    More recent studies tend to be of higher quality because of 
improved exposure assessments and other methodological advancements. 
For example, studies that use THM levels to estimate exposure tend to 
be higher quality than studies that define exposure by source or 
treatment. These factors were taken into account by EPA when comparing 
and making conclusions on the reproductive and developmental 
epidemiology literature. What follows is a summary of available 
epidemiology literature on reproductive and developmental endpoints 
such as spontaneous abortion, stillbirth, neural tube and other birth 
defects, low birth weight, and intrauterine growth retardation. 
Information is grouped, where appropriate, into three categories on 
fetal growth, viability, and malformations, and reviews are described 
separately afterward. Table II.D-3 provides a more detailed description 
of each study or review.
    Fetal growth. Many studies looked for an association between fetal 
growth (mainly small for gestational age, low birth weight, and pre-
term delivery) and chlorinated water or DBPs. The results from the 
collection of studies as a whole are inconsistent. A number of studies 
support the possibility that exposure to chlorinated water or DBPs are 
associated with adverse fetal growth effects (Infante-Rivard 2004; 
Wright et al. 2004; Wright et al. 2003; K[auml]ll[eacute]n and Robert 
2000; Gallagher et al. 1998; Kanitz et al. 1996; Bove et al. 1995; 
Kramer et al. 1992). Other studies showed mixed results (Porter et al. 
2005; Savitz et al. 2005; Yang 2004) or did not provide evidence of an 
association (Toledano et al. 2005; Jaakkola et al. 2001; Dodds et al. 
1999; Savitz et al. 1995) between DBP exposure and fetal growth. EPA 
notes that recent, higher quality studies provide some evidence of an 
increased risk of small for gestational age and low birth weight.
    Fetal viability. While the database of epidemiology studies for 
fetal loss endpoints (spontaneous abortion or stillbirth) remains 
inconsistent as a whole, there is suggestive evidence of an association 
between fetal loss and chlorinated water or DBP exposure. Various 
studies support the possibility that exposure to chlorinated water or 
DBPs is associated with decreased fetal viability (Toledano et al. 
2005; Dodds et al. 2004; King et al. 2000b; Dodds et al. 1999; Waller 
et al. 1998; Aschengrau et al. 1993; Aschengrau et al. 1989). Other 
studies did not support an association (Bove et al. 1995) or reported 
inconclusive results (Savitz et al. 2005; Swan et al. 1998; Savitz et 
al. 1995) between fetal viability and exposure to THMs or tapwater. A 
recent study by King et al. (2005) found little evidence of an 
association between stillbirths and haloacetic acids after controlling 
for trihalomethane exposures, though non-statistically significant 
increases in stillbirths were seen across various exposure levels.
    Fetal malformations. A number of epidemiology studies have examined 
the relationship between fetal malformations (such as neural tube, oral 
cleft, cardiac, or urinary defects, and chromosomal abnormalities) and 
chlorinated water or DBPs. It is difficult to assess fetal 
malformations in aggregate due to inconsistent findings and disparate 
endpoints being examined in the available studies. Some studies support 
the possibility that exposure to chlorinated water or DBPs is 
associated with various fetal malformations (Cedergren et al. 2002; 
Hwang et al. 2002; Dodds and King 2001; Klotz and Pyrch 1999; Bove et 
al. 1995; Aschengrau et al. 1993). Other studies found little evidence 
(Shaw et al. 2003; K[auml]ll[eacute]n and Robert 2000; Dodds et al. 
1999; Shaw et al. 1991) or inconclusive results (Magnus et al. 1999) 
between chlorinated water or DBP exposure and fetal malformations. 
Birth defects most consistently identified as being associated with 
DBPs include neural tube defects and urinary tract malformations.
    Other endpoints have also been examined in recent epidemiology 
studies. One study suggests an association between DBPs and decreased 
menstrual cycle length (Windham et al. 2003), which, if corroborated, 
could be linked to the biological basis of other reproductive endpoints 
observed. No association between THM exposure and semen quality was 
found (Fenster et al. 2003). More work is needed in both areas to 
support these results.
    Reviews. An early review supported an association between measures 
of fetal viability and tap water (Swan et al.

[[Page 400]]

1992). Three other reviews found data inadequate to support an 
association between reproductive and developmental health effects and 
THM exposure (Reif et al. 1996; Craun 1998; WHO 2000). Mills et al. 
(1998) examined data on and found support for an association between 
fetal viability and malformations and THMs. Another review presented to 
the Stage 2 MDBP FACA found some evidence for an association with fetal 
viability and some fetal malformations and exposure to DBPs but 
reported that the evidence was inconsistent for these endpoints as well 
as for fetal growth (Reif et al. 2000). Reif et al. (2000) concluded 
that the weight of evidence from epidemiology studies suggests that 
``DBPs are likely to be reproductive toxicants in humans under 
appropriate exposure conditions,'' but from a risk assessment 
perspective, data are primarily at the hazard identification stage. 
Nieuwenhuijsen et al. (2000) found some evidence for an association 
between fetal growth and THM exposure and concluded evidence for 
associations with other fetal endpoints is weak but gaining weight. A 
qualitative review by Villanueva et al. (2001) found evidence generally 
supports a possible association between reproductive effects and 
drinking chlorinated water. Graves et al. (2001) supports a possible 
association for fetal growth but not fetal viability or malformations. 
More recently, Bove et al. (2002) examined and supported an association 
between small for gestational age, neural tube defects and spontaneous 
abortion endpoints and DBPs. Following a meta-analysis on five 
malformation studies, Hwang and Jaakkola (2003) concluded that there 
was evidence which supported associations between DBPs and risk of 
birth defects, especially neural tube defects and urinary tract 
defects.

                    Table II.D-3.--Summary of Reproductive/Developmental Epidemiology Studies
----------------------------------------------------------------------------------------------------------------
                                                       Exposure(s)         Outcome(s)
           Author(s)                 Study type          studied            measured             Findings
----------------------------------------------------------------------------------------------------------------
Porter et al. 2005.............  Cross-sectional    Estimated THM and  Intrauterine       No consistent
                                  study in           HAA exposure       growth             association or dose-
                                  Maryland, 1998-    during pregnancy.  retardation.       response relationship
                                  2002.                                                    was found between
                                                                                           exposure to either
                                                                                           TTHM or HAA5 and
                                                                                           intrauterine growth
                                                                                           retardation. Results
                                                                                           suggest an increased
                                                                                           risk of intrauterine
                                                                                           growth retardation
                                                                                           associated with TTHM
                                                                                           and HAA5 exposure in
                                                                                           the third trimester,
                                                                                           although only HAA5
                                                                                           results were
                                                                                           statistically
                                                                                           significant.
Savitz et al. 2005.............  Population-based   Estimated TTHM,    Early and late     No association with
                                  prospective        HAA9, and TOC      pregnancy loss,    pregnancy loss was
                                  cohort study in    exposures during   preterm birth,     seen when looking at
                                  three              pregnancy.         small for          high exposure of TTHM
                                  communities        Indices examined   gestational age,   compared to low
                                  around the U.S.,   included           and term birth     exposure of TTHM.
                                  2000-2004.         concentration,     weight.            When examining
                                                     ingested amount,                      individual THMs, a
                                                     exposure from                         statistically
                                                     showering and                         significant
                                                     bathing, and an                       association was found
                                                     integration of                        between
                                                     all exposures                         bromodichloromethane
                                                     combined.                             (BDCM) and pregnancy
                                                                                           loss. A similar, non-
                                                                                           statistically
                                                                                           significant
                                                                                           association was seen
                                                                                           between
                                                                                           dibromochloromethane
                                                                                           (DBCM) and pregnancy
                                                                                           loss. Some increased
                                                                                           risk was seen for
                                                                                           losses at greater
                                                                                           than 12 weeks'
                                                                                           gestation for TTHM,
                                                                                           BDCM, and TOX (total
                                                                                           organic halide), but
                                                                                           most results
                                                                                           generally did not
                                                                                           provide support for
                                                                                           an association.
                                                                                           Preterm birth showed
                                                                                           a small inverse
                                                                                           relationship with DBP
                                                                                           exposure (i.e. higher
                                                                                           exposures showed less
                                                                                           preterm births), but
                                                                                           this association was
                                                                                           weak. TTHM exposure
                                                                                           of 80 ug/L was
                                                                                           associated with twice
                                                                                           the risk for small
                                                                                           for gestational age
                                                                                           during the third
                                                                                           trimester and was
                                                                                           statistically
                                                                                           significant.
Toledano et al. 2005...........  Large cross-       Linked mother's    Stillbirth, low    A significant
                                  sectional study    residence at       birth weight.      association between
                                  in England, 1992-  time of delivery                      TTHM and risk of
                                  1998.              to modeled                            stillbirth, low birth
                                                     estimates of                          weight, and very low
                                                     TTHM levels in                        birth weight was
                                                     water zones.                          observed in one of
                                                                                           the three regions.
                                                                                           When all three
                                                                                           regions were
                                                                                           combined, small, but
                                                                                           non-significant,
                                                                                           excess risks were
                                                                                           found between all
                                                                                           three outcomes and
                                                                                           TTHM and chloroform.
                                                                                           No associations were
                                                                                           observed between
                                                                                           reproductive risks
                                                                                           and BDCM or total
                                                                                           brominated THMs.
Dodds et al. 2004 (and King et   Population-based   Estimated THM and  Stillbirth.......  A statistically
 al. 2005).                       case-control       HAA exposure at                       significant
                                  study in Nova      residence during                      association was
                                  Scotia and         pregnancy.                            observed between
                                  Eastern Ontario,   Linked water                          stillbirths and
                                  1999-2001.         consumption and                       exposure to total
                                                     showering/                            THM, BDCM, and
                                                     bathing to THM                        chloroform.
                                                     exposure.                             Associations were
                                                                                           also detected for
                                                                                           metrics, which
                                                                                           incorporated water
                                                                                           consumption,
                                                                                           showering and bathing
                                                                                           habits. Elevated
                                                                                           relative risks were
                                                                                           observed for
                                                                                           intermediate
                                                                                           exposures for total
                                                                                           HAA and DCAA
                                                                                           measures; TCAA and
                                                                                           brominated HAA
                                                                                           exposures showed no
                                                                                           association. No
                                                                                           statistically
                                                                                           significant
                                                                                           associations or dose-
                                                                                           response
                                                                                           relationships between
                                                                                           any HAAs and
                                                                                           stillbirth were
                                                                                           detected after
                                                                                           controlling for THM
                                                                                           exposure.

[[Page 401]]

 
Infante-Rivard 2004............  Case-control       Estimated THM      Intrauterine       No associations were
                                  study of           levels and water   growth             found between
                                  newborns in        consumption        retardation.       exposure to THMs and
                                  Montreal, 1998-    during                                intrauterine growth
                                  2000.              pregnancy.                            retardation. However,
                                                     Exposure from                         a significant effect
                                                     showering and                         was observed between
                                                     presence of two                       THM exposure and
                                                     genetic                               intrauterine growth
                                                     polymorphisms.                        retardation for
                                                                                           newborns with the
                                                                                           CYP2E1 gene variant.
                                                                                           Findings suggest that
                                                                                           exposure to THMs at
                                                                                           the highest levels
                                                                                           can affect fetal
                                                                                           growth but only in
                                                                                           genetically
                                                                                           susceptible newborns.
Wright et al. 2004.............  Large cross-       Estimated          Birth weight,      Statistically
                                  sectional study:   maternal third-    small for          significant
                                  Massachusetts,     trimester          gestational age,   reductions in mean
                                  1995-1998.         exposures to       preterm            birth weight were
                                                     TTHMs,             delivery,          observed for BDCM,
                                                     chloroform,        gestational age.   chloroform, and
                                                     BDCM, total                           mutagenic activity.
                                                     HAAs, DCA, TCA,                       An exposure-response
                                                     MX and                                relationship was
                                                     mutagenicity in                       found between THM
                                                     drinking water.                       exposure and
                                                                                           reductions in mean
                                                                                           birth weight and risk
                                                                                           of small for
                                                                                           gestational age.
                                                                                           There was no
                                                                                           association between
                                                                                           preterm delivery and
                                                                                           elevated levels of
                                                                                           HAAs, MX, or
                                                                                           mutagenicity. A
                                                                                           reduced risk of
                                                                                           preterm delivery was
                                                                                           observed with high
                                                                                           THM exposures.
                                                                                           Gestational age was
                                                                                           associated with
                                                                                           exposure to THMs and
                                                                                           mutagenicity.
Yang et al. 2004 (and Yang et    Large cross-       Compared maternal  Low birth weight,  Residence in area
 al. 2000).                       sectional          consumption of     preterm delivery.  supplied with
                                  studies in         chlorinated                           chlorinated drinking
                                  Taiwan, 1994-      drinking water                        water showed a
                                  1996.              (yes/no).                             statistically
                                                                                           significant
                                                                                           association with
                                                                                           preterm delivery. No
                                                                                           association was seen
                                                                                           between chlorinated
                                                                                           drinking water and
                                                                                           low birth weight.
Fenster et al. 2003............  Small prospective  Examined TTHM      Sperm motility,    No association between
                                  study in           levels within      sperm morphology.  TTHM level and sperm
                                  California, 1990-  the 90 days                           mobility or
                                  1991.              preceding semen                       morphology. BDCM was
                                                     collection.                           inversely associated
                                                                                           with linearity of
                                                                                           sperm motion. There
                                                                                           was some suggestion
                                                                                           that water
                                                                                           consumption and other
                                                                                           ingestion metrics may
                                                                                           be associated with
                                                                                           different indicators
                                                                                           of semen quality.
Shaw et al. 2003...............  2 case-control     Estimated THM      Neural tube        No associations or
                                  maternal           levels for         defects, oral      exposure-response
                                  interview          mothers'           clefts, selected   relation were
                                  studies: CA,       residences from    heart defects.     observed between
                                  1987-1991.         before                                malformations and
                                                     conception                            TTHMs in either
                                                     through early                         study.
                                                     pregnancy.
Windham et al. 2003............  Prospective        Estimated          Menstrual cycle,   Findings suggest that
                                  study: CA, 1990-   exposure to THMs   follicular phase   THM exposure may
                                  1991.              through            length (in days).  affect ovarian
                                                     showering and                         function. All
                                                     ingestion over                        brominated THM
                                                     average of 5.6                        compounds were
                                                     menstrual cycles                      associated with
                                                     per woman.                            significantly shorter
                                                                                           menstrual cycles with
                                                                                           the strongest finding
                                                                                           for
                                                                                           chlorodibromomethane.
                                                                                           There was little
                                                                                           association between
                                                                                           TTHM exposure and
                                                                                           luteal phase length,
                                                                                           menses length, or
                                                                                           cycle variability.
Wright et al. 2003.............  Cross-sectional    Estimated TTHM     Birth weight,      Statistically
                                  study:             exposure in        small for          significant
                                  Massachusetts,     women during       gestational age,   associations between
                                  1990.              pregnancy          preterm            2nd trimester and
                                                     (average for       delivery,          pregnancy average
                                                     pregnancy and      gestational age.   TTHM exposure and
                                                     during each                           small for gestational
                                                     trimester).                           age and fetal birth
                                                                                           weight were detected.
                                                                                           Small, statistically
                                                                                           significant increases
                                                                                           in gestational
                                                                                           duration/age were
                                                                                           observed at increased
                                                                                           TTHM levels, but
                                                                                           there was little
                                                                                           evidence of an
                                                                                           association between
                                                                                           TTHM and preterm
                                                                                           delivery or low birth
                                                                                           weight.
Cedergren et al. 2002..........  Retrospective      Examined maternal  Cardiac defects..  Exposure to chlorine
                                  case-control       periconceptional                      dioxide in drinking
                                  study: Sweden,     DBP levels and                        water showed
                                  1982-1997.         used GIS to                           statistical
                                                     assign water                          significance for
                                                     supplies.                             cardiac defects. THM
                                                                                           concentrations of 10
                                                                                           ug/L and higher were
                                                                                           significantly
                                                                                           associated with
                                                                                           cardiac defects. No
                                                                                           excess risk for
                                                                                           cardiac defect and
                                                                                           nitrate were seen.
Hwang et al. 2002..............  Large cross-       Compared exposure  Birth defects      Risk of any birth
                                  sectional study    to chlorination    (neural tube       defect, cardiac,
                                  in Norway, 1993-   (yes/no) and       defects,           respiratory system,
                                  1998.              water color        cardiac,           and urinary tract
                                                     levels for         respiratory        defects were
                                                     mother's           system, oral       significantly
                                                     residence during   cleft, urinary     associated with water
                                                     pregnancy.         tract).            chlorination.
                                                                                           Exposure to
                                                                                           chlorinated drinking
                                                                                           water was
                                                                                           statistically
                                                                                           significantly
                                                                                           associated with risk
                                                                                           of ventricular septal
                                                                                           defects, and an
                                                                                           exposure-response
                                                                                           pattern was seen. No
                                                                                           other specific
                                                                                           defects were
                                                                                           associated with the
                                                                                           exposures that were
                                                                                           examined.

[[Page 402]]

 
Dodds and King 2001............  Population-based   Estimated THM,     Neural tube        Exposure to BDCM was
                                  retrospective      chloroform, and    defects,           associated with
                                  cohort in Nova     bromodichloromet   cardiovascular     increased risk of
                                  Scotia, 1988-      hane (BDCM)        defects, cleft     neural tube defects,
                                  1995.              exposure.          defects,           cardiovascular
                                                                        chromosomal        anomalies. Chloroform
                                                                        abnormalities.     was not associated
                                                                                           with neural tube
                                                                                           defects, but was
                                                                                           associated with
                                                                                           chromosomal
                                                                                           abnormalities. No
                                                                                           association between
                                                                                           THM and cleft defects
                                                                                           were detected.
Jaakkola et al. 2001...........  Large cross-       Compared           Low birth weight,  No evidence found for
                                  sectional study    chlorination       small for          association between
                                  in Norway, 1993-   (yes/no) and       gestational age,   prenatal exposure to
                                  1995.              water color        preterm delivery.  chlorinated drinking
                                                     (high/low) for                        water and low birth
                                                     mother during                         weight or small for
                                                     pregnancy.                            gestational age. A
                                                                                           reduced risk of
                                                                                           preterm delivery was
                                                                                           noted for exposure to
                                                                                           chlorinated water
                                                                                           with high color
                                                                                           content.
K[auml]ll[eacute]n and Robert    Large cross-       Linked prenatal    Gestational        A statistically
 2000.                            sectional cohort   exposure to        duration, birth    significant
                                  study in Sweden,   drinking water     weight,            difference was found
                                  1985-1994.         disinfected with   intrauterine       for short gestational
                                                     various methods    growth,            duration and low
                                                     (no chlorine,      mortality,         birth weight among
                                                     chlorine dioxide   congenital         infants whose mother
                                                     only, sodium       malformations,     resided in areas
                                                     hypochlorite       and other birth    using sodium
                                                     only).             outcomes.          hypochlorite, but not
                                                                                           for chlorine dioxide.
                                                                                           Sodium hypochlorite
                                                                                           was also associated
                                                                                           with other indices of
                                                                                           fetal development but
                                                                                           not with congenital
                                                                                           defects. No other
                                                                                           effects were observed
                                                                                           for intrauterine
                                                                                           growth, childhood
                                                                                           cancer, infant
                                                                                           mortality, low Apgar
                                                                                           score, neonatal
                                                                                           jaundice, or neonatal
                                                                                           hypothyroidism in
                                                                                           relation to either
                                                                                           disinfection method.
Dodds et al. 1999 (and King et   Population-based   Estimated TTHM     Low birth weight,  A statistically
 al. 2000b).                      retrospective      level for women    preterm birth,     significant increased
                                  cohort study in    during pregnancy.  small for          risk for stillbirths
                                  Nova Scotia,                          gestational age,   and high total THMs
                                  1988-1995.                            stillbirth,        and specific THMs
                                                                        chromosomal        during pregnancy was
                                                                        abnormalities,     detected, with higher
                                                                        neural tube        risks observed among
                                                                        defects, cleft     asphyxia-related
                                                                        defects, major     stillbirths.
                                                                        cardiac defects.   Bromodichloromethane
                                                                                           had the strongest
                                                                                           association and
                                                                                           exhibited an exposure-
                                                                                           response pattern.
                                                                                           There was limited
                                                                                           evidence of an
                                                                                           association between
                                                                                           THM level and other
                                                                                           reproductive
                                                                                           outcomes. No
                                                                                           congenital anomalies
                                                                                           were associated with
                                                                                           THM exposure, except
                                                                                           for a non-
                                                                                           statistically
                                                                                           significant
                                                                                           association with
                                                                                           chromosomal
                                                                                           abnormalities.
Klotz and Pyrch 1999 (and Klotz  Population-based   Estimated          Neural tube        A significant
 and Pyrch 1998).                 case-control       exposure of        defects.           association was seen
                                  study in New       pregnant mothers                      between exposure to
                                  Jersey, 1993-      to TTHMs and                          THMs and neural tube
                                  1994.              HAAs, and                             defects. No
                                                     compared source                       associations were
                                                     of water.                             observed for neural
                                                                                           tube defects and
                                                                                           haloacetic acids or
                                                                                           haloacetonitriles.
Magnus et al. 1999.............  Large cross-       Compared           Birth defects      Statistically
                                  sectional study    chlorination       (neural tube       significant
                                  in Norway, 1993-   (yes/no) and       defects, major     associations were
                                  1995.              water color        cardiac,           seen between urinary
                                                     (high/low) at      respiratory,       tract defects and
                                                     mothers'           urinary, oral      chlorination and high
                                                     residences at      cleft).            water color (high
                                                     time of birth.                        content of organic
                                                                                           compounds). No
                                                                                           associations were
                                                                                           detected for other
                                                                                           outcomes or all birth
                                                                                           defects combined. A
                                                                                           non-statistically
                                                                                           significant, overall
                                                                                           excess risk of birth
                                                                                           defects was seen
                                                                                           within municipalities
                                                                                           with chlorination and
                                                                                           high water color
                                                                                           compared to
                                                                                           municipalities with
                                                                                           no chlorination and
                                                                                           low color.
Gallagher et al. 1998..........  Retrospective      Estimated THM      Low birth weight,  Weak, non-
                                  cohort study of    levels in          term low           statistically
                                  newborns in        drinking water     birthweight, and   significant
                                  Colorado, 1990-    during third       preterm delivery.  association with low
                                  1993.              trimester of                          birth weight and TTHM
                                                     pregnancy.                            exposure during the
                                                                                           third trimester.
                                                                                           Large statistically
                                                                                           significant increase
                                                                                           for term low
                                                                                           birthweight at
                                                                                           highest THM exposure
                                                                                           levels. No
                                                                                           association between
                                                                                           preterm delivery and
                                                                                           THM exposure.
Swan et al. 1998...............  Prospective study  Compared           Spontaneous        Pregnant women who
                                  in California,     consumption of     abortion.          drank cold tap water
                                  1990-1991.         cold tap water                        compared to those who
                                                     to bottled water                      consumed no cold tap
                                                     during early                          water showed a
                                                     pregnancy.                            significant finding
                                                                                           for spontaneous
                                                                                           abortion at one of
                                                                                           three sites.

[[Page 403]]

 
Waller et al. 1998 (and Waller   Prospective        Estimated TTHM     Spontaneous        Statistically
 et al. 2001).                    cohort in          levels during      abortion.          significant increased
                                  California, 1989-  first trimester                       risk between high
                                  1991.              of pregnancy via                      intake of TTHMs and
                                                     ingestion and                         spontaneous abortion
                                                     showering.                            compared to low
                                                                                           intake. BDCM
                                                                                           statistically
                                                                                           associated with
                                                                                           increased spontaneous
                                                                                           abortion; other THMs
                                                                                           not. Reanalysis of
                                                                                           exposure yielded less
                                                                                           exposure
                                                                                           misclassification and
                                                                                           relative risks
                                                                                           similar in magnitude
                                                                                           to earlier study. An
                                                                                           exposure-response
                                                                                           relationship was seen
                                                                                           between spontaneous
                                                                                           abortion and
                                                                                           ingestion exposure to
                                                                                           TTHMs.
Kanitz et al. 1996.............  Cross-sectional    Compared 3 types   Low birth weight,  Smaller body length
                                  study in Italy,    of water           body length,       and small cranial
                                  1988-1989.         treatment          cranial            circumference showed
                                                     (chlorine          circumference,     statistical
                                                     dioxide, sodium    preterm            significant
                                                     hypochlorite,      delivery, and      association with
                                                     and chlorine       other effects.     maternal exposure to
                                                     dioxide/sodium                        chlorinated drinking
                                                     hypochlorite).                        water. Neonatal
                                                                                           jaundice linked
                                                                                           statistically to
                                                                                           prenatal exposure to
                                                                                           drinking water
                                                                                           treated with chlorine
                                                                                           dioxide. Length of
                                                                                           pregnancy, type of
                                                                                           delivery, and
                                                                                           birthweight showed no
                                                                                           association.
Bove et al. 1995 (and Bove et    Large cohort       Examined maternal  Low birth weight,  Weak, statistically
 al. 1992a & 1992b).              cross-sectional    exposure to TTHM   fetal deaths,      significant increased
                                  study in New       and various        small for          risk found for higher
                                  Jersey, 1985-      other              gestational age,   TTHM levels with
                                  1988.              contaminants.      birth defects      small for gestational
                                                                        (neural tube       age, neural tube
                                                                        defects, oral      defects, central
                                                                        cleft, central     nervous system
                                                                        nervous system,    defects, oral cleft
                                                                        major cardiac).    defects, and major
                                                                                           cardiac defects. Some
                                                                                           association with
                                                                                           higher TTHM exposure
                                                                                           and low birth weight.
                                                                                           No effect seen for
                                                                                           preterm birth, very
                                                                                           low birth weight, or
                                                                                           fetal deaths.
Savitz et al. 1995.............  Population-based   Examined TTHM      Spontaneous        There was a
                                  case-control       concentration at   abortion,          statistically
                                  study: North       residences and     preterm            significant increased
                                  Carolina, 1988-    water              delivery, low      miscarriage risk with
                                  1991.              consumption        birth weight.      high THM
                                                     (during first                         concentration, but
                                                     and third                             THM intake (based on
                                                     trimesters).                          concentration times
                                                                                           consumption level)
                                                                                           was not related to
                                                                                           pregnancy outcome. No
                                                                                           associations were
                                                                                           seen for preterm
                                                                                           delivery or low birth
                                                                                           weight. Water source
                                                                                           was not related to
                                                                                           pregnancy outcome
                                                                                           either, with the
                                                                                           exception of a non-
                                                                                           significant,
                                                                                           increased risk of
                                                                                           spontaneous abortion
                                                                                           for bottled water
                                                                                           users. There was a
                                                                                           non-statistically
                                                                                           significant pattern
                                                                                           of reduced risk with
                                                                                           increased consumption
                                                                                           of water for all
                                                                                           three outcomes.
Aschengrau et al. 1993.........  Case-control       Source of water    Neonatal death,    There was a non-
                                  study in           and 2 types of     stillbirth,        significant,
                                  Massachusetts,     water treatment    congenital         increased association
                                  1977-1980.         (chlorination,     anomalies.         between frequency of
                                                     chloramination).                      stillbirths and
                                                                                           maternal exposure to
                                                                                           chlorinated versus
                                                                                           chloraminated surface
                                                                                           water. An increased
                                                                                           risk of urinary track
                                                                                           and respiratory track
                                                                                           defects and
                                                                                           chlorinated water was
                                                                                           detected. Neonatal
                                                                                           death and other major
                                                                                           malformations showed
                                                                                           no association. No
                                                                                           increased risk seen
                                                                                           for any adverse
                                                                                           pregnancy outcomes
                                                                                           for surface water
                                                                                           versus ground and
                                                                                           mixed water use.
Kramer et al. 1992.............  Population-based   Examined           Low birth weight,  Statistically
                                  case-control       chloroform,        prematurity,       significant increased
                                  study in Iowa,     DCBM, DBCM, and    intrauterine       risk for intrauterine
                                  1989-1990.         bromoform levels   growth             growth retardation
                                                     and compared       retardation.       effects from
                                                     type of water                         chloroform exposure
                                                     source (surface,                      were observed. Non-
                                                     shallow well,                         significant increased
                                                     deep well).                           risks were observed
                                                                                           for low birth weight
                                                                                           and chloroform and
                                                                                           for intrauterine
                                                                                           growth retardation
                                                                                           and DCBM. No
                                                                                           intrauterine growth
                                                                                           retardation or low
                                                                                           birth weight effects
                                                                                           were seen for the
                                                                                           other THMs, and no
                                                                                           effects on
                                                                                           prematurity were
                                                                                           observed for any of
                                                                                           the THMs.
Shaw et al. 1991 (and Shaw et    Small case-        Estimated          Congenital         Following reanalysis,
 al. 1990).                       control study:     chlorinated tap    cardiac            no association
                                  Santa Clara        water              anomalies.         between cardiac
                                  County, CA, 1981-  consumption,                          anomalies and TTHM
                                  1983.              mean maternal                         level were observed.
                                                     TTHM level,
                                                     showering/
                                                     bathing exposure
                                                     at residence
                                                     during first
                                                     trimester.
Aschengrau et al. 1989.........  Case-control       Source of water    Spontaneous        A statistically
                                  study in           and exposure to    abortion.          significantly
                                  Massachusetts,     metals and other                      association was
                                  1976-1978.         contaminants.                         detected between
                                                                                           surface water source
                                                                                           and frequency of
                                                                                           spontaneous abortion.

[[Page 404]]

 
     Reviews/Meta-analyses
Hwang and Jakkola 2003.........  Review and meta-   Compared DBP       Birth defects      The meta-analysis
                                  analysis of 5      levels, source     (respiratory       supports an
                                  studies.           of water,          system, urinary    association between
                                                     chlorine           system, neural     exposure to
                                                     residual, color    tube defects,      chlorination by-
                                                     (high/low), and    cardiac, oral      products and the risk
                                                     2 types of         cleft).            of any birth defect,
                                                     disinfection:                         particularly the risk
                                                     chlorination and                      of neural tube
                                                     chloramination.                       defects and urinary
                                                                                           system defects.
Bove et al. 2002...............  Qualitative        Examined THM       Birth defects,     Review found the
                                  review of 14       levels. Compared   small for          studies of THMs and
                                  studies.           drinking water     gestational age,   adverse birth
                                                     source and type    low birth          outcomes provide
                                                     of water           weight, preterm    moderate evidence for
                                                     treatment.         delivery,          associations with
                                                                        spontaneous        small for gestational
                                                                        abortion, fetal    age, neural tube
                                                                        death.             defects, and
                                                                                           spontaneous
                                                                                           abortions. Authors
                                                                                           felt risks may have
                                                                                           been underestimated
                                                                                           and exposure-response
                                                                                           relationships
                                                                                           distorted due to
                                                                                           exposure
                                                                                           misclassification.
Graves et al. 2001.............  Review of          Examined water     Low birth weight,  Weight of evidence
                                  toxicological      consumption,       preterm            suggested positive
                                  and                duration of        delivery, small    association with DBP
                                  epidemiological    exposure, THM      for gestational    exposure for growth
                                  studies using a    levels, HAA        age,               retardation such as
                                  weight of          levels, and        intrauterine       small for gestational
                                  evidence           other              growth             age or intrauterine
                                  approach.          contaminants.      retardation,       growth retardation
                                                     Compared source    specific birth     and urinary tract
                                                     of water, water    defects,           defects. Review found
                                                     treatment, water   neonatal death,    no support for DBP
                                                     color (high/       decreased          exposure and low
                                                     low), etc.         fertility, fetal   birth weight, preterm
                                                                        resorption, and    delivery, some
                                                                        other effects.     specific birth
                                                                                           defects, and neonatal
                                                                                           death, and
                                                                                           inconsistent findings
                                                                                           for all birth
                                                                                           defects, all central
                                                                                           nervous system
                                                                                           defects, neural tube
                                                                                           defects, spontaneous
                                                                                           abortion, and
                                                                                           stillbirth.
Villanueva et al. 2001.........  Qualitative        Compared exposure  Spontaneous        Review found positive
                                  review of 14       to TTHM levels,    abortion, low      associations between
                                  reproductive and   mutagenic          birth weight,      increased spontaneous
                                  developmental      drinking water,    small for          abortion, low birth
                                  health effect      water              gestational age,   weight, small for
                                  studies.           consumption,       neural tube        gestational age, and
                                                     source water,      defects, other     neural tube defects
                                                     types of           reproductive and   and drinking
                                                     disinfection       developmental      chlorinated water in
                                                     (chlorination      outcomes.          most studies,
                                                     and                                   although not always
                                                     chloramination),                      with statistical
                                                     and residence                         significance.
                                                     times.
Nieuwenhuijsen et al. 2000.....  Qualitative        Examined levels    Low birth weight,  The review supports
                                  review of          of various DBPs,   preterm            some evidence of
                                  numerous           water              delivery,          association between
                                  toxicological      consumption, and   spontaneous        THMs and low birth
                                  and                duration of        abortions,         weight, but
                                  epidemiological    exposure.          stillbirth,        inconclusive. Review
                                  studies.           Compared water     birth defects,     found no evidence of
                                                     color, water       etc.               association between
                                                     treatment,                            THMs and preterm
                                                     source of water,                      delivery, and that
                                                     etc.                                  associations for
                                                                                           other outcomes
                                                                                           (spontaneous
                                                                                           abortions,
                                                                                           stillbirth, and birth
                                                                                           defects) were weak
                                                                                           but gaining weight.
Reif et al. 2000...............  Qualitative        Compared source    Birth weight, low  Weight of evidence
                                  reviews of         of water supply    birth weight,      suggested DBPs are
                                  numerous           and methods of     intrauterine       reproductive
                                  epidemiological    disinfection.      growth             toxicants in humans
                                  studies.           Estimated TTHM     retardation,       under appropriate
                                                     levels.            small for          exposure conditions.
                                                                        gestational age,   The review reports
                                                                        preterm deliver,   findings between
                                                                        somatic            TTHMs and effects on
                                                                        parameters,        fetal growth, fetal
                                                                        neonatal           viability, and
                                                                        jaundice,          congenital anomalies
                                                                        spontaneous        as inconsistent.
                                                                        abortion,          Reviewers felt data
                                                                        stillbirth,        are at the stage of
                                                                        developmental      hazard identification
                                                                        anomalies.         and did not suggest a
                                                                                           dose-response pattern
                                                                                           of increasing risk
                                                                                           with increasing TTHM
                                                                                           concentration.
WHO 2000.......................  Qualitative        Various exposures  Various            Review found some
                                  reviews of         to THMs.           reproductive and   support for an
                                  various studies                       developmental      association between
                                  in Finland,                           effects.           increased risks of
                                  U.S., and Canada.                                        neural tube defects
                                                                                           and miscarriage and
                                                                                           THM exposure. Other
                                                                                           associations have
                                                                                           been observed, but
                                                                                           the authors believed
                                                                                           insufficient data
                                                                                           exist to assess any
                                                                                           of these
                                                                                           associations.
Craun, ed. 1998................  Qualitative        Examined THM       Stillbirth,        Associations between
                                  review of 10       levels and water   neonatal death,    DBPs and various
                                  studies, focus     consumption, and   spontaneous        reproductive effects
                                  on California      compared source    abortion, low      were seen in some
                                  cohort study.      of water and       birth weight,      epidemiological
                                                     water treatment    preterm            studies, but the
                                                     (chlorine,         delivery,          authors felt these
                                                     chloramines,       intrauterine       results do not
                                                     chlorine           growth             provide convincing
                                                     dioxide).          retardation,       evidence for a causal
                                                                        neonatal           relationship between
                                                                        jaundice, birth    DBPs and reproductive
                                                                        defects.           effects.

[[Page 405]]

 
Mills et al. 1998..............  Qualitative        Examined TTHM      Various            Review found studies
                                  review of 22       levels and water   reproductive and   suggest possible
                                  studies.           consumption.       developmental      increases in adverse
                                                     Compared source    effects.           reproductive and
                                                     of water and 2                        developmental
                                                     types of water                        effects, such as
                                                     treatment                             increased spontaneous
                                                     (chlorination                         abortion rates, small
                                                     and                                   for gestational age,
                                                     chloramination).                      and fetal anomalies,
                                                                                           but that insufficient
                                                                                           evidence exists to
                                                                                           establish a causal
                                                                                           relationship.
Reif et al. 1996...............  Review of 3 case-  Examined THM       Birth defects      Studies reviewed
                                  control studies    levels at          (central nervous   suggest that exposure
                                  and 1 cross-       residences, dose   system, neural     to DBPs may increase
                                  sectional study.   consumption,       tube defects,      intrauterine growth
                                                     chloroform.        cardiac, oral      retardation, neural
                                                     Compared source    cleft,             tube defects, major
                                                     of waters and 2    respiratory,       heart defects, and
                                                     types of water     urinary tract),    oral cleft defects.
                                                     treatment          spontaneous        Review found
                                                     (chlorination      abortion, low      epidemiologic
                                                     and                birth weight,      evidence supporting
                                                     chloramination).   growth             associations between
                                                                        retardation,       exposure to DBPs and
                                                                        preterm            adverse pregnancy
                                                                        delivery,          outcomes to be sparse
                                                                        intrauterine       and to provide an
                                                                        growth             inadequate basis to
                                                                        retardation,       identify DBPs as a
                                                                        stillbirth,        reproductive or
                                                                        neonatal death.    developmental hazard.
Swan et al. 1992...............  Qualitative        Compared maternal  Spontaneous        Four of the studies
                                  review of 5        consumption of     abortion.          reviewed suggest that
                                  studies in Santa   residence tap                         women drinking
                                  Clara County, CA   water to bottled                      bottled water during
                                  (Deane et al.      water.                                the first trimester
                                  1992, Wrensch et                                         of pregnancy may have
                                  al. 1992, Hertz-                                         reduced risk of
                                  Picciotto et al.                                         spontaneous abortion
                                  1992, Windham et                                         relative to drinking
                                  al. 1992,                                                tap water. No
                                  Fenster et al.                                           association seen in
                                  1992).                                                   the fifth study.
                                                                                           Review concluded that
                                                                                           if findings are
                                                                                           causal and not due to
                                                                                           chance or bias, data
                                                                                           suggest a 10-50%
                                                                                           increase in
                                                                                           spontaneous abortion
                                                                                           risk for pregnant
                                                                                           women drinking tap
                                                                                           water over bottled
                                                                                           water.
----------------------------------------------------------------------------------------------------------------

    ii. Toxicology. To date, the majority of reproductive and 
developmental toxicology studies have been short term and higher dose. 
Many of these studies are summarized in a review by Tyl (2000). A 
summary of this review and of additional studies is provided in the 
proposed Stage 2 DBPR (USEPA 2003a). Individual DBP supporting 
documents evaluate and assess additional studies as well (USEPA 2000b; 
USEPA 2000c; USEPA 2001a; USEPA 2001b; USEPA 2003b; USEPA 2005b; USEPA 
2005c; USEPA 2005d; USEPA 2005e; USEPA 2005k). A number of recent 
studies have been published that include in vivo and in vitro assays to 
address mechanism of action. Overall, reproductive and developmental 
toxicology studies indicate a possible reproductive/developmental 
health hazard although they are preliminary in nature for the majority 
of DBPs, and the dose-response characteristics of most DBPs have not 
been quantified. Some of the reproductive effects of DCAA were 
quantified as part of the RfD development process, and impacts of DCAA 
on testicular structure are one of the critical effects in the study 
that is the basis of the RfD (USEPA 2003b).
    A few long term, lower dose studies have been completed. Christian 
et al. (2002a and 2002b) looked for an association between BDCM and 
DBAA and reproductive and developmental endpoints. The authors 
identified a NOAEL and LOAEL of 50 ppm and 150 ppm, respectively, based 
on delayed sexual maturation for BDCM and a NOAEL and LOAEL of 50 ppm 
and 250 ppm based on abnormal spermatogenesis for DBAA. The authors 
concluded that similar effects in humans would only be seen at levels 
many orders of magnitude higher than that of current drinking water 
levels. As discussed in more detail in the proposal, EPA believes that 
because of key methodological differences indicated as being important 
in other studies (Bielmeier et al. 2001; Bielmeier et al. 2004; Kaydos 
et al. 2004; Klinefelter et al. 2001; Klinefelter et al. 2004), 
definitive conclusions regarding BDCM and DBAA cannot be drawn. Other 
multi-generation research underway includes a study on BCAA, but this 
research is not yet published.
    Biological plausibility for the effects observed in reproductive 
and developmental epidemiological studies has been demonstrated through 
various toxicological studies on some individual DBPs (e.g., Bielmeier 
et al. 2001; Bielmeier et al. 2004; Narotsky et al. 1992; Chen et al. 
2003; Chen et al. 2004). Some of these studies were conducted at high 
doses, but similarity of effects observed between toxicology studies 
and epidemiology studies strengthens the weight of evidence for a 
possible association between adverse reproductive and developmental 
health effects and exposure to chlorinated surface water.
    c. Conclusions. EPA's weight of evidence evaluation of the best 
available science on carcinogenicity and reproductive and developmental 
effects, in conjunction with the widespread exposure to DBPs, supports 
the incremental regulatory changes in today's rule that target lowering 
DBPs and providing equitable public health protection.
    EPA believes that the cancer epidemiology and toxicology literature 
provide important information that contributes to the weight of 
evidence for potential health risks from exposure to chlorinated 
drinking water. At this time, the cancer epidemiology studies support a 
potential association between exposure to chlorinated drinking water 
and cancer, but evidence is insufficient to establish a causal 
relationship. The epidemiological evidence for an association between 
DBP exposure and colon and rectal cancers is not as consistent as it is 
for bladder cancer, although similarity of effects reported in animal 
toxicity and human epidemiology studies strengthens the evidence for an 
association with colon and rectal cancers. EPA believes that the 
overall cancer epidemiology and toxicology data support the decision to

[[Page 406]]

pursue additional DBP control measures as reflected in the Stage 2 
DBPR.
    Based on the weight of evidence evaluation of the reproductive and 
developmental epidemiology data, EPA concludes that a causal link 
between adverse reproductive or developmental health effects and 
exposure to chlorinated drinking water or DBPs has not been 
established, but that there is a potential association. Despite 
inconsistent findings across studies, some recent studies continue to 
suggest associations between DBP exposure and various adverse 
reproductive and developmental effects. In addition, data from a number 
of toxicology studies, although the majority of them were conducted 
using high doses, demonstrate biological plausibility for some of the 
effects observed in epidemiology studies. EPA concludes that no dose-
response relationship or causal link has been established between 
exposure to chlorinated drinking water or disinfection byproducts and 
adverse developmental or reproductive health effects. EPA's evaluation 
of the best available studies, particularly epidemiology studies is 
that they do not support a conclusion at this time as to whether 
exposure to chlorinated drinking water or disinfection byproducts 
causes adverse developmental and reproductive health effects, but do 
provide an indication of a potential health concern that warrants 
incremental regulatory action beyond the Stage 1 DBPR.

D. DBP Occurrence and DBP Control

    New information on the occurrence of DBPs in distribution systems 
raises issues about the protection provided by the Stage 1 DBPR. This 
section presents new occurrence and treatment information used to 
identify key issues and to support the development of the Stage 2 DBPR. 
For a more detailed discussion see the proposed Stage 2 DBPR (USEPA 
2003a). For additional information on occurrence of regulated and 
nonregulated DBPs, see the Occurrence Assessment for the Final Stage 2 
Disinfectants and Disinfection Byproducts Rule (USEPA 2005f).
1. Occurrence
    EPA, along with the M-DBP Advisory Committee, collected, developed, 
and evaluated new information that became available after the Stage 1 
DBPR was published. The Information Collection Rule (ICR) (USEPA 1996) 
provided new field data on DBP exposure for large water systems and new 
study data on the effectiveness of several DBP control technologies. 
The unprecedented amount of information collected under the ICR was 
supplemented by a survey conducted by the National Rural Water 
Association, data provided by various States, the Water Utility 
Database (which contains data collected by the American Water Works 
Association), and ICR Supplemental Surveys for small and medium water 
systems.
    After analyzing the DBP occurrence data, EPA and the Advisory 
Committee reached three significant conclusions that in part led the 
Advisory Committee to recommend further control of DBPs in public water 
systems. First, the data from the Information Collection Rule showed 
that the RAA compliance calculation under the Stage 1 DBPR allows 
elevated TTHM or HAA5 levels to regularly occur at some locations in 
the distribution system while the overall average of TTHM or HAA5 
levels at all DBP monitoring locations is below the MCLs of the Stage 1 
DBPR. Customers served at those sampling locations with DBP levels that 
are regularly above 0.080 mg/L TTHM and 0.060 mg/L HAA5 experience 
higher exposure compared to customers served at locations where these 
levels are consistently met.
    Second, the new data demonstrated that DBP levels in single samples 
can be substantially above 0.080 mg/L TTHM and 0.060 mg/L HAA5. Some 
customers receive drinking water with concentrations of TTHM and HAA5 
up to 75% above 0.080 mg/L and 0.060 mg/L, respectively, even when 
their water system is in compliance with the Stage 1 DBPR. Some studies 
support an association between acute exposure to DBPs and potential 
adverse reproductive and developmental health effects (see Section 
III.C for more detail).
    Third, the data from the Information Collection Rule revealed that 
the highest TTHM and HAA5 levels can occur at any monitoring site in 
the distribution system. In fact, the highest concentrations did not 
occur at the maximum residence time locations in more than 50% of all 
ICR samples. The fact that the locations with the highest DBP levels 
vary in different public water systems indicates that the Stage 1 DBPR 
monitoring may not accurately represent the high DBP concentrations 
that actually exist in distribution systems, and that additional 
monitoring is needed to identify distribution system locations with 
elevated DBP levels.
    These data showed that efforts beyond the Stage 1 DBPR are needed 
to provide more equitable protection from DBP exposure across the 
entire distribution system. The incremental regulatory changes made 
under the Stage 2 DBPR meet this need by reevaluating the locations of 
DBP monitoring sites and addressing high DBP concentrations that occur 
at particular locations or in single samples within systems in 
compliance.
2. Treatment
    The analysis of the new treatment study data confirmed that certain 
technologies are effective at reducing DBP concentrations. Bench- and 
pilot-scale studies for granular activated carbon (GAC) and membrane 
technologies required by the Information Collection Rule provided 
information on the effectiveness of the two technologies. Other studies 
found UV light to be highly effective for inactivating Cryptosporidium 
and Giardia at low doses without promoting the formation of DBPs 
(Malley et al. 1996; Zheng et al. 1999). This new treatment information 
adds to the treatment options available to utilities for controlling 
DBPs beyond the requirements of the Stage 1 DBPR.

E. Conclusions for Regulatory Action

    After extensive analysis of available data and rule options 
considered by the Advisory Committee and review of public comments on 
the proposed Stage 2 DBPR (USEPA, 2003a), EPA is finalizing a Stage 2 
DBPR control strategy consistent with the key elements of the Agreement 
in Principle signed in September 2000 by the participants in the Stage 
2 M-DBP Advisory Committee. EPA believes that exposure to chlorinated 
drinking water may be associated with cancer, reproductive, and 
developmental health risks. EPA determined that the risk-targeting 
measures recommended in the Agreement in Principle will require only 
those systems with the greatest risk to make treatment and operational 
changes and will maintain simultaneous protection from potential health 
concerns from DBPs and microbial contaminants. EPA has carefully 
evaluated and expanded upon the recommendations of the Advisory 
Committee and public comments to develop today's rule. EPA also made 
simplifications where possible to minimize complications for public 
water systems as they transition to compliance with the Stage 2 DBPR 
while expanding public health protection. The requirements of the Stage 
2 DBPR are described in detail in Section IV of this preamble.

IV. Explanation of Today's Action

A. MCLGs

    MCLGs are set at concentration levels at which no known or 
anticipated adverse health effects occur, allowing for an adequate 
margin of safety.

[[Page 407]]

Establishment of an MCLG for each specific contaminant is based on the 
available evidence of carcinogenicity or noncancer adverse health 
effects from drinking water exposure using EPA's guidelines for risk 
assessment. MCLGs are developed to ensure they are protective of the 
entire population.
    Today's rule provides MCLGs for chloroform and two haloacetic 
acids, monochloroacetic acid (MCAA) and trichloroacetic acid (TCAA).
1. Chloroform MCLG
    a. Today's rule. The final MCLG for chloroform is 0.07 mg/L. The 
MCLG was calculated using toxicological evidence that the carcinogenic 
effects of chloroform are due to sustained tissue toxicity. EPA is not 
changing the other THM MCLGs finalized in the Stage 1 DBPR.
    b. Background and analysis. The MCLG for chloroform is unchanged 
from the proposal. The MCLG is calculated using a reference dose (RfD) 
of 0.01 mg/kg/day and an adult tap water consumption of 2 L per day for 
a 70 kg adult. A relative source contribution (RSC) of 20% was used in 
accordance with Office of Water's current approach for deriving RSC 
through consideration of data that indicate that other routes and 
sources of exposure may potentially contribute substantially to the 
overall exposure to chloroform. See the proposed Stage 2 DBPR (USEPA 
2003a) for a detailed discussion of the chloroform MCLG.
[GRAPHIC] [TIFF OMITTED] TR04JA06.003

    Based on an analysis of the available scientific data on 
chloroform, EPA believes that the chloroform dose-response is nonlinear 
and that chloroform is likely to be carcinogenic only under high 
exposure conditions (USEPA 2001a). This assessment is supported by the 
principles of the 1999 EPA Proposed Guidelines for Carcinogen Risk 
Assessment (USEPA 1999a) and reconfirmed by the 2005 final Cancer 
Guidelines (USEPA 2005i). The science in support of a nonlinear 
approach for estimating the carcinogenicity of chloroform was affirmed 
by the Chloroform Risk Assessment Review Subcommittee of the EPA SAB 
Executive Committee (USEPA 2000d). Since the nonzero MCLG is based on a 
mode of action consideration specific to chloroform, it does not affect 
the MCLGs of other trihalomethanes.
    c. Summary of major comments. EPA received many comments in support 
of the proposed MCLG calculation for chloroform, although some 
commenters disagreed with a non-zero MCLG.
    At this time, based on an analysis of all the available scientific 
data on chloroform, EPA concludes that chloroform is likely to be 
carcinogenic to humans only under high exposure conditions that lead to 
cytotoxicity and regenerative hyperplasia and that chloroform is not 
likely to be carcinogenic to humans under conditions that do not cause 
cytotoxicity and cell regeneration (USEPA 2001a). Therefore, the dose-
response is nonlinear, and the MCLG is set at 0.07 mg/L. This 
conclusion has been reviewed by the SAB (USEPA 2000d), who agree that 
nonlinear approach is most appropriate for the risk assessment of 
chloroform; it also remains consistent with the principles of the 1999 
EPA Proposed Guidelines for Carcinogenic Risk Assessment (USEPA 1999a) 
and the final Cancer Guidelines ( USEPA 2005i), which allow for 
nonlinear extrapolation.
    EPA also received some comments requesting a combined MCLG for THMs 
or HAAs. This is not appropriate because these different chemicals have 
different health effects.
2. HAA MCLGs: TCAA and MCAA
    a. Today's rule. Today's rule finalizes the proposed Stage 2 MCLG 
for TCAA of 0.02 mg/L (USEPA 2003a) and sets an MCLG for MCAA of 0.07 
mg/L. EPA is not changing the other HAA MCLGs finalized in the Stage 1 
DBPR (USEPA 1998a).
    b. Background and analysis. The Stage 1 DBPR included an MCLG for 
TCAA of 0.03 mg/L and did not include an MCLG for MCAA (USEPA 1998a). 
Based on toxicological data published after the Stage 1 DBPR, EPA 
proposed new MCLGs for TCAA and MCAA of 0.02 mg/L and 0.03 mg/L, 
respectively, in the Stage 2 proposal (USEPA 2003a). The proposed TCAA 
MCLG and its supporting analysis is being finalized unchanged in 
today's final rule. The MCLG calculation for MCAA is revised in this 
final rule, based on a new reference dose, as discussed later. See the 
proposed Stage 2 DBPR (USEPA 2003a) for a detailed discussion of the 
calculation of the MCLGs.
    TCAA. The MCLG for TCAA was calculated based on the RfD of 0.03 mg/
kg/day using a 70 kg adult body weight, a 2 L/day drinking water 
intake, and a relative source contribution of 20%. An additional 
tenfold risk management factor has been applied to account for the 
possible carcinogenicity of TCAA. This approach is consistent with EPA 
policy. TCAA induces liver tumors in mice (Ferreira-Gonzalez et al. 
1995; Pereira 1996; Pereira and Phelps 1996; Tao et al. 1996; 
Latendresse and Pereira 1997; Pereira et al. 1997) but not in rats 
(DeAngelo et al. 1997). Much of the recent data on the carcinogenicity 
of TCAA have focused on examining the carcinogenic mode(s) of action. 
However, at this time, neither the bioassay nor the mechanistic data 
are sufficient to support the development of a slope factor from which 
to quantify the cancer risk.
[GRAPHIC] [TIFF OMITTED] TR04JA06.000

    The chronic bioassay for TCAA by DeAngelo et al. (1997) was 
selected as the critical study for the development of the RfD. In this 
chronic drinking water study, a dose-response was noted for several 
endpoints and both a LOAEL and NOAEL were determined. The data are 
consistent with the findings in both the Pereira (1996) chronic 
drinking water study and the Mather et al. (1990) subchronic drinking 
water study. The RfD of 0.03 mg/kg/day is based on the NOAEL of 32.5 
mg/kg/day for liver histopathological changes in rats (DeAngelo et al. 
1997). A composite uncertainty factor of 1000 was applied in the RfD 
determination. A default uncertainty factor of 10 was applied to

[[Page 408]]

the RfD to account for extrapolation from an animal study because data 
to quantify rat-to-human differences in toxicokinetics or 
toxicodynamics are not available. The default uncertainty factor of 10 
was used to account for human variability in the absence of data on 
differences in human susceptibility. Although subchronic and chronic 
studies of TCAA have been reported for multiple species, many studies 
have focused on liver lesions and a full evaluation of a wide range of 
potential target organs has not been conducted in two different 
species. In addition, there has been no multi-generation study of 
reproductive toxicity and the data from teratology studies in rats 
provide LOAEL values but no NOAEL for developmental toxicity. Thus, an 
additional uncertainty factor of 10 was used to account for database 
insufficiencies.
    The MCLG calculation also includes a relative source contribution 
(RSC) of 20%. The RSC was derived consistent with Office of Water's 
current approach for deriving RSC. In addition to disinfected water, 
foods are expected to contribute to daily exposure to TCAA (Raymer et 
al. 2001, 2004; Reimann et al. 1996). Some of the TCAA in foods comes 
from cleaning and cooking foods in chlorinated water. Additional TCAA 
is found in some foods because of the widespread use of chlorine as a 
sanitizing agent in the food industry (USFDA 1994). EPA was not able to 
identify any dietary surveys or duplicate diet studies of TCAA in the 
diet. TCAA also has been identified in rain water, suggesting some 
presence in the atmosphere (Reimann et al. 1996); however, due to the 
low volatility (0.5--0.7 mm Hg at 25 [deg]C) of TCAA, exposure from 
ambient air is expected to be minimal. Dermal exposure to disinfected 
water is also unlikely to be significant. A study by Xu et al. (2002) 
reports that dermal exposure from bathing and showering is only 0.01% 
of that from oral exposure. In addition, the solvents 
trichloroethylene, tetrachlorethylene, 1,1,1-trichloroethane (often 
found in ambient air and drinking water), and the disinfection 
byproduct chloral hydrate all contribute to the body's TCAA load since 
each of these compounds is metabolized to TCAA (ATSDR 2004; ATSDR 
1997a; ATSDR 1997b; USEPA 2000e). Due to the limitations primarily in 
the dietary data and a clear indication of exposure from other sources, 
EPA applied a relative source contribution of 20%.
    MCAA. The MCLG for MCAA uses the following calculations: An RfD of 
0.01 mg/kg/day, a 70 kg adult consuming 2 L/day of tap water, and a 
relative source contribution of 20%.
    The RfD included in the proposal was based on a chronic drinking 
water study in rats conducted by DeAngelo et al. (1997). In the 
assessment presented for the proposed rule, the LOAEL from this study 
was identified as 3.5 mg/kg/day based on increased absolute and 
relative spleen weight in the absence of histopathologic changes. After 
reviewing comments and further analysis of the data, EPA concludes that 
it is more appropriate to identify this change as a NOAEL. Increased 
spleen weights in the absence of histopathological effects are not 
necessarily adverse. In addition, spleen weights were decreased, rather 
than increased in the mid- and high-dose groups in the DeAngelo et al. 
(1997) study and were accompanied by a significant decrease in body 
weight, decreased relative and absolute liver weights, decreased 
absolute kidney weight, and an increase in relative testes weight. 
Accordingly, the mid-dose in this same study (26.1 mg/kg/day) has been 
categorized as the LOAEL with the lower 3.5 mg/kg/day dose as a NOAEL.
    Based on a NOAEL of 3.5 mg/kg/day (DeAngelo et al. 1997), the 
revised RfD was calculated as shown below, with a composite uncertainty 
factor of 300. EPA used a default uncertainty factor of 10 to account 
for extrapolation from an animal study, since no data on rat-to-human 
differences in toxicokinetics or toxicodynamics were identified. A 
default uncertainty factor of 10 was used to account for human 
variability in the absence of data on the variability in the 
toxicokinetics of MCAA in humans or in human susceptibility to MCAA. An 
additional uncertainty factor of three was used to account for database 
insufficiencies. Although there is no multi-generation reproduction 
study, the available studies of reproductive and developmental 
processes suggest that developmental toxicity is unlikely to be the 
most sensitive endpoint. This led to the following calculation of the 
Reference Dose (RfD) and MCLG for MCAA:
[GRAPHIC] [TIFF OMITTED] TR04JA06.001

Where:

3.5 mg/kg/day = NOAEL for decreased body weight plus decreased liver, 
kidney and spleen weights in rats exposed to MCA for 104 weeks in 
drinking water (DeAngelo et al. 1997).
300 = composite uncertainty factor chosen to account for inter species 
extrapolation, inter-individual variability in humans, and deficiencies 
in the database.
[GRAPHIC] [TIFF OMITTED] TR04JA06.002

    The RSC for MCAA was selected using comparable data to that 
discussed for TCAA. MCAA, like TCAA, has been found in foods and is 
taken up by foods during cooking (15% in chicken to 62% in pinto beans) 
and cleaning (2.5% for lettuce) with water containing 500 ppb MCAA 
(Reimann et al.1996; Raymer et al. 2001, 2004). Rinsing of cooked foods 
did not increase the MCAA content of foods to the same extent as was 
observed for TCAA (Raymer et al. 2004). MCAA was found to be completely 
stable in water boiled for 60 minutes and is likely to be found in the 
diet due to the use of chlorinated water in food preparation and the 
use of chlorine as a sanitizing agent by the food industry (USFDA 
1994). As with TCAA, inhalation and dermal exposures are unlikely to be 
significant. Dermal exposure from bathing and showering was estimated 
to contribute only 0.03% of that from oral exposure (Xu et al. 2002). 
As with TCAA, due to the limitations in dietary data and a clear 
indication of exposure from other

[[Page 409]]

sources, EPA applied a relative source contribution of 20%.
    c. Summary of major comments. EPA received few comments on MCAA and 
TCAA. The majority of comments about the MCLGs for TCAA and MCAA were 
general MCLG questions, including RSC derivation. Some commenters 
questioned why MCAA, TCAA, and chloroform were calculated using an RSC 
of 20%. In particular, some commenters compared these calculations to 
that for DBCM in the Stage 1 DBPR, which uses 80%. Each of the MCLGs 
set for chloroform, TCAA, and MCAA under this rule is calculated using 
the best available science and EPA Office of Water's current approach 
for deriving the RSC. EPA chose an RSC of 20%, not 80%, because of 
clear indications of exposure from other sources; data limitations 
preclude the derivation of a specific RSC.
    The RSC for DBCM was 80% in the Stage 1 DBPR. The DBCM MCLG is not 
part of today's rulemaking. Any possible future revision to the DBCM 
MCLG as a result of an RSC change would not affect the MCL for TTHM 
finalized in today's rule.
    In response to comments received on the RfD for MCAA, EPA has 
reviewed the critical study regarding the appropriateness of an 
increase in spleen weight in the absence of histopathology as a LOAEL. 
EPA has determined that the dose associated with this endpoint is more 
appropriately categorized as a NOAEL rather than a LOAEL and has 
revised the RfD and MCLG for MCAA.

B. Consecutive Systems

    Today's rule includes provisions for consecutive systems, which are 
public water systems that receive some or all of their finished water 
from another water system (a wholesale system). Consecutive systems 
face particular challenges in providing water that meets regulatory 
standards for DBPs and other contaminants whose concentration can 
increase in the distribution system. Moreover, previous regulation of 
DBP levels in consecutive systems varies widely among States. In 
consideration of these factors, EPA is finalizing monitoring, 
compliance schedule, and other requirements specifically for 
consecutive systems. These requirements are intended to facilitate 
compliance by consecutive systems with MCLs for TTHM and HAA5 under the 
Stage 2 DBPR and help to ensure that consumers in consecutive systems 
receive equivalent public health protection.
1. Today's Rule
    As public water systems, consecutive systems must provide water 
that meets the MCLs for TTHM and HAA5 under the Stage 2 DBPR, use 
specified analytical methods, and carry out associated monitoring, 
reporting, recordkeeping, public notification, and other requirements. 
The following discusses a series of definitions needed for addressing 
consecutive system requirements in today's rule. Later sections of this 
preamble provide further details on how rule requirements (e.g., 
schedule and monitoring) apply to consecutive systems.
    A consecutive system is a public water system that receives some or 
all of its finished water from one or more wholesale systems.
    Finished water is water that has been introduced into the 
distribution system of a public water system and is intended for 
distribution and consumption without further treatment, except as 
necessary to maintain water quality in the distribution system (e.g., 
booster disinfection, addition of corrosion control chemicals).
    A wholesale system is a public water system that treats source 
water as necessary to produce finished water and then delivers finished 
water to another public water system. Delivery may be through a direct 
connection or through the distribution system of one or more 
consecutive systems.
    The combined distribution system is defined as the interconnected 
distribution system consisting of the distribution systems of wholesale 
systems and of the consecutive systems that receive finished water from 
those wholesale system(s).
    EPA is allowing States some flexibility in defining what systems 
are a part of a combined distribution system. This provision determines 
effective dates for requirements in today's rule; see Section IV.E 
(Compliance Schedules) for further discussion. EPA has consulted with 
States and deferred to their expertise regarding the nature of the 
connection in making combined distribution system determinations. In 
the absence of input from the State, EPA will determine that combined 
distribution systems include all interconnected systems for the purpose 
of determining compliance schedules for implementation of this rule.
2. Background and Analysis
    The practice of public water systems buying and selling water to 
each other has been commonplace for many years. Reasons include saving 
money on pumping, treatment, equipment, and personnel; assuring an 
adequate supply during peak demand periods; acquiring emergency 
supplies; selling surplus supplies; and delivering a better product to 
consumers. EPA estimates that there are more than 10,000 consecutive 
systems nationally.
    Consecutive systems face particular challenges in providing water 
that meets regulatory standards for contaminants that can increase in 
the distribution system. Examples of such contaminants include 
coliforms, which can grow if favorable conditions exist, and some DBPs, 
including THMs and HAAs, which can increase when a disinfectant and DBP 
precursors continue to react in the distribution system.
    EPA included requirements specifically for consecutive systems 
because States have taken widely varying approaches to regulating DBPs 
in consecutive systems in previous rules. For example, some States have 
not regulated DBP levels in consecutive systems that deliver 
disinfected water but do not add a disinfectant. Other States have 
determined compliance with DBP standards based on the combined 
distribution system that includes both the wholesaler and consecutive 
systems. In this case, sites in consecutive systems are treated as 
monitoring sites within the combined distribution system. Neither of 
these approaches provide the same level of public health protection as 
non-consecutive systems receive under the Stage 1 DBPR. Once fully 
implemented, today's rule will ensure similar protection for consumers 
in consecutive systems.
    In developing its recommendations, the Stage 2 M-DBP Advisory 
Committee recognized two principles related to consecutive systems: (1) 
consumers in consecutive systems should be just as well protected as 
customers of all systems, and (2) monitoring provisions should be 
tailored to meet the first principle. Accordingly, the Advisory 
Committee recommended that all wholesale and consecutive systems comply 
with provisions of the Stage 2 DBPR on the same schedule required of 
the wholesale or consecutive system serving the largest population in 
the combined distribution system. In addition, the Advisory Committee 
recommended that EPA solicit comments on issues related to consecutive 
systems that the Advisory Committee had not fully explored (USEPA 
2000a). EPA agreed with these recommendations and they are reflected in 
today's rule.

[[Page 410]]

3. Summary of Major Comments
    Commenters generally supported the proposed definitions. However, 
commenters did express some concerns, especially with including a time 
period of water delivery that defined whether a system was a 
consecutive system (proposed to trigger plant-based monitoring 
requirements) or wholesale system (proposed to allow determination that 
a combined distribution system existed). EPA has dropped this 
requirement from the final rule; population-based monitoring 
requirements in the final rule do not need to define how long a plant 
must operate in order to be considered a plant, and EPA has provided 
some flexibility for States to determine which systems comprise a 
combined distribution system (without presenting a time criterion).
    Other commenters expressed concern that the proposed definition of 
consecutive system was inconsistent with use of the term prior to the 
rulemaking. EPA acknowledges that the Agency has not previously 
formally defined the term, but believes that the definition in today's 
rule best considers all commenters' concerns, while also providing for 
accountability and public health protection in as simple a manner as is 
possible given the many consecutive system scenarios that currently 
exist.
    Several States requested flexibility to determine which systems 
comprised a combined distribution system under this rule; EPA has 
included that flexibility for situations in which systems have only a 
marginal association (such as an infrequently used emergency 
connection) with other systems in the combined distribution system. To 
prepare for the IDSE and subsequent Stage 2 implementation, EPA has 
worked with States in identifying all systems that are part of each 
combined distribution system.
    Finally, several commenters requested that the wholesale system 
definition replace ``public water system'' with ``water system'' so 
that wholesale systems serving fewer than 25 people would not be 
considered public water systems. EPA did not change the definition in 
today's rule; EPA considers any water system to be a public water 
system (PWS) if it serves 25 or more people either directly (retail) or 
indirectly (by providing finished water to a consecutive system) or 
through a combination of retail and consecutive system customers. If a 
PWS receives water from an unregulated entity, that PWS must meet all 
compliance requirements (including monitoring and treatment techniques) 
that any other public water system that uses source water of unknown 
quality must meet.

C. LRAA MCLs for TTHM and HAA5

1. Today's Rule
    This rule requires the use of locational running annual averages 
(LRAAs) to determine compliance with the Stage 2 MCLs of 0.080 mg/L 
TTHM and 0.060 mg/L HAA5. All systems, including consecutive systems, 
must comply with the MCLs for TTHM and HAA5 using sampling sites 
identified under the Initial Distribution System Evaluation (IDSE) or 
using existing Stage 1 DBPR compliance monitoring locations (as 
discussed in Section IV.F). EPA has dropped the proposed phased 
approach for LRAA implementation (Stage 2A and Stage 2B) by removing 
Stage 2A and redesignating Stage 2B as Stage 2.
    Details of monitoring requirements and compliance schedules are 
discussed in preamble Sections IV.G and IV.E, respectively, and may be 
found in subpart V of today's rule.
2. Background and Analysis
    The MCLs for TTHM and HAA5 are the same as those proposed, 0.080 
mg/L TTHM and 0.060 mg/L HAA5 as an LRAA. See the proposed rule (68 FR 
49584, August 18, 2003) (USEPA 2003a) for a more detailed discussion of 
the analysis supporting the MCLs. The primary objective of the LRAA is 
to reduce exposure to high DBP levels. For an LRAA, an annual average 
must be computed at each monitoring location. The RAA compliance basis 
of the 1979 TTHM rule and the Stage 1 DBPR allows a system-wide annual 
average under which high DBP concentrations in one or more locations 
are averaged with, and dampened by, lower concentrations elsewhere in 
the distribution system. Figure IV.C-1 illustrates the difference in 
calculating compliance with the MCLs for TTHM between a Stage 1 DBPR 
RAA, and the Stage 2 DBPR LRAA.
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    EPA and the Stage 2 M-DBP Advisory Committee considered an array of 
alternative MCL strategies. The Advisory Committee discussions 
primarily focused on the relative magnitude of exposure reduction 
versus the expected impact on the water industry and its customers. 
Strategies considered included across the board requirements, such as 
significantly decreasing the MCLs (e.g., 40/30) or single hit MCLs 
(e.g., all samples must be below 80/60); and risk targeting 
requirements. In the process of evaluating alternatives, EPA and the 
Advisory Committee reviewed vast quantities of data and many analyses 
that addressed health effects, DBP occurrence, predicted reductions in 
DBP levels, predicted technology changes,

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and capital, annual, and household costs. The Advisory Committee 
recommended and EPA proposed the risk targeting approach of 80/60 as an 
LRAA preceded by an IDSE. Today's rule finalizes these requirements.
    EPA has chosen compliance based on an LRAA due to concerns about 
levels of DBPs above the MCL in some portions of the distribution 
system. The LRAA standard will eliminate system-wide averaging of 
monitoring results from different monitoring locations. The individuals 
served in areas of the distribution system with above average DBP 
occurrence levels masked by averaging under an RAA are not receiving 
the same level of health protection. Although an LRAA standard still 
allows averaging at a single location over an annual period, EPA 
concluded that changing the basis of compliance from an RAA to an LRAA 
will result in decreased exposure to higher DBP levels (see Section VI 
for predictions of DBP reductions under the LRAA MCLs). This conclusion 
is based on three considerations:
    (1) There is considerable evidence that under the current RAA MCL 
compliance monitoring requirements, a small but significant proportion 
of monitoring locations experience high DBP levels at least some of the 
time. Of systems that collected data under the Information Collection 
Rule that met the Stage 1 DBPR RAA MCLs, 14 percent had TTHM single 
sample concentrations greater than the Stage 1 MCL, and 21 percent had 
HAA5 single sample concentrations above the MCL. Although most TTHM and 
HAA5 samples were below 100 [mu]g/L, some ranged up to 140 [mu]g/L and 
130 [mu]g/L, respectively.
    (2) In some situations, the populations served by certain portions 
of the distribution system consistently receive water that exceeds 
0.080 mg/L for TTHM or 0.060 mg/L for HAA5 (both as LRAAs) even though 
the system is in compliance with Stage 1 MCLs). Of Information 
Collection Rule systems meeting the Stage 1 DBPR MCLs as RAAs, five 
percent had monitoring locations that exceeded 0.080 mg/L TTHM and 
three percent exceeded 0.060 mg/L HAA5 as an annual average (i.e., as 
LRAAs) by up to 25% (calculated as indicated in Figure IV.C-1). 
Customers served at these locations consistently received water with 
TTHM and/or HAA5 concentrations higher than the system-wide average and 
higher than the MCL.
    (3) Compliance based on an LRAA will remove the opportunity for 
systems to average out samples from high and low quality water sources. 
Some systems are able to comply with an RAA MCL even if they have a 
plant with a poor quality water source (that thus produces high 
concentrations of DBPs) because they have another plant that has a 
better quality water source (and thus lower concentrations of DBPs). 
Individuals served by the plant with the poor quality source will 
usually have higher DBP exposure than individuals served by the other 
plant.
    In part, both the TTHM and HAA5 classes are regulated because they 
occur at high levels and represent chlorination byproducts that are 
produced from source waters with a wide range of water quality. The 
combination of TTHM and HAA5 represent a wide variety of compounds 
resulting from bromine substitution and chlorine substitution reactions 
(e.g., bromoform has three bromines, TCAA has three chlorines, BDCM has 
one bromine and two chlorines). EPA believes that the TTHM and HAA5 
classes serve as an indicator for unidentified and unregulated DBPs. 
EPA believes that controlling the occurrence levels of TTHM and HAA5 
will help control the overall levels of chlorination DBPs.
3. Summary of Major Comments
    Commenters supported the proposed, risk-targeted MCL strategy over 
the alternative MCL strategies that were considered by the Advisory 
Committee as the preferred regulatory strategy. Commenters concurred 
with EPA's analysis that such an approach will reduce peak and average 
DBP levels. Commenters supported the Stage 2 long-term MCLs of 0.080 
mg/L TTHM and 0.060 mg/L HAA5 as LRAAs.
    EPA received many comments on today's MCLs specific to consecutive 
systems. While commenters supported consecutive system compliance with 
the Stage 2 DBPR in order to provide comparable levels of public health 
protection, they noted that it would be difficult for many consecutive 
systems to meet Stage 2 requirements because they have not had to meet 
the full scope of DBP requirements under previous rules. EPA has 
developed a training and outreach program to assist these systems and 
encourages States, wholesale systems, and professional associations to 
also provide assistance.
    Some commenters expressed concern about holding consecutive systems 
responsible for water quality over which they have no control. Several 
commenters were concerned about the establishment of contracts between 
wholesale and consecutive systems, including concern about a strain on 
their relationship, wholesale system reluctance to commit to keep DBPs 
at a level suggested by the consecutive systems, and the time and money 
it could take to work out differences. Although setting up a contract 
is a prudent business action, commenters noted that small consecutive 
water systems have few resources to sue for damages should the 
wholesaler provide water exceeding the MCL.
    The purpose of DBPRs is to protect public health from exposure to 
high DBP levels. Not requiring violations when distributed water 
exceeds MCLs undermines the intent of the rule. While EPA recognizes 
consecutive systems do not have full control over the water they 
receive, agreements between wholesale and consecutive systems may 
specify water quality and actions required of the wholesaler if those 
water quality standards are not met.
    Finally, commenters recommended that the Stage 2A provisions in the 
proposed rule be removed. These provisions (compliance with locational 
running annual average MCLs of 0.120 mg/L for TTHM and 0.100 mg/L for 
HAA5) required systems to comply with the Stage 1 MCLs (as running 
annual averages) and the Stage 2A MCLs (as LRAAs) concurrently until 
systems were required to comply with Stage 2B MCLs. Commenters noted 
that having two separate MCLs for an individual system to comply with 
at the same time was confusing to the system and its customers. In 
addition, State resources needed for compliance determinations and data 
management for this short-term requirement would be resource-intensive. 
Finally, resources spent to comply with Stage 2A would be better spent 
in complying with Stage 2B, especially given that some of the changes 
for Stage 2A compliance might not provide any benefit for Stage 2B. 
Since EPA agrees with commenters' concerns, the Stage 2A requirements 
have been removed from the final rule.

D. BAT for TTHM and HAA5

1. Today's Rule
    Today, EPA is identifying the best available technology (BAT) for 
the TTHM and HAA5 LRAA MCLs (0.080 mg/L and 0.060 mg/L respectively) 
for systems that treat their own source water as one of the three 
following technologies:
    (1) GAC10 (granular activated carbon filter beds with an empty-bed 
contact time of 10 minutes based on average daily flow and a carbon 
reactivation frequency of every 120 days)
    (2) GAC20 (granular activated carbon filter beds with an empty-bed 
contact time of 20 minutes based on average

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daily flow and a carbon reactivation frequency of every 240 days)
    (3) Nanofiltration (NF) using a membrane with a molecular weight 
cutoff of 1000 Daltons or less.
    EPA is specifying a different BAT for consecutive systems than for 
systems that treat their own source water to meet the TTHM and HAA5 
LRAA MCLs. The consecutive system BAT is chloramination with management 
of hydraulic flow and storage to minimize residence time in the 
distribution system for systems that serve at least 10,000 people and 
management of hydraulic flow and storage to minimize residence time in 
the distribution system for systems that serve fewer than 10,000 
people.
2. Background and Analysis
    The BATs are the same as was proposed, except that consecutive 
systems serving fewer than 10,000 people do not have chloramination as 
part of the consecutive system BAT. See the proposal (68 FR 49588, 
August 18, 2003) (USEPA 2003a) for more detail on the analysis 
supporting these requirements. The Safe Drinking Water Act directs EPA 
to specify BAT for use in achieving compliance with the MCL. Systems 
unable to meet the MCL after application of BAT can get a variance (see 
Section IV.K for a discussion of variances). Systems are not required 
to use BAT in order to comply with the MCL. PWSs may use any State-
approved technologies as long as they meet all drinking water 
standards.
    EPA examined BAT options first by analyzing data from the 
Information Collection Rule treatment studies designed to evaluate the 
ability of GAC and NF to remove DBP precursors. Based on the treatment 
study results, GAC is effective for controlling DBP formation for 
waters with influent TOC concentrations below approximately 6 mg/L 
(based on the Information Collection Rule and NRWA data, over 90 
percent of plants have average influent TOC levels below 6 mg/L (USEPA 
2003c)). Of the plants that conducted an Information Collection Rule 
GAC treatment study, approximately 70 percent of the surface water 
plants studied could meet the 0.080 mg/L TTHM and 0.060 mg/L HAA5 MCLs, 
with a 20 percent safety factor (i.e., 0.064 mg/L and 0.048 mg/L, 
respectively) using GAC with 10 minutes of empty bed contact time and a 
120 day reactivation frequency, and 78 percent of the plants could meet 
the MCLs with a 20 percent safety factor using GAC with 20 minutes of 
empty bed contact time and a 240 day reactivation frequency. Because 
the treatment studies were conducted at plants with much poorer water 
quality than the national average, EPA believes that much higher 
percentages of plants nationwide could meet the MCLs with the proposed 
GAC BATs.
    Among plants using GAC, larger systems would likely realize an 
economic benefit from on-site reactivation, which could allow them to 
use smaller, 10-minute empty bed contact time contactors with more 
frequent reactivation (i.e., 120 days or less). Most small systems 
would not find it economically advantageous to install on-site carbon 
reactivation facilities, and thus would opt for larger, 20-minute empty 
bed contact time contactors, with less frequent carbon replacement 
(i.e., 240 days or less).
    The Information Collection Rule treatment study results also 
demonstrated that nanofiltration was the better DBP control technology 
for ground water sources with high TOC concentrations (i.e., above 
approximately 6 mg/L). The results of the membrane treatment studies 
showed that all ground water plants could meet the 0.080 mg/L TTHM and 
0.060 mg/L HAA5 MCLs, with a 20% safety factor (i.e., 0.064 mg/L and 
0.048 mg/L, respectively) at the system average distribution system 
residence time using nanofiltration. Nanofiltration would be less 
expensive than GAC for high TOC ground waters, which generally require 
minimal pretreatment prior to the membrane process. Also, 
nanofiltration is an accepted technology for treatment of high TOC 
ground waters in Florida and parts of the Southwest, areas of the 
country with elevated TOC levels in ground waters.
    The second method that EPA used to examine alternatives for BAT was 
the Surface Water Analytical Tool model that was developed to compare 
alternative regulatory strategies as part of the Stage 1 and Stage 2 M-
DBP Advisory Committee deliberations. EPA modeled a number of BAT 
options. In the model, GAC10 was defined as granular activated carbon 
with an empty bed contact time of 10 minutes and a reactivation or 
replacement interval of 90 days or longer. GAC20 was defined as 
granular activated carbon with an empty bed contact time of 20 minutes 
and a reactivation or replacement interval of 90 days or longer.
    The compliance percentages forecasted by the SWAT model are 
indicated in Table IV.D-1. EPA estimates that more than 97 percent of 
large systems will be able to achieve the Stage 2 MCLs with the GAC 
BAT, regardless of post-disinfection choice (Seidel Memo, 2001). 
Because the source water quality (e.g., DBP precursor levels) in medium 
and small systems is expected to be comparable to or better than that 
for the large system (USEPA 2005f), EPA believes it is conservative to 
assume that at least 90 percent of medium and small systems will be 
able to achieve the Stage 2 MCLs if they were to apply one of the 
proposed GAC BATs. EPA assumes that small systems may adopt GAC20 in a 
replacement mode (with replacement every 240 days) over GAC10 because 
it may not be economically feasible for some small systems to install 
and operate an on-site GAC reactivation facility. Moreover, some small 
systems may find nanofiltration cheaper than the GAC20 in a replacement 
mode if their specific geographic locations cause a relatively high 
cost for routine GAC shipment.

 Table IV.D-1.--SWAT Model Predictions of Percent of Large Plants in Compliance With TTHM and HAA5 Stage 2 MCLs After Application of Specified Treatment
                                                                      Technologies
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          Compliance with 0.080 mg/L TTHM and 0.060 mg/L  Compliance with 0.064 mg/L TTHM and 0.048 mg/L
                                                                            HAA5 LRAAs                       HAA5 LRAAs (MCLs with 20% Safety factor)
                                                         -----------------------------------------------------------------------------------------------
                       Technology                              Residual disinfectant                          Residual  disinfectant
                                                         --------------------------------   All systems  --------------------------------   All systems
                                                             Chlorine       Chloramine       (percent)       Chlorine       Chloramine       (percent)
                                                             (percent)       (percent)                       (percent)       (percent)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Enhanced Coagulation (EC)...............................            73.5            76.9            74.8            57.2            65.4            60.4
EC (no pre-disinfection)................................            73.4            88.0            78.4            44.1            62.7            50.5
EC & GAC10..............................................             100            97.1            99.1             100            95.7            98.6

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EC & GAC20..............................................             100             100             100             100             100             100
EC & All Chloramines....................................              NA            83.9              NA              NA            73.6             NA
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Enhanced coagulation/softening is required under the Stage 1 DBPR for conventional plants.
Source: Seidel (2001).

    The BAT requirements for large consecutive systems are the same as 
proposed, but the requirements have changed for small consecutive 
systems. EPA believes that the best compliance strategy for consecutive 
systems is to collaborate with wholesalers on the water quality they 
need. For consecutive systems that are having difficulty meeting the 
MCLs, EPA is specifying a BAT of chloramination with management of 
hydraulic flow and storage to minimize residence time in the 
distribution system for systems serving at least 10,000 and management 
of hydraulic flow and storage to minimize residence time in the 
distribution system for systems serving fewer than 10,000. EPA believes 
that small consecutive systems can use this BAT to comply with the 
Stage 2 DBPR, but if they cannot, then they can apply to the State for 
a variance.
    Chloramination has been used for residual disinfection for many 
years to minimize the formation of chlorination DBPs, including TTHM 
and HAA5 (USEPA 2003d). EPA estimates that over 50 percent of large 
subpart H systems serving at least 10,000 use chloramination for Stage 
1. The BAT provision to manage hydraulic flow and minimize residence 
time in the distribution system is to facilitate the maintenance of the 
chloramine residual and minimize the likelihood for nitrification. EPA 
has not included chloramination for consecutive systems as part of the 
BAT for systems serving fewer than 10,000 due to concerns about their 
ability to properly control the process, given that many have no 
treatment capability or expertise and the Agency's concern about such 
systems having operational difficulties such as distribution system 
nitrification.
    EPA believes that the BATs for nonconsecutive systems are not 
appropriate for consecutive systems because their efficacy in 
controlling DBPs is based on precursor removal. Consecutive systems 
face the unique challenge of receiving waters in which DBPs are already 
present if the wholesale system has used a residual disinfectant, which 
the BATs for non-consecutive systems do not effectively remove. GAC is 
not cost-effective for removing DBPs. Nanofiltration is only moderately 
effective at removing THMs or HAAs if membranes with a very low 
molecular weight cutoff (and very high cost of operation are employed). 
Therefore, GAC and nanofiltration are not appropriate BATs for 
consecutive systems.
3. Summary of Major Comments
    Commenters concurred with EPA's identification of BATs for non-
consecutive systems but expressed concern about the BAT for consecutive 
systems. Many commenters agreed that Stage 2 compliance for consecutive 
systems would usually best be achieved by improved treatment by the 
wholesale system. However, they noted that the proposed BAT may not be 
practical for compliance if water delivered to the consecutive system 
is at or near DBP MCLs. In addition, chloramination requires operator 
supervision and adjustment and many consecutive systems that buy water 
may be reluctant to operate chemical feed systems. Therefore, EPA 
included chloramines as part of the BAT in today's rule only for 
systems serving at least 10,000 because of the operator attention it 
requires and concerns with safety and nitrification. While some 
commenters believed that having a BAT for consecutive systems 
contradicts the premise of the Stage 1 DBPR that DBPs are best 
controlled through TOC removal and optimizing disinfection processes, 
the SDWA requires EPA to identify a BAT for all systems required to 
meet an MCL. No commenter recommended an alternative BAT. EPA still 
believes that precursor removal remains a highly effective strategy to 
reduce DBPs. Thus, EPA encourages States to work with wholesale systems 
and consecutive systems to identify strategies to ensure compliance, 
especially those systems with DBP levels close to the MCL.

E. Compliance Schedules

1. Today's Rule
    This section specifies compliance dates for the IDSE and MCL 
compliance requirements in today's rule. As described elsewhere in 
Section IV of this preamble, today's rule requires PWSs to carry out 
the following activities:
     Conduct initial distribution system evaluations (IDSEs) on 
a required schedule. Systems may comply by using any of four approaches 
for which they qualify (standard monitoring, system specific study, 40/
30 certification, or very small system waiver).
     Determine Stage 2 monitoring locations based on the IDSE.
     Comply with Stage 2 MCLs on a required schedule.
    Compliance dates for these activities vary by PWS size. Table IV.E-
1 and Figure IV.E-1 specify IDSE and Stage 2 compliance dates. 
Consecutive systems of any size must comply with the requirements of 
the Stage 2 DBPR on the same schedule as required for the largest 
system in the combined distribution system.

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                                                    Table IV.E-1.--IDSE and Stage 2 Compliance Dates
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Compliance dates by PWS size (retail population served) \1\
                                    --------------------------------------------------------------------------------------------------------------------
            Requirement                 CWSs and NTNCWSs
                                        serving at least        CWSs and NTNCWSs        CWSs and NTNCWSs     CWSs serving <10,000     NTNCWSs serving
                                             100,000          serving 50,000-99,999  serving 10,000-49,999                                <10,000
--------------------------------------------------------------------------------------------------------------------------------------------------------
Submit IDSE monitoring plan OR.....  October 1, 2006.......  April 1, 2007.........  October 1, 2007......  April 1, 2008........  Not applicable.
Submit IDSE system specific study
 plan OR.
Submit 40/30 certification OR......
Receive very small system waiver
 from State.
Complete standard monitoring or      September 30, 2008....  March 31, 2009........  September 30, 2009...  March 31, 2010.......  Not applicable.
 system specific study.
Submit IDSE Report.................  January 1, 2009.......  July 1, 2009..........  January 1, 2010......  July 1, 2010.........  Not applicable.
Begin subpart V (Stage 2)            April 1, 2012.........  October 1, 2012.......  October 1, 2013......  October 1, 2013
 compliance monitoring \2\.                                                                                  (October 1, 2014 if
                                                                                                             Crypto- sporidium
                                                                                                             monitoring is
                                                                                                             required under
                                                                                                             Subpart W)..
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Wholesale and consecutive systems that are part of a combined distribution system must comply based on the schedule required of the largest system
  in the combined distribution system.
\2\ States may grant up to an additional 2 years for systems making capital improvements.

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2. Background and Analysis
    The compliance schedule in today's final rule stems from the risk-
targeted approach of the rule, wherein PWSs conduct initial monitoring 
to determine locations and concentrations of high DBPs. A primary 
objective of this schedule is to ensure that PWSs identify locations 
with high DBP concentrations and provide appropriate additional 
treatment in a timely manner for high risk areas, while not requiring 
low risk systems to add additional treatment. The compliance schedule 
balances the objective of early risk-targeted monitoring with adequate 
time for PWSs and the State or primacy agency to assure full 
implementation and compliance. EPA is establishing concurrent 
compliance schedules under the Stage 2 DBPR for all systems (both 
wholesale systems and consecutive systems) in a particular combined 
distribution system because this will assure comparable risk-based 
targeting information being available at the same time for all PWSs 
that are part of a combined distribution system and thereby allow for 
more cost-effective compliance with TTHM and HAA5 MCLs.
    SDWA section 1412(b)(10) states that a drinking water regulation 
shall take effect 3 years from the promulgation date unless the 
Administrator determines that an earlier date is practicable. Today's 
rule requires PWSs to begin monitoring prior to 3 years from the 
promulgation date. Based on EPA's assessment and recommendations of the 
Advisory Committee, as described in this section, EPA has determined 
that these monitoring start dates are practicable and appropriate.
    Systems must submit their IDSE plans (monitoring plans for standard 
monitoring, study plans for system specific studies) to the primacy 
agency for review and approval. The State or primacy agency will then 
have 12 months to review, and, as necessary, consult with the system. A 
number of PWSs will then conduct one year of distribution system 
monitoring for TTHM and HAA5 at locations other than those currently 
used for Stage 1 DBPR compliance monitoring. At the conclusion of this 
monitoring, these PWSs have three months to evaluate analysis and 
monitoring results and submit Stage 2 compliance monitoring locations 
and schedules to the State or primacy agency. Where required, PWSs must 
provide the necessary level of treatment to comply with the Stage 2 
MCLs within three years of the completion of State or primacy agency 
review of the IDSE report, though States may allow an additional two 
years for PWSs making capital improvements.
    EPA has modified the proposed compliance schedule to stagger 
monitoring start dates for PWSs serving 10,000 to 99,999 people and to 
allow more time for development and review of IDSE monitoring plans 
prior to the start of monitoring. The following discussion addresses 
these changes from the proposal.
    The proposed rule required all PWSs serving at least 10,000 people 
(plus smaller systems that are part of a combined distribution system 
with a PWS that serves at least 10,000 people) to complete IDSE 
monitoring and submit IDSE reports (including recommended Stage 2 
compliance monitoring locations) two years after rule promulgation, 
followed by one year for review of IDSE reports, after which systems 
had three years to come into compliance with Stage 2B MCLs.
    Under today's final rule, PWSs serving at least 100,000 people 
(plus smaller systems that are part of the combined distribution 
system) will meet the same Stage 2 compliance deadlines as proposed. 
However, the timing of the IDSE has been changed to allow for a more 
even workload and a greater opportunity for primacy agency involvement 
(e.g., through monitoring plan review and approval). The IDSE plan 
submission dates for PWSs serving 50,000 to 99,999 people (plus smaller 
systems that are part of the combined distribution system) will be 12 
months after the effective date; for PWSs serving 10,000 to 49,999 
(plus smaller systems that are part of the combined distribution 
system), the IDSE plan submission dates will be 18 months after the 
effective date. The Stage 2 compliance schedule for systems serving 
fewer than 10,000 people remains the same as proposed. Stage 2 MCL 
compliance dates are modified accordingly.
    This staggering of IDSE start dates for PWSs serving 10,000 to 
99,999 people is advantageous in several respects:

     Provides PWSs greater assurance that IDSEs are properly 
conducted by requiring IDSE plan review prior to conducting the IDSE.
     Provides additional time to develop budgets and establish 
contracts with laboratories.
     Spreads out the workload for technical assistance and 
guidance. The staggered schedule will allow States and EPA to provide 
more support to individual PWSs as needed.
     Provides time for DBP analytical laboratories to build 
capacity as needed to accommodate the sample analysis needs of PWSs and 
extends and smooths the demand for laboratory services.
     Maintains simultaneous rule compliance with the LT2ESWTR 
as recommended by the Stage 2 M-DBP Advisory Committee and as mandated 
by the 1996 SDWA Amendments, which require that EPA ``minimize the 
overall risk of adverse health effects by balancing the risk from the 
contaminant and the risk from other contaminants the concentrations of 
which may be affected by the use of a treatment technique or process 
that would be employed to attain the maximum contaminant level'' (Sec. 
1412(b)(5)(B)(i)).

    The Advisory Committee recommended the Initial Distribution System 
Evaluation, as discussed in Section IV.F, and EPA is finalizing an IDSE 
schedule generally consistent with the Advisory Committee timeframe 
recommendation, but modified to stagger the schedule for systems 
serving more than 10,000 but less than 100,000, and to address public 
comments on the IDSE requirements.
    For all systems, the IDSE schedule has been revised to allow 
systems to submit and States or primacy agencies to review (and revise, 
if necessary) systems' recommendations for IDSE and Stage 2 monitoring 
locations, while still allowing systems three years after completion of 
the State or primacy agency review of Stage 2 compliance monitoring 
locations to make necessary treatment and operational changes to comply 
with Stage 2 MCLs.
    Figure IV.E-2 illustrates compliance schedules for examples of 
three combined distribution systems, with the schedule dictated by the 
retail population served by the largest system.

                   Figure IV.E-2.--Schedule Examples.
------------------------------------------------------------------------
 
-------------------------------------------------------------------------
--Wholesale system (pop. 64,000) with three consecutive systems (pops.
 21,000; 15,000; 5,000):
    --IDSE monitoring plan due for all systems April 1, 2007 since
     wholesale system serves 50,000-99,999
    --Stage 2 compliance beginning October 1, 2012 for all systems
--Wholesale system (pop. 4,000) with three consecutive systems (pops.
 21,000; 5,000; 5,000):

[[Page 418]]

 
    --IDSE monitoring plan due for all systems October 1, 2007 since the
     largest system in combined distribution system serves 10,000-49,999
    --Stage 2 compliance beginning October 1, 2013 for all systems
--Wholesale system (pop. 4,000) with three consecutive systems (pops.
 8,000; 5,000; 5,000):
    --IDSE monitoring plan due for all systems April 1, 2008 since no
     individual system in combined distribution system exceeds 10,000
     (even though total population exceeds 10,000)
    --Stage 2 compliance beginning October 1, 2013 if no Cryptosporidium
     monitoring under the LT2ESWTR is required or beginning October 1,
     2014 if Cryptosporidium monitoring under the LT2ESWTR is required
------------------------------------------------------------------------

    This schedule requires wholesale systems and consecutive systems 
that are part of a combined distribution system with at least one 
system with an earlier compliance deadline to conduct their IDSE 
simultaneously so that the wholesale system will be aware of compliance 
challenges facing the consecutive systems and will be able to implement 
treatment plant, capital, and operational improvements as necessary to 
ensure compliance of both the wholesale and consecutive systems. The 
Advisory Committee and EPA both recognized that DBPs, once formed, are 
difficult to remove and are generally best addressed by treatment plant 
improvements, typically through precursor removal or use of alternative 
disinfectants. For a wholesale system to make the best decisions 
concerning the treatment steps necessary to meet TTHM and HAA5 LRAAs 
under the Stage 2 DBPR, both in its own distribution system and in the 
distribution systems of consecutive systems it serves, the wholesale 
system must know the DBP levels throughout the combined distribution 
system. Without this information, the wholesale system may design 
treatment changes that allow the wholesale system to achieve 
compliance, but leave the consecutive system out of compliance.
    In summary, the compliance schedule for today's rule maintains the 
earliest compliance dates recommended by the Advisory Committee for 
PWSs serving at least 100,000 people (plus smaller systems that are 
part of the combined distribution system). These PWSs serve the 
majority of people. The schedule also maintains the latest compliance 
dates the Advisory Committee recommended, which apply to PWSs serving 
fewer than 10,000 people. EPA has staggered compliance schedules for 
PWSs between these two size categories in order to facilitate 
implementation of the rule. This staggered schedule is consistent with 
the schedule required under the LT2ESWTR promulgated elsewhere in 
today's Federal Register.
3. Summary of Major Comments
    EPA received significant public comment on the compliance schedule 
in the August 18, 2003 proposal. Major issues raised by commenters 
include providing more time for PWSs to prepare for monitoring, giving 
States or primacy agencies more time to oversee monitoring, and 
establishing consistent schedules for consecutive PWSs. A summary of 
these comments and EPA's responses follows.
    Standard monitoring plan and system specific study plan 
preparation. Many commenters were concerned about the proposed 
requirement to develop and execute an IDSE monitoring plan without any 
primacy agency review. PWSs specifically expressed concern about the 
financial commitment without prior State approval and noted that some 
PWSs would need more than the time allowed under the proposed rule to 
develop and implement an IDSE monitoring plan, especially without an 
opportunity for State or primacy agency review and approval. Smaller 
PWSs may require substantial time and planning to budget for IDSE 
expenses, especially for systems that have not previously complied with 
DBP MCLs.
    EPA recognizes these concerns and today's final rule provides time 
for PWSs to submit IDSE plans (monitoring plans, study plans, or 40/30 
certifications) for State or primacy agency review and more time before 
having to begin monitoring. Specifically, PWSs serving 50,000 to 99,999 
people and those serving 10,000 to 49,999 people must submit IDSE plans 
about 12 months and 18 months after the effective date, respectively, 
and complete standard monitoring or a system specific study within two 
years after submitting their IDSE plan. This is significantly more time 
than was specified under the proposal, where these systems would have 
had to conduct their IDSE and submit their IDSE report 24 months after 
the effective date. PWSs serving at least 100,000 people must submit 
IDSE plans about six months after the effective date and complete 
standard monitoring or a system specific study about 30 months after 
the effective date, which also provides more time than was specified 
under the proposal. PWSs serving fewer than 10,000 people, not 
associated with a larger system in their combined distribution system, 
do not begin monitoring until more than 36 months after the effective 
date.
    EPA believes that the final compliance schedule allows PWSs 
sufficient time to develop IDSE plans with these compliance dates. The 
schedule also allows 12 months for State or primacy agency review of 
IDSE plans, which allows additional time for review and for 
coordination with systems and provides more time to address 
deficiencies in IDSE plans. This is especially important for smaller 
PWSs, which are likely to need the most assistance from States. By 
staggering monitoring start dates, today's rule also eases 
implementation by reducing the number of PWSs that will submit plans at 
any one time, when the most assistance from regulatory agencies will be 
required.
    In summary, today's schedule has been modified so that systems are 
required to submit IDSE plans for primacy agency review and approval 
prior to conducting their IDSE. Systems can consider that their plan 
has been approved if they have not heard back from the State by the end 
of the State review period. Systems are also required to conduct the 
approved monitoring and submit their IDSE report (including the 
system's recommended Stage 2 compliance monitoring) for State or 
primacy agency review on a schedule that allows for systems to still 
have a minimum of full three years to comply with Stage 2 following 
State or primacy agency review of the system's Stage 2 recommended 
monitoring. As with the review of plans, systems can consider that 
their IDSE report has been approved if they have not heard back from 
the State by the end of the State review period.
    State/primacy agency oversight. EPA is preparing to support 
implementation of IDSE requirements that must be completed prior to 
States achieving primacy. Several States have expressed concern about 
EPA providing guidance and reviewing reports from systems that the 
State has permitted, inspected, and worked with for a long time. These 
States believe that their familiarity with

[[Page 419]]

the systems enables them to make the best decisions to implement the 
rule and protect public health and that the rule requirement should be 
delayed until States receive primacy. Commenters were concerned that 
some States will not participate in early implementation activities and 
indicated that States would prefer monitoring to begin 24 months after 
rule promulgation. Commenters also noted that States need sufficient 
time to become familiar with the rule, train their staff, prepare 
primacy packages, and train PWSs.
    EPA agrees that State familiarity is an important component of the 
review and approval process, looks forward to working closely with the 
State drinking water program representatives during IDSE 
implementation, and welcomes proactive State involvement. However, the 
Agency believes that delaying implementation of risk-based IDSE 
targeting activities until States receive primacy is an unacceptable 
delay in public health protection and also inconsistent with the 
Advisory Committee's recommendations. EPA remains committed to working 
with States to the greatest extent feasible to implement today's rule, 
consistent with the schedule promulgated today. For States unable to 
actively participate in IDSE implementation, however, EPA believes it 
has an obligation to provide support and guidance to PWSs who are 
covered and independently responsible for complying with the IDSE 
requirements of today's rule and is prepared to oversee implementation. 
Moreover, EPA believes that the staggered compliance schedule in 
today's final rule will enhance States' ability to help implement the 
rule.
    Consecutive systems. Most commenters supported consecutive systems 
being on the same IDSE schedule as wholesale systems, recognizing the 
benefits of treatment plant capital and operational improvements by the 
wholesale system as the preferred method of DBP compliance, with the 
timely collection of DBP data throughout the combined distribution 
system a key component. Several commenters preferred that consecutive 
systems have a later Stage 2 compliance date to allow for evaluation of 
whether wholesale system treatment changes are adequate to ensure 
compliance and to consider changes to water delivery specifications.
    EPA disagrees with those commenters recommending a different Stage 
2 compliance date and thus has maintained the approach in the proposal, 
which keeps all systems that are part of a combined distribution system 
(the interconnected distribution system consisting of the distribution 
systems of wholesale systems and of the consecutive systems that 
receive finished water) on the same Stage 2 compliance schedule. 
Extending the Stage 2 compliance dates would unnecessarily delay the 
public health protection afforded by this rule. Consecutive systems 
must be able to evaluate whether wholesale system changes are 
sufficient to ensure compliance and, if they are not, to make cost-
effective changes to ensure compliance where wholesale system efforts 
address some, but not all, of the concerns with compliance. Public 
health protection through compliance with Stage 2 MCLs will occur on 
the schedule of the largest system for all systems in the combined 
distribution system (regardless of size). If a consecutive system must 
make capital improvements to comply with this rule, the State may use 
its existing authority to grant up to an additional 24 months to that 
system. In addition, implementation and data tracking will be 
simplified because all systems in a combined distribution system will 
be on the same IDSE and Stage 2 compliance schedule. EPA believes that 
this is a better approach from both a public health standpoint and an 
implementation standpoint.
    EPA agrees with many commenters that a high level of coordination 
among wholesaler, consecutive system, and States will be necessary to 
ensure compliance. The schedule in today's rule provides more time for 
planning, reviewing, and conducting the IDSE than the schedule in the 
proposed rule, which will allow more time for necessary coordination, 
including small consecutive systems that need help in negotiations with 
their wholesale system. EPA will work with ASDWA and States to develop 
guidance to facilitate wholesale/consecutive system cooperation. This 
additional time and the staggered schedule discussed in this section 
also lessens the laboratory burden associated with IDSE monitoring.
    The staggered schedule also helps address commenter concerns about 
evaluating combined distribution systems. Other commenters' concerns 
about time needed for developing contracts between systems and for 
planning, funding, and implementing treatment changes are addressed by 
not requiring Stage 2 compliance until at least six years following 
rule promulgation.

F. Initial Distribution System Evaluation (IDSE)

1. Today's Rule
    Today's rule establishes requirements for systems to perform an 
Initial Distribution System Evaluation (IDSE). The IDSE is intended to 
identify sample locations for Stage 2 compliance monitoring that 
represent distribution system sites with high DBP concentrations. 
Systems will develop an IDSE plan, collect data on DBP levels 
throughout their distribution system, evaluate these data to determine 
which sampling locations are most representative of high DBP levels, 
and compile this information into a report for submission to the State 
or primacy agency. Systems must complete one IDSE to meet the 
requirements of today's rule.
    a. Applicability. This requirement applies to all community water 
systems, and to large nontransient noncommunity water systems (those 
serving at least 10,000 people) that use a primary or residual 
disinfectant other than ultraviolet light, or that deliver water that 
has been treated with a primary or residual disinfectant other than 
ultraviolet light. Systems serving fewer than 500 people are covered by 
the very small system waiver provisions of today's rule and are not 
required to complete an IDSE if they have TTHM and HAA5 data collected 
under Subpart L. Consecutive systems are subject to the IDSE 
requirements of today's rule. Consecutive systems must comply with IDSE 
requirements on the same schedule as the system serving the largest 
population in the combined distribution system, as described in section 
IV.E.
    b. Data collection. For those systems not receiving a very small 
system waiver, there are three possible approaches by which a system 
can meet the IDSE requirement.
    i. Standard monitoring. Standard monitoring requires one year of 
DBP monitoring throughout the distribution system on a specified 
schedule. Prior to commencing standard monitoring, systems must prepare 
a monitoring plan and submit it to the primacy agency for review. The 
frequency and number of samples required under standard monitoring is 
determined by source water type and system size. The number of samples 
does not depend on the number of plants per system. Section IV.G 
provides a detailed discussion of the specific population-based 
monitoring requirements for IDSE standard monitoring. Although standard 
monitoring results are not to be used for determining compliance with 
MCLs,

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systems are required to include individual sample results for the IDSE 
results when determining the range of TTHM and HAA5 levels to be 
reported in their Consumer Confidence Report (see section IV.J).
    ii. System specific study. Under this approach, systems may choose 
to perform a system specific study based on earlier monitoring studies 
or distribution system hydraulic models in lieu of standard monitoring. 
Prior to commencing a system specific study, systems must prepare a 
study plan and submit it to the primacy agency for approval. The two 
options for system specific studies are: (1) TTHM and HAA5 monitoring 
data that encompass a wide range of sample sites representative of the 
entire distribution system, including those judged to represent high 
TTHM and HAA5 concentrations, and (2) extended period simulation 
hydraulic models that simulate water age in the distribution system, in 
conjunction with one round of TTHM and HAA5 sampling.
    iii. 40/30 certification. Under this approach, systems must certify 
to their State or primacy agency that every individual compliance 
sample taken under subpart L during the period specified in Table IV.F-
2 were less than or equal to 0.040 mg/L for TTHM and less than or equal 
to 0.030 mg/L for HAA5, and that there were no TTHM or HAA5 monitoring 
violations during the same period. The State or primacy agency may 
require systems to submit compliance monitoring results, distribution 
system schematics, or recommend subpart V compliance monitoring 
locations as part of the certification. This certification must be kept 
on file and submitted to the State or primacy agency for review. 
Systems that qualify for reduced monitoring for the Stage 1 DBPR during 
the two years prior to the start of the IDSE may use results of reduced 
Stage 1 DBPR monitoring to prepare the 40/30 certification. The 
requirements for the 40/30 certification are listed in Table IV.F-1.

             Table IV.F-1.--40/30 Certification Requirements
------------------------------------------------------------------------
 
------------------------------------------------------------------------
40/30 Certification Requirements..   A certification that every
                                     individual compliance sample taken
                                     under subpart L during the period
                                     specified in Table IV.F-2 were less
                                     than or equal to 0.040 mg/L for
                                     TTHM and less than or equal to
                                     0.030 mg/L for HAA5, and that there
                                     were no TTHM or HAA5 monitoring
                                     violations during the same period.
                                     Compliance monitoring
                                     results, distribution system
                                     schematics, and/or recommended
                                     subpart V compliance monitoring
                                     locations as required by the State
                                     or primacy agency.
------------------------------------------------------------------------


                 Table IV.F-2.--40/30 Eligibility Dates
------------------------------------------------------------------------
                                         Then your eligibility for 40/30
                                         certification is based on eight
                                          consecutive calendar quarters
   If your 40/30 Certification Is Due        of subpart L compliance
                                         monitoring results beginning no
                                                 earlier than\1\
------------------------------------------------------------------------
(1) October 1, 2006....................  January 2004.
(2) April 1, 2007......................  January 2004.
(3) October 1, 2007....................  January 2005.
(4) April 1, 2008......................  January 2005.
------------------------------------------------------------------------
\1\ Unless you are on reduced monitoring under subpart L and were not
  required to monitor during the specified period. If you did not
  monitor during the specified period, you must base your eligibility on
  compliance samples taken during the 12 months preceding the specified
  period.

    c. Implementation. All systems subject to the IDSE requirement 
under this final rule (except those covered by the very small system 
waiver) must prepare and submit an IDSE plan (monitoring plan for 
standard monitoring, study plan for system specific study) or 40/30 
certification to the State or primacy agency. IDSE plans and 40/30 
certifications must be submitted according to the schedule described in 
section IV.E and IV.M. The requirements for the IDSE plan depend on the 
IDSE approach that the system selects and are listed in Tables IV.F-1 
and IV.F-3.

            TABLE IV.F-3.--IDSE Monitoring Plan Requirements
------------------------------------------------------------------------
 IDSE data collection alternative          IDSE plan requirements
------------------------------------------------------------------------
Standard Monitoring...............   Schematic of the
                                     distribution system (including
                                     distribution system entry points
                                     and their sources, and storage
                                     facilities), with notes indicating
                                     locations and dates of all
                                     projected standard monitoring, and
                                     all projected subpart L compliance
                                     monitoring.
                                     Justification for all
                                     standard monitoring locations
                                     selected and a summary of data
                                     relied on to select those
                                     locations.
                                     Population served and
                                     system type (subpart H or ground
                                     water).
System Specific Study:
Hydraulic Model...................  Hydraulic models must meet the
                                     following criteria:
                                     Extended period simulation
                                     hydraulic model.
                                     Simulate 24 hour variation
                                     in demand and show a consistently
                                     repeating 24 hour pattern of
                                     residence time.
                                     Represent 75% of pipe
                                     volume; 50% of pipe length; all
                                     pressure zones; all 12-inch
                                     diameter and larger pipes; all 8-
                                     inch and larger pipes that connect
                                     pressure zones, influence zones
                                     from different sources, storage
                                     facilities, major demand areas,
                                     pumps, and control valves, or are
                                     known or expected to be significant
                                     conveyors of water; all pipes 6
                                     inches and larger that connect
                                     remote areas of a distribution
                                     system to the main portion of the
                                     system; all storage facilities with
                                     standard operations represented in
                                     the model; all active pump stations
                                     with controls represented in the
                                     model; and all active control
                                     valves.

[[Page 421]]

 
                                     The model must be
                                     calibrated, or have calibration
                                     plans, for the current
                                     configuration of the distribution
                                     system during the period of high
                                     TTHM formation potential. All
                                     storage facilities must be
                                     evaluated as part of the
                                     calibration process.
                                     All required calibration
                                     must be completed no later than 12
                                     months after plan submission.
                                    Submission must include:
                                     Tabular or spreadsheet data
                                     demonstrating percent of total pipe
                                     volume and pipe length represented
                                     in the model, broken out by pipe
                                     diameter, and all required model
                                     elements.
                                     A description of all
                                     calibration activities undertaken,
                                     and if calibration is complete, a
                                     graph of predicted tank levels
                                     versus measured tank levels for the
                                     storage facility with the highest
                                     residence time in each pressure
                                     zone, and a time series graph of
                                     the residence time at the longest
                                     residence time storage facility in
                                     the distribution system showing the
                                     predictions for the entire
                                     simulation period (i.e., from time
                                     zero until the time it takes for
                                     the model to reach a consistently
                                     repeating pattern of residence
                                     time).
                                     Model output showing
                                     preliminary 24 hour average
                                     residence time predictions
                                     throughout the distribution system.
                                     Timing and number of
                                     samples planned for at least one
                                     round of TTHM and HAA5 monitoring
                                     at a number of locations no less
                                     than would be required for the
                                     system under standard monitoring in
                                     Sec.   141.601 during the
                                     historical month of high TTHM.
                                     These samples must be taken at
                                     locations other than existing
                                     subpart L compliance monitoring
                                     locations.
                                     Description of how all
                                     requirements will be completed no
                                     later than 12 months after
                                     submission of the system specific
                                     study plan.
                                     Schematic of the
                                     distribution system (including
                                     distribution system entry points
                                     and their sources, and storage
                                     facilities), with notes indicating
                                     the locations and dates of all
                                     completed system specific study
                                     monitoring (if calibration is
                                     complete) and all subpart L
                                     compliance monitoring.
                                     Population served and
                                     system type (subpart H or ground
                                     water).
                                     If the model submitted does
                                     not fully meet the requirements,
                                     the system must correct the
                                     deficiencies and respond to State
                                     inquiries on a schedule the State
                                     approves, or conduct standard
                                     monitoring.
System Specific Study:
Existing Monitoring Results.......  Existing monitoring results must
                                     meet the following criteria:
                                     TTHM and HAA5 results must
                                     be based on samples collected and
                                     analyzed in accordance with Sec.
                                     141.131. Samples must be collected
                                     within five years of the study plan
                                     submission date.
                                     The sampling locations and
                                     frequency must meet the
                                     requirements identified in Table
                                     IV.F-4. Each location must be
                                     sampled once during the peak
                                     historical month for TTHM levels or
                                     HAA5 levels or the month of warmest
                                     water temperature for every 12
                                     months of data submitted for that
                                     location. Monitoring results must
                                     include all subpart L compliance
                                     monitoring results plus additional
                                     monitoring results as necessary to
                                     meet minimum sample requirements.
                                    Submission must include:
                                     Previously collected
                                     monitoring results
                                     Certification that the
                                     reported monitoring results include
                                     all compliance and non-compliance
                                     results generated during the time
                                     period beginning with the first
                                     reported result and ending with the
                                     most recent subpart L results.
                                     Certification that the
                                     samples were representative of the
                                     entire distribution system and that
                                     treatment and distribution system
                                     have not changed significantly
                                     since the samples were collected.
                                     Schematic of the
                                     distribution system (including
                                     distribution system entry points
                                     and their sources, and storage
                                     facilities), with notes indicating
                                     the locations and dates of all
                                     completed or planned system
                                     specific study monitoring.
                                     Population served and
                                     system type (subpart H or ground
                                     water).
                                     If a system submits
                                     previously collected data that
                                     fully meet the number of samples
                                     required for IDSE monitoring in
                                     Table IV.F-4 and some of the data
                                     are rejected due to not meeting the
                                     additional requirements, the system
                                     must either conduct additional
                                     monitoring to replace rejected data
                                     on a schedule the State approves,
                                     or conduct standard monitoring.
------------------------------------------------------------------------


                        Table IV.F-4.--SSS Existing Monitoring Data Sample Requirements.
----------------------------------------------------------------------------------------------------------------
                                                                     Number of           Number of samples
              System type                    Population size        monitoring   -------------------------------
                                                 category            locations         TTHM            HAA5
----------------------------------------------------------------------------------------------------------------
 
 Subpart H:
 
                                                            <500               3               3               3
 
                                                       500-3,300               3               9               9
 
                                                     3,301-9,999               6              36              36
 
                                                   10,000-49,999              12              72              72
 
                                                  50,000-249,999              24             144             144
 
                                                 250,000-999,999              36             216             216

[[Page 422]]

 
 
                                             1,000,000-4,999,999              48             288             288
 
                                                    >= 5,000,000              60             360             360
 
 Ground Water:                                              <500               3               3               3
 
                                                       500-9,999               3               9               9
 
                                                   10,000-99,999              12              48              48
 
                                                 100,000-499,999              18              72              72
 
                                                      >= 500,000              24              96              96
----------------------------------------------------------------------------------------------------------------

    The State or primacy agency will approve the IDSE plan or 40/30 
certification, or request modifications. If the State or primacy agency 
has not taken action by the date specified in section IV.E or has not 
notified the system that review is not yet complete, systems may 
consider their submissions to be approved. Systems must implement the 
IDSE option described in the IDSE plan approved by the State or primacy 
agency according to the schedule described in section IV.E.
    All systems completing standard monitoring or a system specific 
study must submit a report to the State or primacy agency according to 
the schedule described in section IV.E. Systems that have completed 
their system specific study at the time of monitoring plan submission 
may submit a combined monitoring plan and report on the required 
schedule for IDSE plan submissions. The requirements for the IDSE 
report are listed in Table IV.F-5. Some of these reporting requirements 
have changed from the proposal to reduce reporting and paperwork burden 
on systems.

                 TABLE IV.F-5.--IDSE Report Requirements
------------------------------------------------------------------------
 IDSE data collection alternative         IDSE report requirements
------------------------------------------------------------------------
Standard Monitoring...............   All subpart L compliance
                                     monitoring and standard monitoring
                                     TTHM and HAA5 analytical results in
                                     a tabular format acceptable to the
                                     State.
                                     If changed from the
                                     monitoring plan, a schematic of the
                                     distribution system, population
                                     served, and system type.
                                     An explanation of any
                                     deviations from the approved
                                     monitoring plan.
                                     Recommendations and
                                     justifications for subpart V
                                     compliance monitoring locations and
                                     timing.
System Specific Study.............   All subpart L compliance
                                     monitoring and all system specific
                                     study monitoring TTHM and HAA5
                                     analytical results conducted during
                                     the period of the system specific
                                     study in a tabular or spreadsheet
                                     form acceptable to the State.
                                     If changed from the study
                                     plan, a schematic of the
                                     distribution system, population
                                     served, and system type.
                                     If using the modeling
                                     provision, include final
                                     information for required plan
                                     submissions and a 24-hour time
                                     series graph of residence time for
                                     each subpart V compliance
                                     monitoring location selected.
                                     An explanation of any
                                     deviations from the original study
                                     plan.
                                     All analytical and modeling
                                     results used to select subpart V
                                     compliance monitoring locations
                                     that show that the system specific
                                     study characterized TTHM and HAA5
                                     levels throughout the entire
                                     distribution system.
                                     Recommendations and
                                     justifications for subpart V
                                     compliance monitoring locations and
                                     timing.
------------------------------------------------------------------------

    All systems must prepare Stage 2 compliance monitoring 
recommendations. All IDSE reports must include recommendations for 
Stage 2 compliance monitoring locations and sampling schedule. Systems 
submitting a 40/30 certification must include their Stage 2 compliance 
monitoring recommendations in their Stage 2 (Subpart V) monitoring plan 
unless the State requests Subpart V site recommendations as part of the 
40/30 certification. The number of sampling locations and the criteria 
for their selection are described in Sec.  141.605 of today's final 
rule, and in section IV.G. Generally, a system must recommend locations 
with the highest LRAAs unless it provides a rationale (such as ensuring 
geographical coverage of the distribution system instead of clustering 
all sites in a particular section of the distribution system) for 
selecting other locations. In evaluating possible Stage 2 compliance 
monitoring locations, systems must consider both Stage 1 DBPR 
compliance data and IDSE data.
    The State or primacy agency will approve the IDSE report or request 
modifications. If the State or primacy agency has not taken action by 
the date specified in section IV.E or has not notified the system that 
review is not yet complete, systems may consider their submission to be 
approved and prepare to begin Stage 2 compliance monitoring.
    EPA has developed the Initial Distribution System Evaluation 
Guidance Manual for the Final Stage 2 Disinfectants and Disinfection 
Byproducts Rule (USEPA 2006) to assist systems with implementing each 
of these requirements. This guidance may be requested from EPA's Safe 
Drinking

[[Page 423]]

Water Hotline, which may be contacted as described under FOR FURTHER 
INFORMATION CONTACT in the beginning of this notice. This guidance 
manual is also available on the EPA Web site at http://www.epa.gov/
safewater/stage2/index.html.
2. Background and Analysis
    In the Stage 2 DBPR proposal (USEPA, 2003a), EPA proposed 
requirements for systems to complete an IDSE. The Agency based its 
proposal upon the Stage 2 M-DBP Advisory Committee recommendations in 
the Agreement in Principle. The Advisory Committee believed and EPA 
concurs that maintaining Stage 1 DBPR monitoring sites for the Stage 2 
DBPR would not accomplish the risk-targeting objective of minimizing 
high DBP levels and providing consistent and equitable protection 
across the distribution system. Most of these requirements have not 
changed from the proposed rule.
    The data collection requirements of the IDSE are designed to find 
both high TTHM and high HAA5 sites (see section IV.G for IDSE 
monitoring requirements). High TTHM and HAA5 concentrations often occur 
at different locations in the distribution system. The Stage 1 DBPR 
monitoring sites identified as the maximum location are selected 
according to residence time. HAAs can degrade in the distribution 
system in the absence of sufficient disinfectant residual (Baribeau et 
al. 2000). Consequently, residence time is not an ideal criterion for 
identifying high HAA5 sites. In addition, maximum residence time 
locations that are associated with high TTHM levels may not be constant 
due to daily or seasonal changes in demand. The analysis of maximum 
residence time completed for the selection of Stage 1 monitoring sites 
may not have been capable of detecting these variations. The 
Information Collection Rule data show that over 60 percent of the 
highest HAA5 LRAAs and 50 percent of the highest TTHM LRAAs were found 
at sampling locations in the distribution system other than the maximum 
residence time compliance monitoring location (USEPA 2003a). Therefore, 
the method and assumptions used to select the Information Collection 
Rule monitoring sites and the Stage 1 DBPR compliance monitoring sites 
may not reliably capture high DBP levels for Stage 2 DBPR compliance 
monitoring sites.
    a. Standard monitoring. The Advisory Committee recommended that 
systems sample throughout the distribution system at twice the number 
of locations as required under Stage 1 and, using these results in 
addition to Stage 1 compliance data, identify high DBP locations. 
Monitoring at additional sites increases the chance of finding sites 
with high DBP levels and targets both DBPs that degrade and DBPs that 
form as residence time increases in the distribution system. EPA 
believes that the required number of standard monitoring locations plus 
Stage 1 monitoring results will provide an adequate characterization of 
DBP levels throughout the distribution system at a reasonable cost. By 
revising Stage 2 compliance monitoring plans to target locations with 
high DBPs, systems will be required to take steps to address high DBP 
levels at locations that might otherwise have gone undetected.
    The Advisory Committee recommended that an IDSE be performed by all 
community water systems, unless the system had sufficiently low DBP 
levels or is a very small system with a simple distribution system. EPA 
believes that large nontransient noncommunity water systems (NTNCWS) 
(those serving at least 10,000 people) also have distribution systems 
that require further evaluation to determine the locations most 
representative of high DBP levels and proposed that they be required to 
conduct an IDSE. Therefore, large NTNCWS and all community water 
systems are required to comply with IDSE requirements under today's 
final rule, unless they submit a 40/30 certification or they are 
covered by the very small system waiver provisions.
    b. Very small system waivers. Systems serving fewer than 500 people 
that have taken samples under the Stage 1 DBPR will receive a very 
small system waiver. EPA proposed and the Advisory Committee 
recommended a very small system waiver following a State determination 
that the existing Stage 1 compliance monitoring location adequately 
characterizes both high TTHM and high HAA5 for the distribution system 
because many very small systems have small or simple distribution 
systems. The final rule grants the very small system waiver to all 
systems serving fewer than 500 that have Stage 1 DBPR data. This 
provision was changed from the proposal to reflect that most very small 
systems that sample under the Stage 1 DBPR have sampling locations that 
are representative of both high TTHM and high HAA5 because most very 
small systems have small and simple distribution systems. In addition, 
many very small systems are ground water systems that typically have 
stable DBP levels that tend to be lower than surface water DBP levels. 
NRWA survey data show that free chlorine residual in very small systems 
(serving <500) at both average residence time and maximum residence 
time locations are lower than levels at both of those locations in 
larger systems, and the change in residual concentration between those 
two locations is smaller in very small systems compared to larger sized 
systems. The magnitude of the reduction in residual concentration gives 
an indication of how much disinfectant has reacted to form DBPs, 
including TTHM and HAA5. The smaller reduction in disinfectant 
concentration between average residence time and maximum residence time 
in very small systems compared to larger systems indicates that DBP 
formation potential is probably lower in very small systems compared to 
larger systems, and the likelihood for significant DBP variation within 
the distribution system of very small systems is low if the 
distribution system is small and not complex. However, there may be 
some small systems with extended or complex distribution systems that 
should be studied further to determine new sampling locations. For this 
reason, States or primacy agencies can require any particular very 
small system to conduct an IDSE. Very small systems subject to the 
Stage 2 DBPR that do not have a Stage 1 compliance monitoring location 
may monitor in accordance with the Stage 1 DBPR provisions to be 
eligible for this waiver.
    c. 40/30 certifications. Systems that certify to their State or 
primacy agency that all compliance samples taken during eight 
consecutive calendar quarters prior to the start of the IDSE were 
<=0.040 mg/L TTHM and <=0.030 mg/L HAA5 are not required to collect 
additional DBP monitoring data under the IDSE requirements as long as 
the system has no TTHM or HAA5 monitoring violations. These criteria 
were developed because both EPA and the AdvisoryCommittee determined 
that these systems most likely would not have DBP levels that exceed 
the MCLs. Systems must have qualifying TTHM and HAA5 data for eight 
consecutive calendar quarters according to the schedule in Table IV.F-2 
to be eligible for this option. Systems on reduced monitoring that did 
not monitor during the specified time period may use data from the 
prior year to meet the 40/30 certification criteria. Systems that have 
not previously conducted Stage 1 DBPR compliance monitoring may begin 
such monitoring to collect the data necessary to qualify for 40/30 
certification. The certification and data supporting it must be 
available to the public upon request.

[[Page 424]]

    The qualifying time period for the 40/30 certification has changed 
from the proposed rule.
    Under the proposed rule, the rule language identified a specific 
two year window with start and end dates. In today's final rule, the 
qualifying time period has been changed to ``eight consecutive calendar 
quarters of subpart L compliance monitoring results beginning no 
earlier than * * *'' (see Table IV.F-2). This change was made so that 
systems that have made a treatment change within the two years prior to 
rule promulgation and have collected initial data that meet the 40/30 
criteria might have the opportunity to collect eight consecutive 
quarters of qualifying data and apply for a 40/30 certification. This 
schedule change also allows systems that have not previously monitored 
under Stage 1 an opportunity to qualify for a 40/30 certification.
    Under the proposed Stage 2 DBPR, systems that missed the deadline 
for submitting a 40/30 certification would be required to conduct 
either standard monitoring or a system specific study even if the 
system otherwise qualified for the 40/30 certification. Under today's 
final rule, systems that do not make any submission by the IDSE plan 
submission deadline will still receive a violation, but may submit a 
late 40/30 certification if their data meet the requirements. This 
change was made so that systems and primacy agencies do not spend time 
preparing and reviewing standard monitoring plans and IDSE reports for 
systems with a low likelihood of finding high TTHM and HAA5 levels.
    The reporting requirements for this provision have been reduced 
from the requirements in the proposed rulemaking. In the proposal, 
systems qualifying for the 40/30 certification were required to submit 
all qualifying data and provide recommendations for Stage 2 compliance 
monitoring locations. The final rule requires systems to submit a 
certification that their data meet all the requirements of the 40/30 
certification and to include their Stage 2 compliance monitoring 
recommendations in their Stage 2 monitoring plan. These changes were 
made to reduce the reporting burden on systems that qualify for the 40/
30 certification and to maintain consistency with monitoring plan 
requirements under the Stage 1 DBPR. This approach also gives systems 
more time to select appropriate monitoring sites for Stage 2 compliance 
monitoring. The State or primacy agency may request systems to submit 
the data, a distribution system schematic, and/or recommendations for 
Stage 2 compliance monitoring as part of the 40/30 certification. This 
provision was included to facilitate primacy agency review of 40/30 
certifications; the additional information is only required if 
requested by the primacy agency.
    d. System specific studies. Advisory Committee members recognized 
that some systems have detailed knowledge of their distribution systems 
by way of ongoing hydraulic modeling and/or existing widespread 
monitoring plans (beyond that required for compliance monitoring) that 
would provide equivalent or superior monitoring site selection 
information compared to standard monitoring. Therefore, the Advisory 
Committee recommended that such systems be allowed to determine new 
monitoring sites using system-specific data such as hydraulic model 
results or existing monitoring data; this provision remains in the 
final rule. In the proposed rule, the only specification for SSSs was 
to identify monitoring sites that would be equivalent or superior to 
those identified under Standard Monitoring. The final rule includes 
more specific requirements on how these studies should be completed. 
The requirements in the final rule were developed to be consistent with 
the proposal, yet more specific to help systems better understand 
expectations under this provision and lessen the chances of a study 
plan not being approved.
    The new modeling requirements were developed to reflect that 
hydraulic models can identify representative high TTHM monitoring 
locations by predicting hydraulic residence time in the distribution 
system. Water age has been found to correlate with TTHM formation in 
the distribution system. Consequently, for this system specific study 
approach, hydraulic residence time predicted by the model is used as a 
surrogate for TTHM formation to locate appropriate Stage 2 compliance 
monitoring locations. To predict hydraulic residence time in the 
distribution system, the model must represent most of the distribution 
system and must have been calibrated recently and appropriately to 
reflect water age in the distribution system. Requirements to reflect 
this are in today's rule. All storage facilities must be evaluated for 
the calibration, and systems using this option must submit a graph of 
predicted tank levels versus measured tank levels for the storage 
facility with the highest residence time in each pressure zone. These 
calibration requirements are focused on storage facilities because they 
are the largest controlling factor for water age in the distribution 
system. The calibration requirements reflect the fact that the purpose 
of the model is to predict water age. ICR data show that HAA5 data do 
not necessarily correlate well with water age (USEPA 2003a). Because 
the purpose of the IDSE is to locate representative high locations for 
both TTHM and HAA5, one round of monitoring must be completed at 
potential Stage 2 compliance monitoring locations to determine 
appropriate HAA5 monitoring locations during the historical high month 
of TTHM concentrations. The number of locations must be no less than 
would be required under standard monitoring.
    Preliminary average residence time data are required as a part of 
the study plan for systems to demonstrate that their distribution 
system hydraulic model is able to produce results for water age 
throughout the distribution system, even though calibration may not be 
complete. Systems also need to describe their plans to complete the 
modeling requirements within 12 months of submitting the study plan. 
These last two requirements were developed so that States can be 
assured that systems have the technical capacity to complete their 
modeling requirements by the IDSE report deadline. If systems cannot 
demonstrate that they are in a position to complete the modeling 
requirements according to the required schedule, they will be required 
to complete standard monitoring.
    All new modeling requirements were added to help systems 
demonstrate how their model will fulfill the purpose and requirements 
of the IDSE and to assist primacy agencies with approval 
determinations. The associated reporting requirements were developed to 
balance the needs of systems to demonstrate that they have fulfilled 
the requirements and the needs of primacy agency reviewers to be able 
to understand the work completed by the system.
    EPA has specified new requirements for systems complete an SSS 
using existing monitoring data to help systems understand the extent of 
historical data that would meet the requirements of the IDSE. The 
number of required sample locations and samples are consistent with 
sampling requirements under standard monitoring and the recommendations 
made by the Advisory Committee. The Advisory Committee recommended that 
systems complete an IDSE sample at twice the number of sites required 
by the Stage 1 DBPR in addition to Stage 1 DBPR sampling. Because the 
number of required Stage 1 DBPR monitoring locations varies within each 
population category under

[[Page 425]]

the Stage 1 plant-based monitoring approach (since systems have 
different numbers of plants), EPA used the number of required Standard 
Monitoring locations plus the number of Stage 2 compliance monitoring 
locations to develop minimum requirements for the use of existing 
monitoring data for the SSS. The number of required locations and 
samples are shown in Table IV.F-4. Systems will use their Stage 1 
monitoring results plus additional non-compliance or operational 
samples to fulfill these requirements. Small systems with many plants 
may have been collecting a disproportionate number of samples under the 
Stage 1 DBPR compared to the population based monitoring requirements 
presented in today's rule and may have sufficient historical data to 
characterize the entire distribution system. These requirements allow 
those systems to submit an SSS based on existing Stage 1 monitoring 
results, and they also accommodate systems that have been completing 
additional monitoring throughout the distribution system.
    The requirement to sample during the historical month of high TTHM, 
high HAA5, or warmest water temperature during each year for which data 
were collected was added to maintain consistency with the standard 
monitoring requirements where each location must be sampled one time 
during the peak historical month. Samples that qualify for this SSS 
must have been collected within five years of the study plan submission 
date and must reflect the current configuration of treatment and the 
distribution system. Five years was selected as a cut off for eligible 
data so that all data submitted would be reasonably representative of 
current source water conditions and DBP formation within the 
distribution system. Data that are older may not reflect current DBP 
formation potential in the distribution system. Five years prior to the 
submission of the study plan also correlates with the signing of the 
Agreement in Principle where the Advisory Committee made the 
recommendation for this provision. Systems interested in using this 
provision would have started eligible monitoring after the agreement 
was signed.
    Systems that submit existing monitoring data must submit all Stage 
1 sample results from the beginning of the SSS to the time when the SSS 
plan is submitted. The purpose of this requirement is to demonstrate 
that there have been no significant changes in source water quality 
since the first samples were collected, especially if all existing 
monitoring results were taken during the earliest eligible dates. 
Again, these clarifications were made so that systems could better 
understand the extent of data necessary for a monitoring plan to be 
deemed acceptable and be confident that efforts to complete an SSS 
would be found acceptable to the State or primacy agency.
    e. Distribution System Schematics. EPA has considered security 
concerns that may result from the requirement for systems to submit a 
distribution system schematic as part of their IDSE plan. EPA believes 
that the final rule strikes an appropriate balance between security 
concerns and the need for States and primacy agencies to be able to 
review IDSE plans. EPA has developed guidance for systems on how to 
submit a distribution system schematic that does not include sensitive 
information.
3. Summary of Major Comments
    The Agency received significant comments on the following issues 
related to the proposed IDSE requirements: Waiver limitations, and 
State or primacy agency review of IDSE plans.
    In the proposed rule, EPA requested comment on what the appropriate 
criteria should be for States or primacy agencies to grant very small 
system waivers. Commenters responded with a wide range of suggestions 
including support for the proposal as written, different population 
cut-offs, State or primacy agency discretion on what system size should 
qualify for the waiver, and alternative waiver criteria such as pipe 
length or number of booster stations. There was no consensus among the 
commenters on what changes should be made to the proposal for the very 
small system waiver requirements. EPA did not change the population 
cutoff for the very small system waiver because analysis of NRWA survey 
data also showed that systems serving fewer than 500 had different 
residence times and lower free chlorine residual concentrations 
compared to other population categories, indicating that larger systems 
have different DBP formation characteristics compared to very small 
systems. Some of the suggested changes for very small system waiver 
criteria may require data that are not readily available to systems 
(such as pipe length in service) and for which there were no specific 
criteria proposed or recommended by the commenters. Implementation of 
subjective very small system waiver criteria would result in reduced 
public health protection from the rule by allowing higher DBP levels to 
go undetected.
    In addition to addressing the very small system waivers, commenters 
suggested that different criteria should be used for the 40/30 
certification, such as higher minimum DBP levels, cut-offs of 40/30 as 
LRAAs or RAAs rather than single sample maximums, or State or primacy 
agency discretion on which systems should qualify for 40/30 
certification. There was no consensus among the commenters on what 
changes should be made to the proposal for the 40/30 certification 
requirements. EPA did not change the requirements for the 40/30 
certification eligibility because the recommended alternatives were not 
technically superior to the requirements of the proposed rule. 
Implementation of 40/30 criteria using an LRAA or RAA would result in 
reduced public health protection from the rule by allowing higher DBP 
levels to go undetected. EPA did change the eligibility dates and 
reporting requirements for the 40/30 certification to reduce the burden 
on the system. Under today's final rule, States or primacy agencies can 
request TTHM and HAA5 data as desired for a more in-depth review of a 
system's qualifications.
    Many commenters expressed concern over the implementation schedule 
for the IDSE. Commenters were especially concerned that IDSE plans 
would be developed and implemented prior to State primacy, and once 
States receive primacy, they might not support the IDSE plan and would 
reject the results of the completed IDSE. To address this issue, 
commenters requested the opportunity for States to review the IDSE 
plans prior to systems completing their IDSEs. In today's rule EPA has 
modified the compliance schedule for the Stage 2 DBPR so that systems 
have the opportunity to complete their IDSE plan and have it reviewed 
by the primacy agency prior to completing the IDSE to address the 
concern that States or primacy agencies may reject the results of the 
completed IDSE. The changes to the compliance schedule are discussed 
further in section IV.E.

G. Monitoring Requirements and Compliance Determination for TTHM and 
HAA5 MCLs

    EPA is finalizing monitoring requirements under a population-based 
approach described in this section. EPA believes the population-based 
approach will provide more representative high DBP concentrations 
throughout distribution systems than would plant-based monitoring, is 
equitable, and will simplify implementation for both States and 
systems. For these reasons, EPA believes this approach is more 
appropriate than the proposed plant-

[[Page 426]]

based monitoring. Detailed discussion of the two approaches is 
presented in the preamble of the proposed rule (USEPA 2003a) and EA for 
today's rule (USEPA 2005a).
1. Today's Rule
    Today's rule establishes TTHM and HAA5 monitoring requirements for 
all systems based on a population-based monitoring approach instead of 
a plant-based approach. Under the population-based approach, monitoring 
requirements are based solely on the retail population served and the 
type of source water used and not influenced by the number of treatment 
plants or entry points in the distribution system as in previous rules 
(i.e., TTHM Rule (USEPA 1979) and Stage 1 DBPR (USEPA 1998a)).
    a. IDSE Monitoring. All systems conducting IDSE standard monitoring 
must collect samples during the peak historical month for DBP levels or 
water temperature; this will determine their monitoring schedule. Table 
IV.G-1 contains the IDSE monitoring frequencies and locations for all 
source water and size category systems. Section IV.F identifies other 
approaches by which systems can meet IDSE requirements.

                                                Table IV.G-1.--IDSE Monitoring Frequencies and Locations
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                   Distribution system monitoring locations \1\
                                                                                        ----------------------------------------------------------------
          Source water type                Population size       Monitoring periods and   Total per                  Average
                                               category          frequency of sampling    monitoring   Near entry   residence    High TTHM    High HAA5
                                                                                            period       points        time      locations    locations
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subpart H
                                       <500 consecutive         one (during peak                   2            1  ...........            1
                                        systems.                 historical month) \2\.
                                       <500 non-consecutive     .......................            2  ...........  ...........            1            1
                                        systems.
--------------------------------------
                                       500-3,300 non-           four (every 90 days)...            2            1  ...........            1  ...........
                                        consecutive systems.
                                       500-3,300 consecutive    .......................            2  ...........  ...........            1            1
                                        systems.
--------------------------------------
                                       3,301-9,999............  .......................            4  ...........            1            2            1
                                       10,000-49,999..........  six (every 60 days)....            8            1            2            3            2
                                       50,000-249,999.........  .......................           16            3            4            5            4
                                       250,000-999,999........  .......................           24            4            6            8            6
                                       1,000,000-4,999,999....  .......................           32            6            8           10            8
                                       >=5,000,000............  .......................           40            8           10           12           10
======================================
Ground Water
                                       <500 consecutive         one (during peak                   2            1  ...........            1  ...........
                                        systems.                 historical month) \2\.
--------------------------------------
                                       <500 non-consecutive     .......................            2  ...........  ...........            1            1
                                        systems.
                                       500-9,999..............  four (every 90 days)...            2  ...........  ...........            1            1
                                       10,000-99,999..........  .......................            6            1            1            2            2
                                       100,000-499,999........  .......................            8            1            1            3            3
                                       >=500,000..............  .......................           12            2            2            4           4
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ A dual sample set (i.e., a TTHM and an HAA5 sample) must be taken at each monitoring location during each monitoring period.
\2\ The peak historical month is the month with the highest TTHM or HAA5 levels or the warmest water temperature.

    b. Routine Stage 2 Compliance Monitoring. For all systems 
conducting either standard monitoring or a system specific study, 
initial Stage 2 compliance monitoring locations are based on the 
system's IDSE results, together with an analysis of a system's Stage 1 
DBPR compliance monitoring results. Systems receiving 40/30 
certification or a very small system waiver, and nontransient 
noncommunity water systems serving <10,000 not required to conduct an 
IDSE, base Stage 2 initial compliance monitoring locations on the 
system's Stage 1 DBPR compliance monitoring results. Some of these 
systems may also need an evaluation of distribution system 
characteristics to identify additional monitoring locations, if 
required by the transition from plant-based monitoring to population-
based monitoring.
    Systems recommend Stage 2 monitoring locations generally by 
arraying results of IDSE standard monitoring (or system specific study 
results) and Stage 1 compliance monitoring by monitoring location (from 
highest to lowest LRAA for both TTHM and HAA5). Using the protocol in 
Sec.  141.605(c) of today's rule, systems then select the required 
number of locations. Larger systems include existing Stage 1 monitoring 
locations in order to be able to have historical continuity for 
evaluating how changes in operations or treatment affect DBP levels. 
Systems may also recommend locations with lower levels of DBPs that 
would not be picked up by the protocol if they provide a rationale for 
the recommendation. Examples of rationales include ensuring better 
distribution system or population coverage (not having all locations in 
the same area) or maintaining existing locations with DBP levels that 
are nearly as high as those that would otherwise be selected. The State 
or primacy agency will review these recommendations as part of the 
review of the IDSE report submitted by systems that conducted standard 
monitoring or a system specific study.
    Table IV.G-2 contains the routine Stage 2 TTHM and HAA5 compliance

[[Page 427]]

monitoring requirements for all systems (both non-consecutive and 
consecutive systems), as well as the protocol for Stage 2 compliance 
monitoring location selection in the IDSE report. Systems that do not 
have to submit an IDSE report (those receiving a 40/30 certification or 
very small system waiver and nontransient noncommunity water systems 
serving <10,000) must conduct Stage 2 compliance monitoring as 
indicated in the ``Total per monitoring period'' column at current 
Stage 1 compliance monitoring locations, unless the State or primacy 
agency specifically directs otherwise. All systems are then required to 
maintain and follow a Stage 2 compliance monitoring plan.

                                          Table IV.G-2. Routine Compliance Monitoring Frequencies and Locations
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                 Distribution system monitoring location
                                                                                          ---------------------------------------------------
                                                                                                                                    Existing
          Source water type            Population size category   Monitoring frequency\1\   Total per     Highest      Highest     Subpart L
                                                                                            monitoring      TTHM         HAA5      compliance
                                                                                            period\2\    locations    locations    locations
---------------------------------------------------------------------------------------------------------------------------------------------
Subpart H:
                                       <500....................  per year................            2            1            1  ...........
                                       500-3,300...............  per quarter.............            2            1            1  ...........
                                       3,301-9,999.............  per quarter.............            2            1            1  ...........
                                       10,000-49,999...........  per quarter.............            4            2            1            1
                                       50,000-249,999..........  per quarter.............            8            3            3            2
                                       250,000-999,999.........  per quarter.............           12            5            4            3
                                       1,000,000-4,999,999.....  per quarter.............           16            6            6            4
                                       >= 5,000,000............  per quarter.............           20            8            7            5
Ground water:
                                       <500....................  per year................            2            1            1  ...........
                                       500-9,999...............  per year................            2            1            1  ...........
                                       10,000-99,999...........  per quarter.............            4            2            1            1
                                       100,000-499,999.........  per quarter.............            6            3            2            1
                                       >= 500,000..............  per quarter.............            8            3            3           2
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ All systems must monitor during month of highest DBP concentrations.
\2\ Systems on quarterly monitoring must take dual sample sets every 90 days at each monitoring location, except for subpart H systems serving 500-
  3,300. Systems on annual monitoring and subpart H systems serving 500-3,300 are required to take individual TTHM and HAA5 samples (instead of a dual
  sample set) at the locations with the highest TTHM and HAA5 concentrations, respectively. Only one location with a dual sample set per monitoring
  period is needed if highest TTHM and HAA5 concentrations occur at the same location, and month, if monitored annually).

    Today's rule provides States the flexibility to specify alternative 
Stage 2 compliance monitoring requirements (but not alternative IDSE 
monitoring requirements) for multiple consecutive systems in a combined 
distribution system. As a minimum under such an approach, each 
consecutive system must collect at least one sample among the total 
number of samples required for the combined distribution system and 
will base compliance on samples collected within its distribution 
system. The consecutive system is responsible for ensuring that 
required monitoring is completed and the system is in compliance. It 
also must document its monitoring strategy as part of its subpart V 
monitoring plan.
    Consecutive systems not already conducting disinfectant residual 
monitoring under the Stage 1 DBPR must comply with the monitoring 
requirements and MRDLs for chlorine and chloramines. States may use the 
provisions of Sec.  141.134(c) to modify reporting requirements. For 
example, the State may require that only the consecutive system 
distribution system point-of-entry disinfectant concentration be 
reported to demonstrate MRDL compliance, although monitoring 
requirements may not be reduced.
    i. Reduced monitoring. Systems can qualify for reduced monitoring, 
as specified in Table IV.G-3, if the LRAA at each location is <=0.040 
mg/L for TTHM and <=0.030 mg/L for HAA5 based on at least one year of 
monitoring at routine compliance monitoring locations. Systems may 
remain on reduced monitoring as long as the TTHM LRAA is <=0.040 mg/L 
and the HAA5 LRAA is <=0.030 mg/L at each monitoring location for 
systems with quarterly reduced monitoring. If the LRAA at any location 
exceeds either 0.040 mg/L for TTHM or 0.030 mg/L for HAA5 or if the 
source water annual average TOC level, before any treatment, exceeds 
4.0 mg/L at any of the system's treatment plants treating surface water 
or ground water under the direct influence of surface water, the system 
must resume routine monitoring. For systems with annual or less 
frequent reduced monitoring, systems may remain on reduced monitoring 
as long as each TTHM sample is <=0.060 mg/L and each HAA5 sample is 
<=0.045 mg/L. If the annual (or less frequent) sample at any location 
exceeds either 0.060 mg/L for TTHM or 0.045 mg/L for HAA5, or if the 
source water annual average TOC level, before any treatment, exceeds 
4.0 mg/L at any treatment plant treating surface water or ground water 
under the direct influence of surface water, the system must resume 
routine monitoring.

                                   Table IV.G-3.--Reduced Monitoring Frequency
----------------------------------------------------------------------------------------------------------------
                                                                                         Distribution system
         Source water type               Population size     Monitoring frequency 1    monitoring location per
                                            category                                      monitoring period
----------------------------------------------------------------------------------------------------------------
Subpart H:
                                     <500..................  ......................  Monitoring may not be
                                                                                      reduced.

[[Page 428]]

 
                                     500-3,300.............  per year..............  1 TTHM and 1 HAA5 sample:
                                                                                      one at the location and
                                                                                      during the quarter with
                                                                                      the highest TTHM single
                                                                                      measurement, one at the
                                                                                      location and during the
                                                                                      quarter with the highest
                                                                                      HAA5 single measurement; 1
                                                                                      dual sample set per year
                                                                                      if the highest TTHM and
                                                                                      HAA5 measurements occurred
                                                                                      at the same location and
                                                                                      quarter.
                                     3,301-9,999...........  per year..............  2 dual sample sets: one at
                                                                                      the location and during
                                                                                      the quarter with the
                                                                                      highest TTHM single
                                                                                      measurement, one at the
                                                                                      location and during the
                                                                                      quarter with the highest
                                                                                      HAA5 single measurement.
                                     10,000-49,999.........  per quarter...........  2 dual sample sets at the
                                                                                      locations with the highest
                                                                                      TTHM and highest HAA5
                                                                                      LRAAs.
                                     50,000-249,999........  per quarter...........  4 dual sample sets--at the
                                                                                      locations with the two
                                                                                      highest TTHM and two
                                                                                      highest HAA5 LRAAs.
                                     250,000-999,999.......  per quarter...........  6 dual sample sets--at the
                                                                                      locations with the three
                                                                                      highest TTHM and three
                                                                                      highest HAA5 LRAAs
                                     1,000,000-4,999,999...  per quarter...........  8 dual sample sets--at the
                                                                                      locations with the four
                                                                                      highest TTHM and four
                                                                                      highest HAA5 LRAAs.
                                     >=5,000,000...........  per quarter...........  10 dual sample sets--at the
                                                                                      locations with the five
                                                                                      highest TTHM and five
                                                                                      highest HAA5 LRAAs.
Ground Water:
                                     <500..................  every third year......  1 TTHM and 1 HAA5 sample:
                                                                                      one at the location and
                                                                                      during the quarter with
                                                                                      the highest TTHM single
                                                                                      measurement, one at the
                                                                                      location and during the
                                                                                      quarter with the highest
                                                                                      HAA5 single measurement; 1
                                                                                      dual sample set per year
                                                                                      if the highest TTHM and
                                                                                      HAA5 measurements occurred
                                                                                      at the same location and
                                                                                      quarter.
                                     500-9,999.............  per year..............  1 TTHM and 1 HAA5 sample:
                                                                                      one at the location and
                                                                                      during the quarter with
                                                                                      the highest TTHM single
                                                                                      measurement, one at the
                                                                                      location and during the
                                                                                      quarter with the highest
                                                                                      HAA5 single measurement; 1
                                                                                      dual sample set per year
                                                                                      if the highest TTHM and
                                                                                      HAA5 measurements occurred
                                                                                      at the same location and
                                                                                      quarter.
                                     10,000-99,999.........  per year..............  2 dual sample sets: one at
                                                                                      the location and during
                                                                                      the quarter with the
                                                                                      highest TTHM single
                                                                                      measurement, one at the
                                                                                      location and during the
                                                                                      quarter with the highest
                                                                                      HAA5 single measurement.
                                     100,000-499,999.......  per quarter...........  2 dual sample sets; at the
                                                                                      locations with the highest
                                                                                      TTHM and highest HAA5
                                                                                      LRAAs.
                                     >=500,000.............  per quarter...........  4 dual sample sets at the
                                                                                      locations with the two
                                                                                      highest TTHM and two
                                                                                      highest HAA5 LRAAs.
----------------------------------------------------------------------------------------------------------------
1 Systems on quarterly monitoring must take dual sample sets every 90 days.

    ii. Compliance determination. A PWS is in compliance when the 
annual sample or LRAA of quarterly samples is less than or equal to the 
MCLs. If an annual sample exceeds the MCL, the system must conduct 
increased (quarterly) monitoring but is not immediately in violation of 
the MCL. The system is out of compliance if the LRAA of the quarterly 
samples for the past four quarters exceeds the MCL.
    Monitoring and MCL violations are assigned to the PWS where the 
violation occurred. Several examples are as follows:
     If monitoring results in a consecutive system indicate an 
MCL violation, the consecutive system is in violation because it has 
the legal responsibility for complying with the MCL under State/EPA 
regulations. The consecutive system may set up a contract with its 
wholesale system that details water quality delivery specifications.
     If a consecutive system has hired its wholesale system 
under contract to monitor in the consecutive system and the wholesale 
system fails to monitor, the consecutive system is in violation because 
it has the legal responsibility for monitoring under State/EPA 
regulations.
     If a wholesale system has a violation and provides that 
water to a consecutive system, the wholesale system is in violation. 
Whether the consecutive system is in violation will depend on the 
situation. The consecutive system will also be in violation unless it 
conducted monitoring that showed that the violation was not present in 
the consecutive system.
2. Background and Analysis
    EPA proposed the plant-based approach for all systems that produce 
some or all of their finished water and the population-based monitoring 
approach for systems purchasing all of their finished water year-round. 
As part of the proposal, EPA presented a monitoring cost analysis for 
applying this approach to all systems in the Economic Analysis to 
better understand the impacts of using the population-based approach.
    The plant-based approach was adopted from the 1979 TTHM rule and 
the Stage 1 DBPR and was derived from the generally valid assumption 
that, as systems increase in size, they tend to have more plants and 
increased complexity. During the development of the Stage 2 proposal, 
EPA identified a number of issues associated with the use of the plant-
based monitoring approach. These included: (1) Plant-based monitoring 
is not as effective as population-based monitoring in targeting 
locations with the highest risk; (2) a plant-based approach can result 
in disproportionate monitoring requirements for systems serving the 
same number of people (due to widely varying numbers of plants per 
system); (3) it cannot be adequately applied to plants or consecutive 
system entry points that are operated seasonally or intermittently if 
an LRAA is used for compliance due to complex implementation and a need 
for repeated transactions between the State and

[[Page 429]]

system to determine whether and how compliance monitoring requirements 
may need to be changed; (4) State determinations of monitoring 
requirements for consecutive systems would be complicated, especially 
in large combined distribution systems with many connections between 
systems; and (5) systems with multiple disinfecting wells would have to 
conduct evaluation of common aquifers in order to avoid taking 
unnecessary samples for compliance (if they did not conduct such 
evaluations under Stage 1). EPA requested comment on two approaches to 
address these issues: (1) keep the plant-based monitoring approach and 
add new provisions to address specific concerns; and (2) base 
monitoring requirements on source water type and population served, in 
lieu of plant-based monitoring.
    The final rule's requirements of population-based monitoring for 
all systems are based on improved public health protection, 
flexibility, and simplified implementation. For determining monitoring 
requirements, EPA's objective was to maintain monitoring loads 
consistent with Stage 1 and similar to monitoring loads proposed for 
Stage 2 under a plant-based approach, using a population-based approach 
to facilitate implementation, better target high DBP levels, and 
protect human health. This leads to a more cost-effective 
characterization of where high levels occur. For the proposed rule, EPA 
used 1995 CWSS data to derive the number of plants per system for 
calculating the number of proposed monitoring sites per system. During 
the comment period, 2000 CWSS data became available. Compared to the 
1995 CWSS, the 2000 CWSS contained questions more relevant for 
determining the number of plants in each system. Based on 2000 CWSS 
data, EPA has modified the number of monitoring sites per system for 
several categories (particularly for the larger subpart H systems) to 
align the median population-based monitoring requirements with the 
median monitoring requirements under plant-based monitoring, as was 
proposed.
    EPA also believes that more samples are necessary to characterize 
larger systems (as defined by population) than for smaller systems. 
This progressive approach is included in Table IV.G-4. As system size 
increases, the number of samples increases to better reflect the 
hydraulic complexity of these systems. While the national monitoring 
burden under the population-based approach is slightly less than under 
a plant-based approach, some larger systems with few plants relative to 
system population will take more samples per system than they had under 
plant-based monitoring. However, EPA believes that many of these large 
systems with few plants have traditionally been undermonitored (as 
noted in the proposal). Systems with more plants will see a reduction 
in monitoring (e.g., small ground water systems with multiple wells).
    While population-based monitoring requirements for ground water 
systems in today's rule remain the same as those in the proposed rule, 
the final rule consolidates ten population categories for subpart H 
systems into eight categories for ease of implementation. As indicated 
in Table IV.G-4, EPA has gone from four to three population size 
categories for smaller subpart H systems (serving fewer than 10,000 
people) and the ranges have been modified to be consistent with those 
for other existing rules (such as the Lead and Copper Rule). This 
change will reduce implementation transactional costs. For medium and 
large subpart H systems (serving at least 10,000 people), EPA has gone 
from seven categories in the proposal to five categories in final rule. 
The population groups are sized so that the ratio of maximum population 
to minimum population for each of the categories is consistent. EPA 
believes that this will allow most systems to remain in one population 
size category and maintain the same monitoring requirements within a 
reasonable range of population variation over time. In addition, it 
assures that systems within a size category will not have disparate 
monitoring burdens as could occur if there were too few categories. 
Overall, EPA believes that the population-based monitoring approach 
allows systems to have more flexibility to designate their monitoring 
sites within the distribution system to better target high DBP levels 
and is more equitable.
    To derive the number of monitoring sites for IDSE standard 
monitoring, EPA doubled the number of routine compliance monitoring 
sites per system for each size category. This is consistent with the 
advice and recommendations of the M-DBP Advisory Committee for the 
IDSE. EPA has developed the Initial Distribution System Evaluation 
Guidance Manual for the Final Stage 2 Disinfectants and Disinfection 
Byproducts Rule (USEPA 2006) to assist systems in choosing IDSE 
monitoring locations, including criteria for selecting monitoring.

 Table IV.G-4.--Comparison of Monitoring Locations per System for Stage 2 Routine Compliance Monitoring with Plant-Based and Population-Based Approaches
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                            Plant-based    Number of plants per      Calculated number of
                                                                             approach*     system (Based on 2000     sites per system for
                                                    Ratio of               -------------        CWSS data)           plant-based approach     Number of
                                                    maximum     Number of               ----------------------------------------------------  monitoring
               Population category                 population    sampling                                            Based on     Based on    sites per
                                                   to minimum  periods per                                   median    mean     i> plants    pop-based
                                                                               plant                                plants per   per system    approach
                                                                                                                      system
                                                  ...........            A            B            C            D        E=B*C        F=B*D            G
-------------------------------------------------
<500............................................  ...........            1          **1            1         1.21            1          1.2          **1
500-3,300.......................................          6.6            4          **1            1         1.22            1          1.2          **1
3,301-9,999.....................................            3            4            2            1         1.56            2          3.1            2
10,000-49,999...................................            5            4            4            1         1.37            4          5.5            4
50,000-249,999..................................            5            4            4            1         1.83            4          7.3            8
250,000-<1 million..............................            4            4            4            2         2.53            8         10.1           12
1 million-<5 million............................            5            4            4            4         3.62           16         14.5           16
>=5 million.....................................  ...........            4            4            4         4.33           16         17.3          20
--------------------------------------------------------------------------------------------------------------------------------------------------------
* As in the proposal.
** System is required to take individual TTHM and HAA5 samples at the locations with the highest TTHM and HAA5 concentrations, respectively, if highest
  TTHM and HAA5 concentrations do not occur at the same location.

[[Page 430]]

 
Note: To determine the number of routine compliance monitoring sites per population category, EPA took these steps: (1) Maintaining about the same
  sampling loads in the nation as required under the plant-based approach, but basing on population rather than number of plants to better target high
  DBP levels in distribution systems and facilitate implementation; (2) The number of monitoring sites per plant under the plant-based approach (Column
  B) were multiplied by the number of plants per system (Columns C and D) to calculate the number of monitoring sites per system under the plant-based
  approach (Columns E and F in terms of median and mean, respectively); and (3) The number of monitoring sites per system under the population-based
  approach were derived with adjustments to keep categories consistent and to maintain an even incremental trend as the population size category
  increases (Column G).

3. Summary of Major Comments
    EPA received significant support for applying the population-based 
approach to all systems. EPA also received comments concerning the 
specific requirements in a population-based approach.
    Excessive Sampling Requirements. Several commenters believed that 
the proposed sampling requirements were excessive (especially in the 
larger population categories for subpart H systems) and that some 
individual systems would be required to sample more under the 
population-based approach than the plant-based approach. EPA recognizes 
that a small fraction of systems in some categories will have to take 
more samples under the population-based approach than the plant-based 
approach because their number of plants is substantially less than the 
national median or mean. However, the number of samples required under 
the Stage 1 DBPR for these systems may not have been sufficient to 
determine the concentrations of DBPs throughout the distribution system 
of these systems. On the other hand, systems with many plants may have 
taken excessive samples under the Stage 1 DBPR that were not necessary 
to appropriately determine DBP levels throughout the distribution 
system. Consequently, the total number of samples taken nationally will 
be comparable to the Stage 1 DBPR, but will better target DBP risks in 
individual distribution systems.
    Consecutive systems. Some commenters noted that a consecutive 
system may need to take more samples than its associated wholesale 
system. Under today's rule, all systems, including consecutive systems, 
must monitor based on retail population served. Thus, large consecutive 
systems will take more samples than a smaller wholesale system. The 
population-based monitoring approach will allow the samples to better 
represent the DBP concentrations consumed by the population associated 
with the sampling locations and to understand the DBP concentrations 
reaching consumers. There is also a provision that allows States to 
specify alternative monitoring requirements for a consecutive system in 
a combined distribution system (40 CFR 142.16(m)(3)). This special 
primacy condition allows the State to establish monitoring requirements 
that account for complicated distribution system relationships, such as 
where neighboring systems buy from and sell to each other regularly 
throughout the year. In this case, water may pass through multiple 
consecutive systems before it reaches a user. Another example would be 
a large group of interconnected systems that have a complicated 
combined distribution system. This approach also allows the combined 
distribution system to concentrate IDSE and Stage 2 monitoring sites in 
the system with the highest known DBP concentrations, while assigning 
fewer sample sites to systems with low DBP concentrations.
    Population Size Categories. Some commenters recommended fewer 
population categories for subpart H systems (those using surface water 
or ground water under the direct influence of surface water as a 
source) than proposed while others recommended more. Today's rule has 
fewer categories than proposed. However, EPA believes that further 
reduction of the number of population size categories will not reflect 
the fact that the number of plants and complexity of distribution 
systems (and DBP exposure) tend to increase as the population served 
increases. As a result, the population served by a large system in one 
particular category would receive much less protection from the DBP 
risks than a smaller system in the same size category. On the other 
hand, too many categories with smaller population ranges would result 
in frequent category and requirement shifts as population fluctuates. 
Much greater implementation effort would be needed for those systems 
without much benefit in DBP exposure knowledge.
    Population Definition. Some commenters supported use of the 
population of a combined distribution system (i.e., the wholesale and 
consecutive systems should be considered a single system for monitoring 
purposes) while others preferred use of the retail population for each 
individual system (i.e., wholesale systems and consecutive systems are 
considered separately). Today's final rule uses the retail population 
for each individual system. EPA chose this approach for today's rule 
because of the complexity involved in making implementation decisions 
for consecutive systems. Using the retail population to determine 
requirements eases the complexity by specifying minimum system-level 
requirements; simplicity is essential for meeting the implementation 
schedule in today's rule. If monitoring requirements were determined by 
the combined distribution system population, many implementation 
problems would occur. Some of these problems would have the potential 
to impact public health protection. For example, States or primacy 
agencies would have to decide how to allocate IDSE distribution system 
samples (where and how much to monitor in individual PWSs) in a 
complicated combined distribution system with many systems, multiple 
sources, multiple treatment plants, and varying water demand and with 
limited understanding of DBP levels throughout the combined 
distribution system. This would have to happen shortly after rule 
promulgation in order to meet the schedule. For example, some 
consecutive systems buy water seasonally (in times of high water 
demand) or buy from more than one wholesale system (with the volume 
purchased based on many factors). The State or primacy agency would 
find it difficult to properly assign a limited number of IDSE 
monitoring locations (especially since there are States where many 
consecutive systems have no DBP data) to adequately reflect DBP levels 
in such a system, as well as throughout the combined distribution 
system.
    EPA believes that assigning compliance monitoring requirements 
appropriately throughout the combined distribution system requires a 
case-by-case determination based on factors such as amount and 
percentage of finished water provided; whether finished water is 
provided seasonally, intermittently, or full-time; and improved DBP 
occurrence information. Since the IDSE will provide improved DBP 
occurrence information throughout the combined distribution system, 
States may consider modifications to Stage 2 compliance monitoring 
requirements for consecutive systems on a case-by-case basis as allowed 
by Sec.  141.29 or under the special primacy condition at Sec.  
142.16(m)(3) by taking all these factors into consideration. In making 
these case-by-case determinations, the State will be able to use its 
system-specific knowledge, along with the IDSE results, to develop an 
appropriate monitoring plan for each

[[Page 431]]

system within the combined distribution system.
    Changes to monitoring plans. Commenters requested more specific 
language regarding how IDSE and Stage 2 monitoring plans should be 
updated as a result of treatment or population changes in the 
distribution system. Changes to IDSE plans should not be necessary 
since the State or primacy agency will have reviewed those plans 
shortly before the system must conduct the IDSE and the reviewed plan 
should identify such issues. EPA provided a process in the Stage 2 DBPR 
proposal for updating monitoring plans for systems that have 
significant changes to treatment or in the distribution system after 
they complete their IDSE. This process remains in today's rule, with an 
added requirement that systems must consult with the State or primacy 
agency to determine whether the changes are necessary and appropriate 
prior to implementing changes to their Stage 2 monitoring plan.
    In addition, the State or primacy agency may require a system to 
revise its IDSE plan, IDSE report, or Stage 2 monitoring plan at any 
time. This change was made so that systems could receive system-
specific guidance from the State or primacy agency on the appropriate 
revisions to the Stage 2 monitoring plan. Regulatory language regarding 
changes that might occur is not appropriate because any modifications 
would be system-specific and a national requirement is not capable of 
addressing these system-specific issues.

H. Operational Evaluation Requirements Initiated by TTHM and HAA5 
Levels

    A system that is in full compliance with the Stage 2 DBPR LRAA MCL 
may still have individual DBP measurements that exceed the Stage 2 DBPR 
MCLs, since compliance is based on individual DBP measurements at a 
location averaged over a four-quarter period. EPA and the Advisory 
Committee were concerned about these higher levels of DBPs. This 
concern was clearly reflected in the Agreement in Principle, which 
states, ``. . . significant excursions of DBP levels will sometimes 
occur, even when systems are in full compliance with the enforceable 
MCL. . .''.
    Today's final rule addresses this concern by requiring systems to 
conduct operational evaluations that are initiated by operational 
evaluation levels identified in Stage 2 DBPR compliance monitoring and 
to submit an operational evaluation report to the State.
1. Today's Rule
    Today's rule defines the Stage 2 DBP operational evaluation levels 
that require systems to conduct operational evaluations. The Stage 2 
DBP operational evaluation levels are identified using the system's 
Stage 2 DBPR compliance monitoring results. The operational evaluation 
levels for each monitoring location are determined by the sum of the 
two previous quarters' TTHM results plus twice the current quarter's 
TTHM result, at that location, divided by 4 to determine an average and 
the sum of the two previous quarters' HAA5 results plus twice the 
current quarter's HAA5 result, at that location, divided by 4 to 
determine an average. If the average TTHM exceeds 0.080 mg/L at any 
monitoring location or the average HAA5 exceeds 0.060 mg/L at any 
monitoring location, the system must conduct an operational evaluation 
and submit a written report of the operational evaluation to the State.
    Operational evaluation levels (calculated at each monitoring 
location)
    IF (Q1 + Q2 + 2Q3)/4> MCL, then 
the system must conduct an operational evaluation

where:

    Q3 = current quarter measurement
    Q2 = previoius quarter measurement
    Q1 = quarter before previous quarter measurement

    MCL = Stage 2 MCL for TTHM (0.080 mg/l) or Stage 2 MCL for HAA5 
(0.060 mg/L)
    The operational evaluation includes an examination of system 
treatment and distribution operational practices, including changes in 
sources or source water quality, storage tank operations, and excess 
storage capacity, that may contribute to high TTHM and HAA5 formation. 
Systems must also identify what steps could be considered to minimize 
future operational evaluation level exceedences. In cases where the 
system can identify the cause of DBP levels that resulted in the 
operational evaluation, based on factors such as water quality data, 
plant performance data, and distribution system configuration the 
system may request and the State may allow limiting the evaluation to 
the identified cause. The State must issue a written determination 
approving limiting the scope of the operational evaluation. The system 
must submit their operational evaluation report to the State for review 
within 90 days after being notified of the analytical result that 
initiates the operational evaluation. Requesting approval to limit the 
scope of the operational evaluation does not extend the schedule (90 
days after notification of the analytical result) for submitting the 
operational evaluation report.

2. Background and Analysis

    The Stage 2 DBPR proposal outlined three components of the 
requirements for significant excursions (definition, system evaluation 
and excursion report). In response to public comments, the term 
``significant excursion'' has been replaced by the term ``operational 
evaluation level'' in today's rule. The evaluation and report 
components remain the same as those outlined in the proposed rule for 
significant excursions. However, the scope of the evaluation and report 
components of the operational evaluation has also been modified from 
the proposed significant excursion evaluation components based on 
public comments.
    In the Stage 2 DBPR proposal, States were to define criteria to 
identify significant excursions rather than using criteria defined by 
EPA. Concurrent with the Stage 2 DBPR proposal, EPA issued draft 
guidance (USEPA 2003e) for systems and States that described how to 
determine whether a significant excursion has occurred, using several 
different options. The rule proposal specifically requested public 
comment on the definition of a significant excursion, whether it should 
be defined by the State or nationally, and the scope of the evaluation.
    After reviewing comments on the Stage 2 DBPR proposal, EPA 
determined that DBP levels initiating an operational evaluation should 
be defined in the regulation to ensure national consistency. Systems 
were concerned with the evaluation requirements being initiated based 
on criteria that might not be consistent nationally. Also, many States 
believed the requirement for States to define criteria to initiate an 
evaluation would be difficult for States to implement.
    Under today's rule, EPA is defining operational evaluation levels 
with an algorithm based on Stage 2 DBPR compliance monitoring results. 
These operational evaluation levels will act as an early warning for a 
possible MCL violation in the following quarter. This early warning is 
accomplished because the operational evaluation requirement is 
initiated when the system assumes that the current quarter's result is 
repeated and this will result in an MCL violation. This early 
identification allows the system to act to prevent the violation.
    Today's rule also modifies the scope of an operational evaluation. 
EPA has concluded that the source of DBP levels

[[Page 432]]

that would initiate an operational evaluation can potentially be linked 
to a number of factors that extend beyond distribution system 
operations. Therefore, EPA believes that evaluations must include a 
consideration of treatment plant and other system operations rather 
than limiting the operational evaluation to only the distribution 
system, as proposed. Because the source of the problem could be 
associated with operations in any of these system components (or more 
than one), an evaluation that provides systems with valuable 
information to evaluate possible modifications to current operational 
practices (e.g. water age management, source blending) or in planning 
system modifications or improvements (e.g. disinfection practices, tank 
modifications, distribution looping) will reduce DBP levels initiating 
an operational evaluation. EPA also believes that State review of 
operational evaluation reports is valuable for both States and systems 
in their interactions, particularly when systems may be in discussions 
with or requesting approvals from the State for system improvements. 
Timely reviews of operational evaluation reports will be valuable for 
States in reviewing other compliance submittals and will be 
particularly valuable in reviewing and approving any proposed source, 
treatment or distribution system modifications for a water system. 
Under today's rule, systems must submit a written report of the 
operational evaluation to the State no later than 90 days after being 
notified of the DBP analytical result initiating an operational 
evaluation. The written operational evaluation report must also be made 
available to the public upon request.
3. Summary of Major Comments
    EPA received comments both in favor of and opposed to the proposed 
evaluation requirements. While some commenters felt that the evaluation 
requirements should not be a part of the Stage 2 DBPR until there was 
more information regarding potential health effects correlated to 
specific DBP levels, other commenters felt that the existing health 
effects data were sufficient to warrant strengthening the proposed 
requirements for an evaluation. Today's final rule requirements are 
consistent with the Agreement in Principle recommendations.
    Some commenters noted that health effects research on DBPs is 
insufficient to identify a level at which health effects occur and were 
concerned that the proposed significant excursion requirements placed 
an emphasis on DBP levels that might not be warranted rather than on 
system operational issues and compliance with Stage 2 DBPR MCLs.
    Basis. The proposed requirements for significant excursion 
evaluations were not based upon health effects, but rather were 
intended to be an indicator of operational performance. To address 
commenter's concerns and to emphasize what EPA believes should initiate 
a comprehensive evaluation of system operations that may result in 
elevated DBP levels and provide a proactive procedure to address 
compliance with Stage 2 DBP LRAA MCLs , EPA has replaced the term 
``significant excursion'' used in the Stage 2 DBPR proposal with the 
term ``operational evaluation level'' in today's rule.
    Definition of the operational evaluation levels. The majority of 
commenters stated that EPA should define the DBP levels initiating an 
operational evaluation (``significant excursion'' in the proposal) in 
the regulation to ensure national consistency rather than requiring 
States to develop their own criteria (as was proposed). Commenters 
suggested several definitions, including a single numerical limit and 
calculations comparing previous quarterly DBP results to the current 
quarter's result. Commenters that recommended a single numerical limit 
felt that such an approach was justified by the available health 
effects information, while other commenters felt available heath 
effects information did not support a single numerical limit. 
Commenters recommended that any definition be easy to understand and 
implement.
    EPA agrees with commenter preference for national criteria to 
initiate an operational evaluation. The DBP levels initiating an 
operational evaluation in today's rule consider routine operational 
variations in distribution systems, are simple for water systems to 
calculate, and minimize the implementation burden on States. They also 
provide an early warning to help identify possible future MCL 
violations and allow the system to take proactive steps to remain in 
compliance. EPA emphasizes, as it did in the proposal and elsewhere in 
this notice, that health effects research is insufficient to identify a 
level at which health effects occur, and thus today's methodology for 
initiating operational evaluation is not based upon health effects, but 
rather is intended as an indicator of operational performance.
    Scope of an evaluation. Some commenters felt that the scope of an 
evaluation initiated by locational DBP levels should be limited to the 
distribution systems, as in the proposal. Others felt that the 
treatment processes should be included in the evaluation, noting that 
these can be significant in the formation of DBPs.
    The Agency agrees with commenters that treatment processes can be a 
significant factor in DBP levels initiating an operational evaluation 
and that a comprehensive operational evaluation should address 
treatment processes. In cases where the system can clearly identify the 
cause of the DBP levels initiating an operational evaluation (based on 
factors such as water quality data, plant performance data, 
distribution system configuration, and previous evaluations) the State 
may allow the system to limit the scope of the evaluation to the 
identified cause. In other cases, it is appropriate to evaluate the 
entire system, from source through treatment to distribution system 
configuration and operational practices.
    Timing for completion and review of the evaluation report. While 
some commenters agreed that the evaluation report should be reviewed as 
part of the sanitary survey process (as proposed), many commenters felt 
that the time between sanitary surveys (up to five years) minimized the 
value of the evaluation report in identifying both the causes of DBP 
levels initiating an operational evaluation and in possible changes to 
prevent recurrence. Moreover, a number of commenters felt that the 
evaluation report was important enough to warrant a separate submittal 
and State review rather than have the evaluation report compete with 
other priorities during a sanitary survey.
    The Agency agrees that completion and State review of evaluation 
reports on a three or five year sanitary survey cycle, when the focus 
of the evaluation is on what may happen in the next quarter, would 
allow for an unreasonable period of time to pass between the event 
initiating the operational evaluation and completion and State review 
of the report. This would diminish the value of the evaluation report 
for both systems and States, particularly when systems may be in 
discussions with or requesting approval for treatment changes from 
States, and as noted above, the focus of the report is on what may 
occur in the next quarter. EPA believes that timely reviews of 
evaluation reports by States is important, would be essential for 
States in understanding system operations and reviewing other 
compliance submittals, and would be extremely valuable in reviewing and 
approving any proposed source, treatment or distribution system 
modifications for a water system.

[[Page 433]]

Having the evaluation information on an ongoing basis rather than a 
delayed basis would also allow States to prioritize their resources in 
scheduling and reviewing particular water system operations and 
conditions as part of any on-site system review or oversight. 
Therefore, today's rule requires that systems complete the operational 
evaluation and submit the evaluation report to the State within 90 days 
of the occurrence.

I. MCL, BAT, and Monitoring for Bromate

1. Today's Rule
    Today EPA is confirming that the MCL for bromate for systems using 
ozone remains at 0.010 mg/L as an RAA for samples taken at the entrance 
to the distribution system as established by the Stage 1 DBPR. Because 
the MCL remains the same, EPA is not modifying the existing bromate 
BAT. EPA is changing the criterion for a system using ozone to qualify 
for reduced bromate monitoring from demonstrating low levels of bromide 
to demonstrating low levels of bromate.
2. Background and Analysis
    a. Bromate MCL. Bromate is a principal byproduct from ozonation of 
bromide-containing source waters. As described in more detail in the 
Stage 2 DBPR proposal (USEPA 2003a), more stringent bromate MCL has the 
potential to decrease current levels of microbial protection, impair 
the ability of systems to control resistant pathogens like 
Cryptosporidium, and increase levels of DBPs from other disinfectants 
that may be used instead of ozone. EPA considered reducing the bromate 
MCL from 0.010 mg/L to 0.005 mg/L as an annual average but concluded 
that many systems using ozone to inactivate microbial pathogens would 
have significant difficulty maintaining bromate levels at or below 
0.005 mg/L. In addition, because of the high doses required, the 
ability of systems to use ozone to meet Cryptosporidium treatment 
requirements under the LT2ESWTR would be diminished if the bromate MCL 
was decreased from 0.010 to 0.005 mg/L; higher doses will generally 
lead to greater bromate formation. After evaluation under the risk-
balancing provisions of section 1412(b)(5) of the SDWA, EPA concluded 
that the existing MCL was justified. EPA will review the bromate MCL as 
part of the six-year review process and determine whether the MCL 
should remain at 0.010 mg/L or be reduced to a lower level. As a part 
of that review, EPA will consider the increased utilization of 
alternative technologies, such as UV, and whether the risk/risk 
concerns reflected in today's rule, as well as in the LT2ESWTR, remain 
valid.
    b. Criterion for reduced bromate monitoring. Because more sensitive 
bromate methods are now available, EPA is requiring a new criterion for 
reduced bromate monitoring. In the Stage 1 DBPR, EPA required ozone 
systems to demonstrate that source water bromide levels, as a running 
annual average, did not exceed 0.05 mg/L. EPA elected to use bromide as 
a surrogate for bromate in determining eligibility for reduced 
monitoring because the available analytical method for bromate was not 
sensitive enough to quantify levels well below the bromate MCL of 0.010 
mg/L.
    EPA approved several new analytical methods for bromate that are 
far more sensitive than the existing method as part of today's rule. 
Since these methods can measure bromate to levels of 0.001 mg/L or 
lower, EPA is replacing the criterion for reduced bromate monitoring 
(source water bromide running annual average not to exceed 0.05 mg/L) 
with a bromate running annual average not to exceed 0.0025 mg/L.
    In the past, EPA has often set the criterion for reduced monitoring 
eligibility at 50% of the MCL, which would be 0.005 mg/L. However, the 
MCL for bromate will remain at 0.010 mg/L, representing a risk level of 
2x10/b 2x10-4, 10-4 and 10-6 (higher 
than EPA's usual excess cancer risk range of 10-4 to 
10-6) because of risk tradeoff considerations) (USEPA 
2003a).
    EPA believes that the decision for reduced monitoring is separate 
from these risk tradeoff considerations. Risk tradeoff considerations 
influence the selection of the MCL, while reduced monitoring 
requirements are designed to ensure that the MCL, once established, is 
reliably and consistently achieved. Requiring a running annual average 
of 0.0025 mg/L for the reduced monitoring criterion allows greater 
confidence that the system is achieving the MCL and thus ensuring 
public health protection.
3. Summary of Major Comments
    Commenters supported both the retention of the existing bromate MCL 
and the modified reduced monitoring criterion.

J. Public Notice Requirements

1. Today's Rule
    Today's rule does not alter existing public notification language 
for TTHM, HAA5 or TOC, which are listed under 40 CFR 141.201-141.210 
(Subpart Q).
2. Background and Analysis
    EPA requested comment on including language in the proposed rule 
concerning potential reproductive and developmental health effects. EPA 
believes this is an important issue because of the large population 
exposed (58 million women of child-bearing age; USEPA 2005a) and the 
number of studies that, while not conclusive, point towards a potential 
risk concern. While EPA is not including information about reproductive 
and developmental health effects in public notices at this time, the 
Agency plans to reconsider whether to include this information in the 
future. As part of this effort, EPA intends to support research to 
assess communication strategies on how to best provide this 
information.
    The responsibilities for public notification and consumer 
confidence reports rest with the individual system. Under the Public 
Notice Rule (Part 141 subpart Q) and Consumer Confidence Report Rule 
(Part 141 subpart O), the wholesale system is responsible for notifying 
the consecutive system of analytical results and violations related to 
monitoring conducted by the wholesale system. Consecutive systems are 
required to conduct appropriate public notification after a violation 
(whether in the wholesale system or the consecutive system). In their 
consumer confidence report, consecutive systems must include results of 
the testing conducted by the wholesale system unless the consecutive 
system conducted equivalent testing (as required in today's rule) that 
indicated the consecutive system was in compliance, in which case the 
consecutive system reports its own compliance monitoring results.
3. Summary of Major Comments
    EPA requested and received many comments on the topic of including 
public notification language regarding potential reproductive and 
developmental effects. A number of comments called for including 
reproductive and developmental health effects language to address the 
potential health concerns that research has shown. Numerous comments 
also opposed such language due to uncertainties in the underlying 
science and the implications such language could have on public trust 
of utilities.
    EPA agrees on the importance of addressing possible reproductive 
and developmental health risks. However, given the uncertainties in the 
science and our lack of knowledge of how to best communicate undefined 
risks, a general statement about reproductive

[[Page 434]]

and developmental health effects is premature at this time. The Agency 
needs to understand how best to characterize and communicate these 
risks and what to do to follow up any such communication. The public 
deserves accurate, timely, relevant, and understandable communication. 
The Agency will continue to follow up on this issue with additional 
research, possibly including a project to work with stakeholders to 
assess risk communication strategies.
    Some comments also suggested leaving the choice of language up to 
the water server. EPA believes that this strategy would cause undue 
confusion to both the PWS and the public.
    Commenters generally agreed that both wholesale and consecutive 
systems that conduct monitoring be required to report their own 
analytical results as part of their CCRs. One commenter requested 
clarification of consecutive system public notification requirements 
when there is a violation in the wholesale system but the consecutive 
system data indicate that it meets DBP MCLs.
    Although EPA requires consecutive systems to conduct appropriate 
public notification of violations (whether in the wholesale or 
consecutive system), there may be cases where the violation may only 
affect an isolated portion of the distribution system. Under the public 
notification rule, the State may allow systems to limit distribution of 
the notice to the area that is out of compliance if the system can 
demonstrate that the violation occurred in a part of the distribution 
system that is ``physically or hydraulically isolated from other parts 
of the distribution system.'' This provision remains in place. As for a 
consecutive system whose wholesale system is in violation, the 
consecutive system is not required to conduct public notification if 
DBP levels in the consecutive system are in compliance.

K. Variances and Exemptions

1. Today's Rule
    States may grant variances in accordance with sections 1415(a) and 
1415(e) of the SDWA and EPA's regulations. States may grant exemptions 
in accordance with section 1416(a) of the SDWA and EPA's regulations.
2. Background and Analysis
    a. Variances. The SDWA provides for two types of variances--general 
variances and small system variances. Under section 1415(a)(1)(A) of 
the SDWA, a State that has primary enforcement responsibility 
(primacy), or EPA as the primacy agency, may grant general variances 
from MCLs to those public water systems of any size that cannot comply 
with the MCLs because of characteristics of the raw water sources. The 
primacy agency may grant general variances to a system on condition 
that the system install the best technology, treatment techniques, or 
other means that EPA finds available and based upon an evaluation 
satisfactory to the State that indicates that alternative sources of 
water are not reasonably available to the system. At the time this type 
of variance is granted, the State must prescribe a compliance schedule 
and may require the system to implement additional control measures. 
Furthermore, before EPA or the State may grant a general variance, it 
must find that the variance will not result in an unreasonable risk to 
health (URTH) to the public served by the public water system. In 
today's final rule, EPA is specifying BATs for general variances under 
section 1415(a) (see section IV.D).
    Section 1415(e) authorizes the primacy agency to issue variances to 
small public water systems (those serving fewer than 10,000 people) 
where the primacy agent determines (1) that the system cannot afford to 
comply with an MCL or treatment technique and (2) that the terms of the 
variances will ensure adequate protection of human health (63 FR 43833, 
August 14, 1998) (USEPA 1998c). These variances may only be granted 
where EPA has determined that there is no affordable compliance 
technology and has identified a small system variance technology under 
section 1412(b)(15) for the contaminant, system size and source water 
quality in question. As discussed below, small system variances under 
section 1415(e) are not available because EPA has determined that 
affordable compliance technologies are available.
    The 1996 Amendments to the SDWA identify three categories of small 
public water systems that need to be addressed: (1) Those serving a 
population of 3301-10,000; (2) those serving a population of 500-3300; 
and (3) those serving a population of 25-499. The SDWA requires EPA to 
make determinations of available compliance technologies for each size 
category. A compliance technology is a technology that is affordable 
and that achieves compliance with the MCL and/or treatment technique. 
Compliance technologies can include point-of-entry or point-of-use 
treatment units. Variance technologies are only specified for those 
system size/source water quality combinations for which there are no 
listed affordable compliance technologies.
    Using its current National Affordability Criteria, EPA has 
determined that multiple affordable compliance technologies are 
available for each of the three system sizes (USEPA 2005a), and 
therefore did not identify any variance treatment technologies. The 
analysis was consistent with the current methodology used in the 
document ``National-Level Affordability Criteria Under the 1996 
Amendments to the Safe Drinking Water Act'' (USEPA 1998d) and the 
``Variance Technology Findings for Contaminants Regulated Before 1996'' 
(USEPA 1998e). However, EPA is currently reevaluating its national-
level affordability criteria and has solicited recommendations from 
both the NDWAC and the SAB as part of this review. EPA intends to apply 
the revised criteria to the Stage 2 DBPR once they have been finalized 
for the purpose of determining whether to enable States to give 
variances. Thus, while the analysis of Stage 2 household costs will not 
change, EPA's determination regarding the availability of affordable 
compliance technologies for the different categories of small systems 
may.
    b. Affordable Treatment Technologies for Small Systems. The 
treatment trains considered and predicted to be used in EPA's 
compliance forecast for systems serving under 10,000 people, are listed 
in Table IV.K-1.

   Table IV.K-1.--Technologies Considered and Predicted To Be Used in
                  Compliance Forecast for Small Systems
------------------------------------------------------------------------
            SW Water Plants                      GW Water Plants
------------------------------------------------------------------------
 Switching to chloramines as a    Switching to
 residual disinfectant.                   chloramines as a residual
                                          disinfectant
 Chlorine dioxide (not for        UV
 systems serving fewer than 100 people).
 UV............................   Ozone (not for systems
                                          serving fewer than 100 people)
 Ozone (not for systems serving   GAC20
 fewer than 100 people).
 Micro-filtration/Ultra-          Nanofiltration
 filtration.

[[Page 435]]

 
 GAC20.........................
 GAC20 + Advanced disinfectants
 Integrated Membranes..........
------------------------------------------------------------------------
Note: Italicized technologies are those predicted to be used in the
  compliance forecast.
 
Source: Exhibits 5.11b and 5.14b, USEPA 2005a.

    The household costs for these technologies were compared against 
the EPA's current national-level affordability criteria to determine 
the affordable treatment technologies. The Agency's national level 
affordability criteria were published in the August 6, 1998 Federal 
Register (USEPA 1998d). A complete description of how this analysis was 
applied to Stage 2 DBPR is given in Section 8.3 of the Economic 
Analysis (USEPA 2005a).
    Of the technologies listed in Table IV.K-1, integrated membranes 
with chloramines, GAC20 with advanced oxidants, and ozone are above the 
affordability threshold in the 0 to 500 category. No treatment 
technologies are above the affordability threshold in the 500 to 3,300 
category or the 3,300 to 10,000 category. As shown in the Economic 
Analysis for systems serving fewer than 500 people, 14 systems are 
predicted to use GAC20 with advanced disinfectants, one system is 
predicted to use integrated membranes, and no systems are predicted to 
use ozone to comply with the Stage 2 DBPR (USEPA 2005a). However, 
several alternate technologies are affordable and likely available to 
these systems. In some cases, the compliance data for these systems 
under the Stage 2 DBPR will be the same as under the Stage 1 DBPR 
(because many systems serving fewer than 500 people will have the same 
single sampling site under both rules); these systems will have already 
installed the necessary compliance technology to comply with the Stage 
1 DBPR. It is also possible that less costly technologies such as those 
for which percentage use caps were set in the decision tree may 
actually be used to achieve compliance (e.g., chloramines, UV). Thus, 
EPA believes that compliance by these systems will be affordable.
    As shown in Table IV.K-2, the cost model predicts that some 
households served by very small systems will experience household cost 
increases greater than the available expenditure margins as a result of 
adding advanced technology for the Stage 2 DBPR (USEPA 2005a). This 
prediction may be overestimated because small systems may have other 
compliance alternatives available to them besides adding treatment, 
which were not considered in the model. For example, some of these 
systems currently may be operated on a part-time basis; therefore, they 
may be able to modify the current operational schedule or use excessive 
capacity to avoid installing a costly technology to comply with the 
Stage 2 DBPR. The system also may identify another water source that 
has lower TTHM and HAA5 precursor levels. Systems that can identify 
such an alternate water source may not have to treat that new source 
water as intensely as their current source, resulting in lower 
treatment costs. Systems may elect to connect to a neighboring water 
system. While connecting to another system may not be feasible for some 
remote systems, EPA estimates that more than 22 percent of all small 
water systems are located within metropolitan regions (USEPA 2000f) 
where distances between neighboring systems will not present a 
prohibitive barrier. Low-cost alternatives to reduce total 
trihalomethanes (TTHM) and haloacetic acid (HAA5) levels also include 
distribution system modifications such as flushing distribution mains 
more frequently, looping to prevent dead ends, and optimizing storage 
to minimize retention time. More discussion of household cost increases 
is presented in Section VI.E and the Economic Analysis (USEPA 2005a).

                                                    Table IV.K-2.--Distribution of Household Unit Treatment Costs for Plants Adding Treatment
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Number of
                                                                 households                                                                    Number of    Number of    Number of      Total
                                                                 served by                                                                     households    surface    groundwater   number of
                                                                   plants                                  90th         95th                  with annual     water     plants with  plants with
                                                                   adding    Mean annual     Median     Percentile   Percentile   Available       cost     plants with  annual cost  annual cost
                                                                 treatment    household      annual       annual       annual    expenditure   increases   annual cost   increases    increases
                Systems size (population seved)                 (Percent of      cost      household    household    household    margin ($/    greater     increases     greater      greater
                                                                    all        increase       cost         cost         cost        hh/yr)      than the     greater      than the     than the
                                                                 households                 increase     increase     increase                 available     than the    available    available
                                                                 subject to                                                                   expenditure   available   expenditure  expenditure
                                                                the Stage 2                                                                      margin    expenditure     margin       margin
                                                                   DBPR)                                                                                      margin
                                                                          A            B            C            D            E            F            G            H            I    J = H + I
---------------------------------------------------------------
0-500.........................................................     43045(3)      $201.55      $299.01      $299.01      $414.74         $733          964           15            0           15
501-3,300.....................................................   205842 (4)       $58.41       $29.96       $75.09      $366.53         $724            0            9            0            0
3,301-10,000..................................................   342525 (5)       $37.05       $14.59       $55.25      $200.05         $750            0            0            0            0
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: Household unit costs represent treatment costs only. All values in year 2003 dollars.
 
Source: Exhibit 8.4c, USEPA 2005a.

    c. Exemptions. Under section 1416(a), EPA or a State that has 
primary enforcement responsibility (primacy) may exempt a public water 
system from any requirements related to an MCL or treatment technique 
of an NPDWR, if it finds that (1) due to compelling factors (which may 
include economic factors such as qualification of the PWS as serving a 
disadvantaged community), the PWS is unable to comply with the 
requirement or implement measures to develop an alternative source of 
water supply; (2) the exemption will not result in an unreasonable risk 
to health; and; (3) the PWS was in operation on the effective date of 
the NPDWR, or for a system that was not in operation by that date, only 
if no reasonable alternative source of drinking water is available to 
the new system; and (4) management or restructuring changes (or both) 
cannot reasonably result in compliance with the Act or improve the 
quality of

[[Page 436]]

drinking water. If EPA or the State grants an exemption to a public 
water system, it must at the same time prescribe a schedule for 
compliance (including increments of progress or measures to develop an 
alternative source of water supply) and implementation of appropriate 
control measures that the State requires the system to meet while the 
exemption is in effect. Under section 1416(b)(2)(A), the schedule 
prescribed shall require compliance as expeditiously as practicable (to 
be determined by the State), but no later than 3 years after the 
effective date for the regulations established pursuant to section 
1412(b)(10). For public water systems which do not serve more than a 
population of 3,300 and which need financial assistance for the 
necessary improvements, EPA or the State may renew an exemption for one 
or more additional two-year periods, but not to exceed a total of 6 
years, if the system establishes that it is taking all practicable 
steps to meet the requirements above. A public water system shall not 
be granted an exemption unless it can establish that either: (1) the 
system cannot meet the standard without capital improvements that 
cannot be completed prior to the date established pursuant to section 
1412(b)(10); (2) in the case of a system that needs financial 
assistance for the necessary implementation, the system has entered 
into an agreement to obtain financial assistance pursuant to section 
1452 or any other Federal or state program; or (3) the system has 
entered into an enforceable agreement to become part of a regional 
public water system.
3. Summary of Major Comments
    Several commenters agreed with the proposal not to list variances 
technologies for the Stage 2 DBPR. One commenter requested that EPA 
modify the methodology used to assess affordability. As mentioned 
earlier, EPA is currently reevaluating its national-level affordability 
criteria and has solicited recommendations from both the NDWAC and the 
SAB as part of this review. EPA intends to apply the revised criteria 
to the Stage 2 DBPR for the purpose of determining whether to enable 
States to give variances.

L. Requirements for Systems to Use Qualified Operators

    EPA believes that systems that must make treatment changes to 
comply with requirements to reduce microbiological risks and risks from 
disinfectants and disinfection byproducts should be operated by 
personnel who are qualified to recognize and respond to problems. 
Subpart H systems were required to be operated by qualified operators 
under the SWTR (Sec.  141.70). The Stage 1 DBPR added requirements for 
all disinfected systems to be operated by qualified personnel who meet 
the requirements specified by the State, which may differ based on 
system size and type. The rule also requires that States maintain a 
register of qualified operators (40 CFR 141.130(c)). While the Stage 2 
DBPR requirements do not supercede or modify the requirement that 
disinfected systems be operated by qualified operators, such personnel 
play an important role in delivering drinking water that meets Stage 2 
MCLs to the public. States should also review and modify, as required, 
their qualification standards to take into account new technologies 
(e.g., ultraviolet (UV) disinfection) and new compliance requirements 
(including simultaneous compliance and consecutive system 
requirements). EPA received only one comment on this topic; the 
commenter supported the need for a qualified operator.

M. System Reporting and Recordkeeping Requirements

1. Today's Rule
    Today's Stage 2 DBPR, consistent with the existing system reporting 
and recordkeeping regulations under 40 CFR 141.134 (Stage 1 DBPR), 
requires public water systems (including consecutive systems) to report 
monitoring data to States within ten days after the end of the 
compliance period. In addition, systems are required to submit the data 
required in Sec.  141.134. These data are required to be submitted 
quarterly for any monitoring conducted quarterly or more frequently, 
and within ten days of the end of the monitoring period for less 
frequent monitoring. As with other chemical analysis data, the system 
must keep the results for 10 years.
    In addition to the existing Stage 1 reporting requirements, today's 
rule requires systems to perform specific IDSE-related reporting to the 
primacy agency, except for systems serving fewer than 500 for which the 
State or primacy agency has waived this requirement. Required reporting 
includes submission of IDSE monitoring plans, 40/30 certification, and 
IDSE reports. This reporting must be accomplished on the schedule 
specified in the rule (see Sec.  141.600(c)) and discussed in section 
IV.E of today's preamble. System submissions must include the elements 
identified in subpart U and discussed further in section IV.F of 
today's preamble. These elements include recommended Stage 2 compliance 
monitoring sites as part of the IDSE report.
    Systems must report compliance with Stage 2 TTHM and HAA5 MCLs 
(0.080 mg/LTTHM and 0.060 mg/L HAA5, as LRAAs) according to the 
schedules specified in Sec. Sec.  141.620 and 141.629 and discussed in 
section IV.E of today's preamble. Reporting for DBP monitoring, as 
described previously, will remain generally consistent with current 
public water system reporting requirements (Sec.  141.31 and Sec.  
141.134); systems will be required to calculate and report each LRAA 
(instead of the system's RAA) and each individual monitoring result (as 
required under the Stage 1 DBPR). Systems will also be required to 
provide a report to the State about each operational evaluation within 
90 days, as discussed in section IV.H. Reports and evaluations must be 
kept for 10 years and may prove valuable in identifying trends and 
recurring issues.
2. Summary of Major Comments
    EPA requested comment on all system reporting and recordkeeping 
requirements. Commenters generally supported EPA's proposed 
requirements, but expressed concern about two specific issues. The 
first issue was the data management and tracking difficulties that 
States would face if EPA finalized a monitoring approach which had both 
plant-based and population-based requirements, as was proposed. Since 
today's rule contains only population-based monitoring requirements, 
this concern is no longer an issue. See section IV.G in today's 
preamble for further discussion.
    The second concern related to reporting associated with the IDSE. 
Commenters who supported an approach other than the IDSE for 
determining Stage 2 compliance monitoring locations did not support 
IDSE-related reporting. The IDSE remains a key component of the final 
rule; thus, EPA has retained IDSE-related reporting. However, the 
Agency has modified both the content and the timing of the reporting to 
reduce the burden. See sections IV.F and IV.E, respectively, of today's 
preamble for further discussion.

N. Approval of Additional Analytical Methods

1. Today's Rule
    EPA is taking final action to:
    (1) allow the use of 13 methods published by the Standard Methods 
Committee in Standard Methods for the Examination of Water and 
Wastewater,

[[Page 437]]

20th edition, 1998 (APHA 1998) and 12 methods in Standard Methods 
Online.
    (2) approve three methods published by American Society for Testing 
and Materials International.
    (3) approve EPA Method 327.0 Revision 1.1 (USEPA 2005h) for daily 
monitoring of chlorine dioxide and chlorite, EPA Method 552.3 (USEPA 
2003f) for haloacetic acids (five) (HAA5), EPA Methods 317.0 Revision 2 
(USEPA 2001c) and 326.0 (USEPA 2002) for bromate, chlorite, and 
bromide, EPA Method 321.8 (USEPA 2000g) for bromate only, and EPA 
Method 415.3 Revision 1.1 (USEPA 2005l) for total organic carbon (TOC) 
and specific ultraviolet absorbance (SUVA).
    (4) update the citation for EPA Method 300.1 (USEPA 2000h) for 
bromate, chlorite, and bromide.
    (5) standardize the HAA5 sample holding times and the bromate 
sample preservation procedure and holding time.
    (6) add the requirement to remove inorganic carbon prior to 
determining TOC or DOC, remove the specification of type of acid used 
for TOC/DOC sample preservation; and require that TOC samples be 
preserved at the time of collection.
    (7) clarify which methods are approved for magnesium hardness 
determinations (40 CFR 141.131 and 141.135).
2. Background and Analysis
    The Stage 1 Disinfectants and Disinfection Byproducts Rule (Stage 1 
DBPR) was promulgated on December 16, 1998 (USEPA 1998a) and it 
included approved analytical methods for DBPs, disinfectants, and DBP 
precursors. Additional analytical methods became available subsequent 
to the rule and were proposed in the Stage 2 Disinfectants and 
Disinfection Byproducts Rule (Stage 2 DBPR) (USEPA 2003a). These 
methods are applicable to monitoring that is required under the Stage 1 
DBPR. After the Stage 2 DBPR proposal, analytical methods for 
additional drinking water contaminants were proposed for approval in a 
Methods Update Rule proposal (USEPA 2004). The Stage 2 DBPR and Methods 
Update Rule proposals both included changes in the same sections of the 
CFR. EPA decided to make all the changes to Sec.  141.131 as part of 
the Stage 2 DBPR and the remainder of the methods that were proposed 
with the Stage 2 DBPR will be considered as part of the Methods Update 
Rule, which will be finalized at a later date. Two ASTM methods, D 
1253-86(96) and D 1253-03, that were proposed in the Methods Update 
Rule, are being approved for measuring chlorine residual as part of 
today's action.
    Minor corrections have been made in two of the methods that were 
proposed in the Stage 2 DBPR. In today's rule, the Agency is approving 
EPA Method 327.0 (Revision 1.1, 2005) which corrects three 
typographical errors in the proposed method.
    EPA is also approving EPA Method 415.3 (Revision 1.1, 2005), which 
does not contain the requirement that samples for the analysis of TOC 
must be received within 48 hours of sample collection.
    A summary of the methods that are included in today's rule is 
presented in Table IV.N-1.

                            Table IV.N-1. Analytical Methods Approved in Today's Rule
----------------------------------------------------------------------------------------------------------------
                                                       Standard methods    Standard methods
             Analyte                  EPA method         20th edition           online               Other
----------------------------------------------------------------------------------------------------------------
                                     Sec.   141.131--Disinfection Byproducts
----------------------------------------------------------------------------------------------------------------
HAA5............................  552.3.............  6251 B............  6251 B-94.........  ..................
Bromate.........................  317.0, Revision     ..................  ..................  ASTM D 6581-00
                                   2.0.
                                  321.8.............
                                  326.0.............
Chlorite (monthly or daily).....  317.0, Revision     ..................  ..................  ASTM D 6581-00
                                   2.0.
                                  326.0.............
Chlorite (daily)................  327.0, Revision     4500-ClO2 E.......  4500-ClO2 E-00....  ..................
                                   1.1.
---------------------------------
                                          Sec.   141.131--Disinfectants
----------------------------------------------------------------------------------------------------------------
Chlorine (free, combined, total)  ..................  4500-Cl D.........  4500-Cl D-00......  ASTM D 1253-86(96)
                                                      4500-Cl F.........  4500-Cl F-00......  ASTM D 1253-03
                                                      4500-Cl G.........  4500-Cl G-00......
Chlorine (total)................  ..................  4500-Cl E.........  4500-Cl E-00......  ..................
                                                      4500-Cl I.........  4500-Cl I-00......
Chlorine (free).................  ..................  4500-Cl H.........  4500-Cl H-00......  ..................
Chlorine Dioxide................  327.0, Revision     4500-ClO2 D.......  4500-ClO2 E-00....  ..................
                                   1.1.               4500-ClO2 E.......
---------------------------------
                                        Sec.   141.131--Other parameters
----------------------------------------------------------------------------------------------------------------
Bromide.........................  317.0, Revision     ..................  ..................  ASTM D 6581-00
                                   2.0.
                                  326.0.............
TOC/DOC.........................  415.3, Revision     5310 B............  5310 B-00.........  ..................
                                   1.1.               5310 C............  5310 C-00.........
                                                      5310 D............  5310 D-00.........
UV254...........................  415.3, Revision     5910 B............  5910 B-00.........  ..................
                                   1.1.
SUVA............................  415.3, Revision     ..................  ..................  ..................
                                   1.1.
----------------------------------------------------------------------------------------------------------------


[[Page 438]]

O. Laboratory Certification and Approval

1. PE Acceptance Criteria
    a. Today's rule. Today's rule maintains the requirements of 
laboratory certification for laboratories performing analyses to 
demonstrate compliance with MCLs and all other analyses to be conducted 
by approved parties. It revises the acceptance criteria for performance 
evaluation (PE) studies which laboratories must pass as part of the 
certification program. The new acceptance limits are effective 60 days 
after promulgation. Laboratories that were certified under the Stage 1 
DBPR PE acceptance criteria will be subject to the new criteria when it 
is time for them to analyze their annual DBP PE sample(s). Today's rule 
also requires that TTHM and HAA5 analyses that are performed for the 
IDSE or system-specific study be conducted by laboratories certified 
for those analyses.

     Table IV.O-1.--Performance Evaluation (PE) Acceptance Criteria
------------------------------------------------------------------------
                                      Acceptance
                                        limits
                DBP                  (percent of         Comments
                                     true value)
------------------------------------------------------------------------
TTHM
    Chloroform.....................       20   all 4 individual THM
                                                   acceptance limits in
                                                   order to successfully
                                                   pass a PE sample for
                                                   TTHM
    Bromodichloromethane...........       20
    Dibromochloromethane...........       20
    Bromoform......................       20
HAA5
    Monochloroacetic Acid..........       40   the acceptance limits
                                                   for 4 out of 5 of the
                                                   HAA5 compounds in
                                                   order to successfully
                                                   pass a PE sample for
                                                   HAA5
    Dichloroacetic Acid............       40
    Trichloroacetic Acid...........       40
    Monobromoacetic Acid...........       40
    Dibromoacetic Acid.............       40
Chlorite...........................       30
Bromate............................       30
------------------------------------------------------------------------

    b. Background and analysis. The Stage 1 DBPR (USEPA 1998a) 
specified that in order to be certified the laboratory must pass an 
annual performance evaluation (PE) sample approved by EPA or the State 
using each method for which the laboratory wishes to maintain 
certification. The acceptance criteria for the DBP PE samples were set 
as statistical limits based on the performance of the laboratories in 
each study. This was done because EPA did not have enough data to 
specify fixed acceptance limits.
    Subsequent to promulgation of the Stage 1 DBPR, EPA was able to 
evaluate data from PE studies conducted during the Information 
Collection Rule (USEPA 1996) and during the last five general Water 
Supply PE studies. Based on the evaluation process as described in the 
proposed Stage 2 DBPR (USEPA 2003a), EPA determined that fixed 
acceptance limits could be established for the DBPs. Today's action 
replaces the statistical PE acceptance limits with fixed limits 
effective one year after promulgation.
    c. Summary of major comments. Four commenters supported the fixed 
acceptance criteria as presented in the proposed rule. One requested 
that a minimum concentration be set for each DBP in the PE studies, so 
that laboratories would not be required to meet tighter criteria in the 
PE study than they are required to meet with the minimum reporting 
level (MRL) check standard. EPA has addressed this concern by directing 
the PE sample suppliers to use concentrations no less than 10 [mu]g/L 
for the individual THM and HAAs, 100 [mu]g/L for chlorite, and 7 [mu]g/
L for bromate in PE studies used for certifying drinking water 
laboratories.
    Two commenters requested that the effective date for the new PE 
acceptance criteria be extended from 60 days to 180 days, because they 
felt that 60 days was not enough time for laboratories to meet the new 
criteria. EPA realized from those comments that the original intent of 
the proposal was not clearly explained; the 60 days was to be the 
deadline for when the PE providers must change the acceptance criteria 
that are used when the studies are conducted. Laboratories would have 
to meet the criteria when it is time for them to analyze their annual 
PE samples in order to maintain certification. Depending upon when the 
last PE sample was analyzed, laboratories could have up to one year to 
meet the new criteria. In order to eliminate this confusion, EPA has 
modified the rule language to allow laboratories one year from today's 
date to meet the new PE criteria.
2. Minimum Reporting Limits
    a. Today's rule. EPA is establishing regulatory minimum reporting 
limits (MRLs) for compliance reporting of DBPs by Public Water Systems. 
These regulatory MRLs (Table IV.O-2) also define the minimum 
concentrations that must be reported as part of the Consumer Confidence 
Reports (40 CFR Sec.  141.151(d)). EPA is incorporating MRLs into the 
laboratory certification program for DBPs by requiring laboratories to 
include a standard near the MRL concentration as part of the 
calibration curve for each DBP and to verify the accuracy of the 
calibration curve at the MRL concentration by analyzing an MRL check 
standard with a concentration less than or equal to 110% of the MRL 
with each batch of samples. The measured DBP concentration for the MRL 
check standard must be 50% of the expected value, if any 
field sample in the batch has a concentration less than 5 times the 
regulatory MRL.

[[Page 439]]



                               Table IV.O-2.--Regulatory Minimum Reporting Levels
----------------------------------------------------------------------------------------------------------------
                                                 Minimum reporting level
                      DBP                               (mg/L) \1\                       Comments
----------------------------------------------------------------------------------------------------------------
TTHM \2\
    Chloroform.................................                   0.0010
    Bromodichloromethane.......................                   0.0010
    Dibromochloromethane.......................                   0.0010
    Bromoform..................................                   0.0010
HAA5 \2\
    Monochloroacetic Acid......................                   0.0020
    Dichloroacetic Acid........................                   0.0010
    Trichloroacetic Acid.......................                   0.0010
    Monobromoacetic Acid.......................                   0.0010
    Dibromoacetic Acid.........................                   0.0010
Chlorite.......................................                    0.020  Applicable to monitoring as prescribed
                                                                           in Sec.   141.132(b)(2)(i)(B) and
                                                                           (b)(2)(ii).
Bromate........................................         0.0050 or 0.0010  Laboratories that use EPA Methods
                                                                           317.0 Revision 2.0, 326.0 or 321.8
                                                                           must meet a 0.0010 mg/L MRL for
                                                                           bromate.
----------------------------------------------------------------------------------------------------------------
\1\ The calibration curve must encompass the regulatory minimum reporting level (MRL) concentration. Data may be
  reported for concentrations lower than the regulatory MRL as long as the precision and accuracy criteria are
  met by analyzing an MRL check standard at the lowest reporting limit chosen by the laboratory. The laboratory
  must verify the accuracy of the calibration curve at the MRL concentration by analyzing an MRL check standard
  with a concentration less than or equal to 110% of the MRL with each batch of samples. The measured
  concentration for the MRL check standard must be 50% of the expected value, if any field sample in
  the batch has a concentration less than 5 times the regulatory MRL. Method requirements to analyze higher
  concentration check standards and meet tighter acceptance criteria for them must be met in addition to the MRL
  check standard requirement.
\2\ When adding the individual trihalomethane or haloacetic acid concentrations to calculate the TTHM or HAA5
  concentrations, respectively, a zero is used for any analytical result that is less than the MRL concentration
  for that DBP, unless otherwise specified by the State.

    b. Background and analysis. EPA proposed to establish regulatory 
MRLs for DBPs in order to define expectations for reporting compliance 
monitoring data to the Primacy Agencies and in the Consumer Confidence 
Reports. The proposed MRLs were generally based on those used during 
the Information Collection Rule (USEPA 1996), because an analysis of 
the quality control data set from the Information Collection Rule (Fair 
et al. 2002) indicated that laboratories are able to provide 
quantitative data down to those concentrations.
    EPA also proposed that laboratories be required to demonstrate 
ability to quantitate at the MRL concentrations by analyzing an MRL 
check standard and meeting accuracy criteria on each day that 
compliance samples are analyzed. Three public commenters noted that 
meeting the accuracy requirement for the MRL check standard did not 
contribute to the quality of the data in cases in which the 
concentration of a DBP in the samples was much higher than the MRL. For 
example, if chloroform concentrations are always greater than 0.040 mg/
L in a water system's samples, then verifying accurate quantitation at 
0.0010 mg/L is unnecessary and may require the laboratory to dilute 
samples or maintain two calibration curves in order to comply with the 
requirement. EPA has taken this into consideration in today's rule and 
has adjusted the requirement accordingly. EPA is maintaining the 
requirement for all laboratories to analyze the MRL check standard, but 
the laboratory is only required to meet the accuracy criteria (50%) if a field sample has a concentration less than five times 
the regulatory MRL concentration.
    EPA proposed a regulatory MRL of 0.200 mg/L for chlorite, because 
data from the Information Collection Rule indicated that most samples 
would contain concentrations greater than 0.200 mg/L (USEPA 2003c). EPA 
also took comment on a lower MRL of 0.020 mg/L. Commenters were evenly 
divided concerning which regulatory MRL concentration should be adopted 
in the final rule. EPA has decided to set the chlorite regulatory MRL 
at 0.020 mg/L in today's rule. This decision was based on two factors. 
First, the approved analytical methods for determining compliance with 
the chlorite MCL can easily support an MRL of 0.020 mg/L. More 
importantly, since the proposal, EPA has learned that water systems 
that have low chlorite concentrations in their water have been 
obtaining data on these low concentrations from their laboratories and 
have been using these data in their Consumer Confidence Reports. 
Setting the MRL at 0.020 mg/L is reflective of current practices in 
laboratories and current data expectations by water systems.
    c. Summary of major comments. There were no major comments.

P. Other Regulatory Changes

    As part of today's action, EPA has included several 
``housekeeping'' actions to remove sections of Part 141 that are no 
longer effective. These sections have been superceded by new 
requirements elsewhere in Part 141.
    Sections 141.12 (Maximum contaminant levels for total 
trihalomethanes) and 141.30 (Total trihalomethanes sampling, analytical 
and other requirements) were promulgated as part of the 1979 TTHM Rule. 
These sections have been superceded in their entirety by Sec.  141.64 
(Maximum contaminant levels for disinfection byproducts) and subpart L 
(Disinfectant Residuals, Disinfection Byproducts, and Disinfection 
Byproduct Precursors), respectively, as of December 31, 2003. Also, 
Sec.  141.32 (Public notification) has been superceded by subpart Q 
(Public Notification of Drinking Water Violations), which is now fully 
in effect.
    Section 553 of the Administrative Procedure Act, 5 U.S.C. 
553(b)(B), provides that, when an agency for good cause finds that 
notice and public procedure are impracticable, unnecessary, or contrary 
to the public interest, the agency may issue a rule without providing 
prior notice and an opportunity for public comment. In addition to 
updating methods, this rule also makes minor corrections to the 
National Primary Drinking Water Regulations, specifically the Public 
Notification tables (Subpart Q, Appendices A and B). Two final drinking 
water rules (66 FR 6976 and 65 FR 76708) inadvertently added new 
endnotes to two existing tables using the same endnote numbers. This 
rule corrects this technical drafting error by

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renumbering the endnote citations in these two tables. Thus, additional 
notice and public comment is not necessary. EPA finds that this 
constitutes ``good cause'' under 5 U.S.C. 553(b)(B). For the same 
reasons, EPA is making this rule change effective upon publication. 5 
U.S.C. 553(d)(3).

V. State Implementation

A. Today's Rule

    This section describes the regulations and other procedures and 
policies States must adopt to implement today's rule. States must 
continue to meet all other conditions of primacy in 40 CFR Part 142. To 
implement the Stage 2 DBPR, States must adopt revisions to the 
following:

    --Sec.  141.2--Definitions
    --Sec.  141.33--Record maintenance;
    --Sec.  141.64--Maximum contaminant levels for disinfection 
byproducts;
    --subpart L--Disinfectant Residuals, Disinfection Byproducts, and 
Disinfection Byproduct Precursors;
    --subpart O, Consumer Confidence Reports;
    --subpart Q, Public Notification of Drinking Water Violations;
    --new subpart U, Initial Distribution System Evaluation; and
    --new subpart V, Stage 2 Disinfection Byproducts Requirements.
1. State Primacy Requirements for Implementation Flexibility
    In addition to adopting basic primacy requirements specified in 40 
CFR part 142, States are required to address applicable special primacy 
conditions. Special primacy conditions pertain to specific regulations 
where implementation of the rule involves activities beyond general 
primacy provisions. The purpose of these special primacy requirements 
in today's rule is to ensure State flexibility in implementing a 
regulation that (1) applies to specific system configurations within 
the particular State and (2) can be integrated with a State's existing 
Public Water Supply Supervision Program. States must include these 
rule-distinct provisions in an application for approval or revision of 
their program. These primacy requirements for implementation 
flexibility are discussed in this section.
    To ensure that a State program includes all the elements necessary 
for an effective and enforceable program under today's rule, a State 
primacy application must include a description of how the State will 
implement a procedure for modifying consecutive system and wholesale 
system monitoring requirements on a case-by-case basis, if a State will 
use the authority to modify monitoring requirements under this special 
primacy condition.
2. State Recordkeeping Requirements
    Today's rule requires States to keep additional records of the 
following, including all supporting information and an explanation of 
the technical basis for each decision:

    --very small system waivers.
    --IDSE monitoring plans.
    --IDSE reports and 40/30 certifications, plus any modifications 
required by the State.
    --operational evaluations conducted by the system.
3. State Reporting Requirements
    Today's rule has no new State reporting requirements.
4. Interim Primacy
    States that have primacy for every existing NPDWR already in effect 
may obtain interim primacy for this rule, beginning on the date that 
the State submits the application for this rule to USEPA, or the 
effective date of its revised regulations, whichever is later. A State 
that wishes to obtain interim primacy for future NPDWRs must obtain 
primacy for today's rule. As described in Section IV.F, EPA expects to 
work with States to oversee the individual distribution system 
evaluation process that begins shortly after rule promulgation.
5. IDSE Implementation
    As discussed in section IV.E, many systems will be performing 
certain IDSE activities prior to their State receiving primacy. During 
that period, EPA will act as the primacy agency, but will consult and 
coordinate with individual States to the extent practicable and to the 
extent that States are willing and able to do so. In addition, prior to 
primacy, States may be asked to assist EPA in identifying and 
confirming systems that are required to comply with certain IDSE 
activities. Once the State has received primacy, it will become 
responsible for IDSE implementation activities.

B. Background and Analysis

    SDWA establishes requirements that a State or eligible Indian Tribe 
must meet to assume and maintain primary enforcement responsibility 
(primacy) for its PWSs. These requirements include the following 
activities: (1) Adopting drinking water regulations that are no less 
stringent than Federal drinking water regulations; (2) adopting and 
implementing adequate procedures for enforcement; (3) keeping records 
and making reports available on activities that EPA requires by 
regulation; (4) issuing variances and exemptions (if allowed by the 
State), under conditions no less stringent than allowed under SDWA; and 
(5) adopting and being capable of implementing an adequate plan for the 
provisions of safe drinking water under emergency situations.
    40 CFR part 142 sets out the specific program implementation 
requirements for States to obtain primacy for the public water supply 
supervision program as authorized under SDWA section 1413. In addition 
to adopting basic primacy requirements specified in 40 CFR Part 142, 
States may be required to adopt special primacy provisions pertaining 
to specific regulations where implementation of the rule involves 
activities beyond general primacy provisions. States must include these 
regulation specific provisions in an application for approval of their 
program revision.
    The current regulations in 40 CFR 142.14 require States with 
primacy to keep various records, including the following: analytical 
results to determine compliance with MCLs, MRDLs, and treatment 
technique requirements; PWS inventories; State approvals; enforcement 
actions; and the issuance of variances and exemptions. Today's final 
rule requires States to keep additional records, including all 
supporting information and an explanation of the technical basis for 
decisions made by the State regarding today's rule requirements. The 
State may use these records to identify trends and determine whether to 
limit the scope of operational evaluations. EPA currently requires in 
40 CFR 142.15 that States report to EPA information such as violations, 
variance and exemption status, and enforcement actions; today's rule 
does not add additional reporting requirements or modify existing 
requirements.
    On April 28, 1998, EPA amended its State primacy regulations at 40 
CFR 142.12 to incorporate the new process identified in the 1996 SDWA 
Amendments for granting primary enforcement authority to States while 
their applications to modify their primacy programs are under review 
(63 FR 23362, April 28, 1998) (USEPA 1998f). The new process grants 
interim primary enforcement authority for a new or revised regulation 
during the period in which EPA is making a determination with regard to 
primacy for that new or revised regulation. This interim enforcement 
authority begins on the date of the primacy application submission or 
the effective date of the

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new or revised State regulation, whichever is later, and ends when EPA 
makes a final determination. However, this interim primacy authority is 
only available to a State that has primacy (including interim primacy) 
for every existing NPDWR in effect when the new regulation is 
promulgated. States that have primacy for every existing NPDWR already 
in effect may obtain interim primacy for this rule and a State that 
wishes to obtain interim primacy for future NPDWRs must obtain primacy 
for this rule.
    EPA is aware that due to the complicated wholesale system-
consecutive system relationships that exist nationally, there will be 
cases where the standard monitoring framework will be difficult to 
implement. Therefore, States may develop, as a special primacy 
condition, a program under which the State can modify monitoring 
requirements for consecutive systems. These modifications must not 
undermine public health protection and all systems, including 
consecutive systems, must comply with the TTHM and HAA5 MCLs based on 
the LRAA at each compliance monitoring location. Each consecutive 
system must have at least one compliance monitoring location. However, 
such a program allows the State to establish monitoring requirements 
that account for complicated distribution system relationships, such as 
where neighboring systems buy from and sell to each other regularly 
throughout the year, water passes through multiple consecutive systems 
before it reaches a user, or a large group of interconnected systems 
have a complicated combined distribution system. EPA has developed a 
guidance manual to address these and other consecutive system issues.

C. Summary of Major Comments

    Public comment generally supported the special primacy requirements 
in the August 11, 2003 proposal, and many commenters expressed 
appreciation for the flexibility the special primacy requirements 
provided to States.
    Many commenters expressed concern about EPA as the implementer 
instead of the State, given the existing relationship between the State 
and system. EPA agrees that States perform an essential role in rule 
implementation and intends to work with States to the greatest extent 
possible, consistent with the rule schedule promulgated today. EPA 
believes that pre-promulgation coordination with States, changes in the 
final rule strongly supported by States (e.g., population-based 
monitoring instead of plant-based monitoring), and the staggered rule 
schedule will facilitate State involvement in pre-primacy 
implementation.
    Many commenters also requested that the State have more flexibility 
to grant sampling waivers and exemptions. EPA believes that it has 
struck a reasonable balance among competing objectives in granting 
State flexibility. State flexibility comes at a resource cost and 
excessive system-by-system flexibility could overwhelm State resources. 
Also, EPA believes that much of the monitoring and water quality 
information a State would need to properly consider whether a waiver is 
appropriate is generally not available and, if available, difficult to 
evaluate.

VI. Economic Analysis

    This section summarizes the Economic Analysis for the Final Stage 2 
Disinfectants and Disinfection Byproducts Rule (Economic Analysis (EA)) 
(USEPA 2005a). The EA is an evaluation of the benefits and costs of 
today's final rule and other regulatory alternatives the Agency 
considered. Specifically, this evaluation addresses both quantified and 
non-quantified benefits to PWS consumers, including the general 
population and sensitive subpopulations. Costs are presented for PWSs, 
States, and consumer households. Also included is a discussion of 
potential risks from other contaminants, uncertainties in benefit and 
cost estimates, and a summary of major comments on the EA for the 
proposed Stage 2 DBPR.
    EPA relied on data from several epidemiologic and toxicologic 
studies, the Information Collection Rule (ICR), and other sources, 
along with analytical models and input from technical experts, to 
understand DBP risk, occurrence, and PWS treatment changes that will 
result from today's rule. Benefits and costs are presented as 
annualized values using social discount rates of three and seven 
percent. The time frame used for benefit and cost comparisons is 25 
years--approximately five years account for rule implementation and 20 
years for the average useful life of treatment technologies.
    EPA has prepared this EA to comply with the requirements of SDWA, 
including the Health Risk Reduction and Cost Analysis required by SDWA 
section 1412(b)(3)(C), and Executive Order 12866, Regulatory Planning 
and Review. The full EA is available in the docket for today's rule, 
which is available online as described in the ADDRESSES section. The 
full document provides detailed explanations of the analyses summarized 
in this section and additional analytical results.

A. Regulatory Alternatives Considered

    The Stage 2 DBPR is the second in a set of rules that address 
public health risks from DBPs. EPA promulgated the Stage 1 DBPR to 
decrease average exposure to DBPs and mitigate associated health 
risks--compliance with TTHM and HAA5 MCLs is based on averaging 
concentrations across the distribution system. In developing the Stage 
2 DBPR, EPA sought to identify and further reduce remaining risks from 
exposure to chlorinated DBPs.
    The regulatory options EPA considered for the Stage 2 DBPR are the 
direct result of a consensus rulemaking process (Federal Advisory 
Committee Act (FACA) process) that involved various drinking water 
stakeholders (see Section III for a description of the FACA process). 
The Advisory Committee considered the following key questions during 
the negotiation process for the Stage 2 DBPR:
     What are the remaining health risks after implementation 
of the Stage 1 DBPR?
     What are approaches to addressing these risks?
     What are the risk tradeoffs that need to be considered in 
evaluating these approaches?
     How do the estimated costs of an approach compare to 
reductions in peak DBP occurrences and overall DBP exposure for that 
approach?
    The Advisory Committee considered DBP occurrence estimates to be 
important in understanding the nature of public health risks. Although 
the ICR data were collected prior to promulgation of the Stage 1 DBPR, 
they were collected under a similar sampling strategy. The data support 
the concept that a system could be in compliance with the RAA Stage 1 
DBPR MCLs of 0.080 mg/L and 0.060 mg/L for TTHM and HAA5, respectively, 
and yet have points in the distribution system with either periodically 
or consistently higher DBP levels.
    Based on these findings, the Advisory Committee discussed an array 
of alternatives to address disproportionate risk within distribution 
systems. Alternative options included lowering DBP MCLs, revising the 
method for MCL compliance determination e.g., requiring individual 
sampling locations to meet the MCL as an LRAA or requiring that no 
samples exceed the MCL), and combinations of both. The Advisory 
Committee also considered the associated technology changes and costs 
for these alternatives. After narrowing down options, the Advisory 
Committee

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primarily focused on four types of alternative MCL scenarios. These are 
the alternatives EPA evaluated in the EA, as follows:

Preferred Alternative
    --MCLs of 0.080 mg/L for TTHM and 0.060 mg/L for HAA5 as LRAAs
    --Bromate MCL remaining at 0.010 mg/L
Alternative 1
    --MCLs of 0.080 mg/L for TTHM and 0.060 mg/L for HAA5 as LRAAs
    --Bromate MCL of 0.005 mg/L
Alternative 2
    --MCLs of 0.080 mg/L for TTHM and 0.060 mg/L for HAA5 as absolute 
maximums for individual measurements
    --Bromate MCL remaining at 0.010 mg/L
Alternative 3
    --MCLs of 0.040 mg/L for TTHM and 0.030 mg/L for HAA5 as RAAs
    --Bromate MCL remaining at 0.010 mg/L.

    Figure VI.A-1 shows how compliance would be determined under each 
of the TTHM/HAA5 alternatives described and the Stage 1 DBPR for a 
hypothetical large surface water system. This hypothetical system has 
one treatment plant and measures TTHM in the distribution system in 
four locations per quarter (the calculation methodology shown would be 
the same for HAA5). Ultimately, the Advisory Committee recommended the 
Preferred Alternative in combination with an IDSE requirement 
(discussed in Section IV.F).

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B. Analyses That Support Today's Final Rule

    EPA's goals in designing the Stage 2 DBPR were to protect public 
health by reducing peak DBP levels in the distribution system while 
maintaining microbial protection. As described earlier, the Stage 1 
DBPR reduces overall average DBP levels, but specific locations within 
distribution systems can still experience relatively high DBP 
concentrations. EPA believes that high DBP concentrations should be 
reduced due to the potential association of DBPs with cancer, as well 
as reproductive and developmental health effects.
    EPA analyzed the benefits and costs of the four regulatory 
alternatives presented in the previous section. Consistent with the 
recommendations of the Advisory Committee, EPA is establishing the 
preferred alternative to achieve the Agency's goals for the Stage 2 
DBPR. The following discussion summarizes EPA's analyses that support 
today's final rule. This discussion explains how EPA predicted water 
quality and treatment changes, estimated benefits and costs, and 
assessed the regulatory alternatives.
1. Predicting Water Quality and Treatment Changes
    Water quality and treatment data from the ICR were used in 
predicting treatment plant technology changes (i.e. compliance 
forecasts) and reductions in DBP exposure resulting from the Stage 2 
DBPR. Because ICR data were gathered prior to Stage 1 DBPR compliance 
deadlines, EPA first accounted for treatment changes resulting from the 
Stage 1 DBPR. Benefit and cost estimates for the Stage 2 DBPR reflect 
changes following compliance with the Stage 1 DBPR.
    The primary model used to predict changes in treatment and 
reductions in DBP levels was the Surface Water Analytical Tool (SWAT), 
which EPA developed using results from the ICR. SWAT results were 
applied directly for large and medium surface water systems and were 
adjusted for small surface water systems to account for differences in 
source water DBP precursor levels and operational constraints in small 
systems. EPA used ICR data and a Delphi poll process (a group of 
drinking water experts who provided best professional judgment in a 
structured format) to project technologies selected by ground water 
systems.
    To address uncertainty in SWAT predictions, EPA also predicted 
treatment changes using a second methodology, called the ``ICR Matrix 
Method.'' Rather than a SWAT-predicted pre-Stage 1 baseline, the ICR 
Matrix Method uses unadjusted ICR TTHM and HAA5 pre-Stage 1 data to 
estimate the percent of plants changing technology to comply with the 
Stage 2 DBPR. EPA gives equal weight to SWAT and ICR Matrix Method 
predictions in estimating Stage 2 compliance forecasts and resultant 
reductions in DBP exposure. The ICR Matrix Method is also used to 
estimate reductions in the occurrence of peak TTHM and HAA5 
concentrations because SWAT-predicted TTHM and HAA5 concentrations are 
valid only when considering national averages, not at the plant level.
    When evaluating compliance with a DBP MCL, EPA assumed that systems 
would maintain DBP levels at least 20 percent below the MCL. This 
safety margin represents the level at which systems typically take 
action to ensure they meet a drinking water standard and reflects 
industry practice. In addition, the safety margin accounts for year-to-
year fluctuations in DBP levels. To address the impact of the IDSE, EPA 
also analyzed compliance using a safety margin of 25 percent based on 
an analysis of spatial variability in TTHM and HAA5 occurrence. EPA 
assigned equal probability to the 20 and 25 percent safety margin for 
large and medium surface water systems for the final analysis because 
both alternatives are considered equally plausible. EPA assumes the 20 
percent operational safety margin accounts for variability in small 
surface water systems and all groundwater systems.
2. Estimating Benefits
    Quantified benefits estimates for the Stage 2 DBPR are based on 
potential reductions in fatal and non-fatal bladder cancer cases. In 
the EA, EPA included a sensitivity analysis for benefits from avoiding 
colon and rectal cancers. EPA believes additional benefits from this 
rule could come from reducing potential reproductive and developmental 
risks. EPA has not included these potential risks in the primary 
benefit analysis because of the associated uncertainty.
    The major steps in deriving and characterizing potential cancer 
cases avoided include the following: (1) estimate the current and 
future annual cases of illness from all causes; (2) estimate how many 
cases can be attributed to DBP occurrence and exposure; and (3) 
estimate the reduction in future cases corresponding to anticipated 
reductions in DBP occurrence and exposure due to the Stage 2 DBPR.
    EPA used results from the National Cancer Institute's Surveillance, 
Epidemiology, and End Results program in conjunction with data from the 
2000 U.S. Census to estimate the number of new bladder cancer cases per 
year (USEPA 2005a). Three approaches were then used to gauge the 
percentage of cases attributable to DBP exposure (i.e., population 
attributable risk (PAR)). Taken together, the three approaches provide 
a reasonable estimate of the range of potential risks. EPA notes that 
the existing epidemiological evidence has not conclusively established 
causality between DBP exposure and any health risk endpoints, so the 
lower bound of potential risks may be as low as zero.
    The first approach used the range of PAR values derived from 
consideration of five individual epidemiology studies. This range was 
used at the basis for the Stage 1 and the proposed Stage 2 economic 
analyses (i.e., 2 percent to 17 percent) (USEPA 2003a).
    The second approach used results from the Villanueva et al. (2003) 
meta-analysis. This study develops a combined Odds Ratio (OR) of 1.2 
that reflects the ever-exposed category for both sexes from all studies 
considered in the meta-analysis and yields a PAR value of approximately 
16 percent.
    The third approach used the Villanueva et al. (2004) pooled data 
analysis to develop a dose-response relationship for OR as a function 
of average TTHM exposure. Using the results from this approach, EPA 
estimates a PAR value of approximately 17 percent.
    EPA used the PAR values from all three approaches to estimate the 
number of bladder cancer cases ultimately avoided annually as a result 
of the Stage 2 DBPR. To quantify the reduction in cases, EPA assumed a 
linear relationship between average DBP concentration and relative risk 
of bladder cancer. Because of this, EPA considers these estimates to be 
an upper bound on the annual reduction in bladder cancer cases due to 
the rule.
    A lag period (i.e., cessation lag) exists between when reduction in 
exposure to a carcinogen occurs and when the full risk reduction 
benefit of that exposure reduction is realized by exposed individuals. 
No data are available that address the rate of achieving bladder cancer 
benefits resulting from DBP reductions. Consequently, EPA used data 
from epidemiological studies that address exposure reduction to 
cigarette smoke and arsenic to generate three possible cessation lag 
functions for bladder cancer and DBPs. The cessation lag functions are 
used in conjunction

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with the rule implementation schedule to project the number of bladder 
cancer cases avoided each year as a result of the Stage 2 DBPR.
    Although EPA used three approaches for estimating PAR, for 
simplicity's sake, EPA used the Villanueva et al. (2003) study to 
calculate the annual benefits of the Stage 2 DBPR. The benefits 
estimates derived from Villanueva et al. (2003) capture a substantial 
portion of the overall range of results, reflecting the uncertainty in 
both the underlying OR and PAR values, as well as the uncertainty in 
DBP reductions for Stage 2.
    To assign a monetary value to avoided bladder cancer cases, EPA 
used the value of a statistical life (VSL) for fatal cases and used two 
alternate estimates of willingness-to-pay to avoid non-fatal cases (one 
based on curable lymphoma and the other based on chronic bronchitis). 
EPA believes additional benefits from this rule could come from a 
reduction in potential reproductive and developmental risks. See 
Chapter 6 of the EA for more information on estimating benefits (USEPA 
2005a).
3. Estimating Costs
    Analyzing costs for systems to comply with the Stage 2 DBPR 
included identifying and costing treatment process improvements that 
systems will make, as well as estimating the costs to implement the 
rule, conduct IDSEs, prepare monitoring plans, perform additional 
routine monitoring, and evaluate significant DBP excursion events. The 
cost analysis for States/Primacy Agencies included estimates of the 
labor burdens for training employees on the requirements of the Stage 2 
DBPR, responding to PWS reports, and record keeping.
    All treatment costs are based on mean unit cost estimates for 
advanced technologies and chloramines. Derivation of unit costs are 
described in detail in Technologies and Costs for the Final Long Term 2 
Enhanced Surface Water Treatment Rule and Final Stage 2 Disinfectants 
and Disinfection Byproducts Rule (USEPA 2005g). Unit costs (capital and 
O&M) for each of nine system size categories are calculated using mean 
design and average daily flows values. The unit costs are then combined 
with the predicted number of plants selecting each technology to 
produce national treatment cost estimates.
    Non-treatment costs for implementation, the IDSE, monitoring plans, 
additional routine monitoring, and operational evaluations are based on 
estimates of labor hours for performing these activities and on 
laboratory costs.
    While systems vary with respect to many of the input parameters to 
the Stage 2 DBPR cost analysis (e.g., plants per system, population 
served, flow per population, labor rates), EPA believes that mean 
values for the various input parameters are appropriate to generate the 
best estimate of national costs for the rule. Uncertainty in the 
national average unit capital and O&M costs for the various 
technologies has been incorporated into the cost analysis (using Monte 
Carlo simulation procedures). Costs of the Stage 2 DBPR are estimated 
at both mean and 90 percent confidence bound values.
    EPA assumes that systems will, to the extent possible, pass cost 
increases on to their customers through increases in water rates. 
Consequently, EPA has also estimated annual household cost increases 
for the Stage 2 DBPR. This analysis includes costs for all households 
served by systems subject to the rule, costs just for those households 
served by systems actually changing treatment technologies to comply 
with the rule, costs for households served by small systems, and costs 
for systems served by surface water and ground water sources.
4. Comparing Regulatory Alternatives
    Through the analyses summarized in this section, EPA assessed the 
benefits and costs of the four regulatory alternatives described 
previously. Succeeding sections of this preamble present the results of 
these analyses. As recommended by the Advisory Committee, EPA is 
establishing the preferred regulatory alternative for today's Stage 2 
DBPR. This regulation will reduce peak DBP concentrations in 
distribution systems through requiring compliance determinations with 
existing TTHM and HAA5 MCLs using the LRAA. Further, the IDSE will 
ensure that systems identify compliance monitoring sites that reflect 
high DBP levels. EPA believes that these provision are appropriate 
given the association of DBPs with cancer, as well as potential 
reproductive and developmental health effects.
    Alternative 1 would have established the same DBP regulations as 
the preferred alternative, and would have lowered the bromate MCL from 
0.010 to 0.005 mg/L. The Advisory Committee did not recommend and EPA 
did not establish this alternative because it could have an adverse 
effect on microbial protection. The lower bromate MCL could cause many 
systems to reduce or eliminate the use of ozone, which is an effective 
disinfectant for a broad spectrum of microbial pathogens, including 
microorganisms like Cryptosporidium that are resistant to chlorine.
    Alternative 2 would have prohibited any single sample from 
exceeding the TTHM or HAA5 MCL. This is significantly more stringent 
than the preferred alternative and would likely require a large 
fraction of surface water systems to switch from their current 
treatment practices to more expensive advanced technologies. Consistent 
with the Advisory Committee, EPA does not believe such a drastic shift 
is warranted at this time.
    Similarly, Alternative 3, which would decrease TTHM and HAA5 MCLs 
to 0.040 mg/L and 0.030 mg/L, respectively, and would require a 
significant portion of surface water systems to implement expensive 
advanced technologies in place of their existing treatment. Further, 
compliance with TTHM and HAA5 MCLs under this alternative would be 
based on the RAA, which does not specifically address DBP peaks in the 
distribution system as the LRAA, in conjunction with the IDSE, are 
designed to do. Based on these considerations, EPA and the Advisory 
Committee did not favor this alternative.

C. Benefits of the Stage 2 DBPR

    The benefits analysis for the Stage 2 DBPR includes a description 
of non-quantified benefits, calculations of quantified benefits, and a 
discussion of when benefits will occur after today's final rule is 
implemented. An overview of the methods used to determine benefits is 
provided in Section VI.B. More detail can be found in the final EA. A 
summary of benefits for the Stage 2 DBPR is given in this section.
1. Nonquantified Benefits
    Non-quantified benefits of the Stage 2 DBPR include potential 
benefits from reduced reproductive and developmental risks, reduced 
risks of cancers other than bladder cancer, and improved water quality. 
EPA believes that additional benefits from this rule could come from a 
reduction in potential reproductive and developmental risks. However, 
EPA does not believe the available evidence provides an adequate basis 
for quantifying these potential risks in the primary analysis.
    Both toxicology and epidemiology studies indicate that other 
cancers may be associated with DBP exposure but currently there is not 
enough data to include them in the primary analysis. However, EPA 
believes that the association between exposure to DBPs and colon and 
rectal cancer is possibly

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significant, so an analysis of benefits is presented as a sensitivity 
analysis.
    To the extent that the Stage 2 DBPR changes perceptions of the 
health risks associated with drinking water and improves taste and 
odor, it may reduce actions such as buying bottled water or installing 
filtration devices. Any resulting cost savings would be a regulatory 
benefit. Also, as PWSs move away from conventional treatment to more 
advanced technologies, other non-health benefits are anticipated 
besides better tasting and smelling water. For example, GAC lowers 
nutrient availability for bacterial growth, produces a biologically 
more stable finished water, and facilitates management of water quality 
in the distribution system. Since GAC also removes synthetic organic 
chemicals (SOCs), it provides additional protection from exposure to 
chemicals associated with accidental spills or environmental runoff.
2. Quantified Benefits
    EPA has quantified the benefits associated with the expected 
reductions in the incidence of bladder cancer. As discussed in Section 
VI.B, EPA used the PAR values from all three approaches to estimate the 
number of bladder cancer cases ultimately avoided annually as a result 
of the Stage 2 DBPR, shown in Figure VI.C-1.
    Table VI.C-1 summarizes the estimated number of bladder cancer 
cases avoided as a result of the Stage 2 DBPR, accounting for cessation 
lag and the rule implementation schedule, and the monetized value of 
those cases. The benefits in Table VI.C-1 were developed using the PAR 
value from Villanueva et al. (2003), as described in Section VI.B. 
Table VI.C-1 summarizes the benefits for the Preferred Regulatory 
Alternative for the Stage 2 DBPR. Benefits estimates for the other 
regulatory alternatives were derived using the same methods as for the 
Preferred Regulatory Alternative and are presented in the EA.
    The confidence bounds of the results in Table VI.C-1 reflect 
uncertainty in PAR, uncertainty in the compliance forecast and 
resulting reduction in DBP concentrations, and cessation lag. 
Confidence bounds of the monetized benefits also reflect uncertainty in 
valuation parameters. An estimated 26 percent of bladder cancer cases 
avoided are fatal, and 74 percent are non-fatal (USEPA 1999b). The 
monetized benefits therefore reflect the estimate of avoiding both 
fatal and non-fatal cancers in those proportions.

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             Table VI.C-1.--Summary of Quantified Benefits for the Stage 2 DBPR (Millions of $2003)
----------------------------------------------------------------------------------------------------------------
   Annual average cases avoided    Discount rate, WTP   Annualized benefits of cases avoided
----------------------------------    for non-fatal   ---------------------------------------    Cessation lag
   Mean         5th        95th           cases            Mean         5th          95th            model
----------------------------------------------------------------------------------------------------------------
279         103         541        3%, Lymphoma......       $1,531         $233       $3,536  Smoking/Lung
                                   7% Lymphoma.......        1,246          190        2,878   Cancer
                                   3% Bronchitis.....          763          165        1,692
                                   7% Bronchitis.....          621          135        1,376
188         61          399        3%, Lymphoma......        1,032          157        2,384  Smoking/Bladder
                                   7% Lymphoma.......          845          129        1,950   Cancer
                                   3% Bronchitis.....          514          111        1,141
                                   7% Bronchitis.....          420           91          932
333         138         610        3%, Lymphoma......        1,852          282        4,276  Arsenic/Bladder
                                   7% Lymphoma.......        1,545          235        3,566   Cancer
                                   3% Bronchitis.....          922          200        2,045
                                   7% Bronchitis.....          769          167        1,704
----------------------------------------------------------------------------------------------------------------
Notes: Values are discounted and annualized in 2003$. The 90 percent confidence interval for cases incorporates
  uncertainty in PAR, reduction in average TTHM and HAA5 concentrations, and cessation lag. The 90 percent
  confidence bounds for monetized benefits reflect uncertainty in monetization inputs relative to mean cases.
  Based on TTHM as an indicator, benefits were calculated using the Villanueva et al. (2003) PAR. EPA recognizes
  that benefits may be as low as zero since causality has not yet been established between exposure to
  chlorinated water and bladder cancer. Assumes 26 percent of cases are fatal, 74 percent are non-fatal (USEPA
  1999b).
 
 Source: Exhibit 6.1, USEPA 2005a.

3. Timing of Benefits Accrual
    EPA recognizes that it is unlikely that all cancer reduction 
benefits would be realized immediately upon exposure reduction. Rather, 
it is expected that there will likely be some transition period as 
individual risks reflective of higher past exposures at the time of 
rule implementation become, over time, more reflective of the new lower 
exposures. EPA developed cessation lag models for DBPs from literature 
to describe the delayed benefits, in keeping with the recommendations 
of the SAB (USEPA 2001d). Figure VI.C-2 illustrates the effects of the 
cessation lag models. The results from the cessation lag models show 
that the majority of the potential cases avoided occur within the first 
fifteen years after initial reduced exposure to DBPs. For example, 
fifteen years after the exposure reduction has occurred, the annual 
cases avoided will be 489 for the smoking/lung cancer cessation lag 
model, 329 for the smoking/bladder cancer cessation lag model, and 534 
cases for the arsenic/bladder cancer cessation lag model. These 
represent approximately 84%, 57%, and 92%, respectively, of the 
estimated 581 annual cases ultimately avoidable by the Stage 2 DBPR.
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    In addition to the delay in reaching a steady-state level of risk 
reduction as a result of cessation lag, there is a delay in attaining 
maximum exposure reduction across the entire affected population that 
results from the Stage 2 DBPR implementation schedule. For example, 
large surface water PWSs have six years from rule promulgation to meet 
the new Stage 2 MCLs, with up to a two-year extension possible for 
capital improvements. In general, EPA assumes that a fairly constant 
increment of systems will complete installation of new treatment 
technologies each year, with the last systems installing treatment by 
2016. The delay in exposure reduction resulting from the rule 
implementation schedule is incorporated into the benefits model by 
adjusting the cases avoided for the given year and is illustrated in 
Table VI.C-2.

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   Table VI.C-2.--Bladder Cancer Cases Avoided (TTHM as Indicator) Each Year using Three Cessation Lag Models
----------------------------------------------------------------------------------------------------------------
                                                 Smoking/lung cancer     Smoking/bladder       Arsenic/bladder
                                                 cessation lag model  cancer cessation lag  cancer cessation lag
                     Year                      ----------------------         model                 model
                                                                     -------------------------------------------
                                                  Total     Percent     Total     Percent     Total     Percent
----------------------------------------------------------------------------------------------------------------
1.............................................          0          0          0          0          0          0
2.............................................          0          0          0          0          0          0
3.............................................          0          0          0          0          0          0
4.............................................          0          0          0          0          0          0
5.............................................          0          0          0          0          0          0
6.............................................         24          4         23          4         45          8
7.............................................         62         11         54          9        110         19
8.............................................        111         19         90         16        187         32
9.............................................        170         29        132         23        275         48
10............................................        220         38        161         28        334         58
11............................................        265         46        184         32        379         65
12............................................        305         53        204         35        412         71
13............................................        341         59        221         38        438         76
14............................................        371         64        237         41        458         79
15............................................        396         68        251         43        475         82
16............................................        416         72        265         46        488         84
17............................................        433         75        278         48        499         86
18............................................        448         77        289         50        509         88
19............................................        460         79        301         52        516         89
20............................................        471         81        311         54        523         90
21............................................        481         83        321         55        528         91
22............................................        489         84        330         57        533         92
23............................................        496         86        339         59        537         93
24............................................        503         87        347         60        541         93
25............................................        509         88        355         61        544        94
----------------------------------------------------------------------------------------------------------------
Notes: Percent of annual cases ultimately avoidable achieved during each of the first 25 years. The benefits
  model estimates 581 (90% CB = 229-1,079) annual cases ultimately avoidable using the Villanueva et al. (2003)
  PAR inputs and including uncertainty in these and DBP reductions. EPA recognizes that benefits may be as low
  as zero since causality has not yet been established between exposure to chlorinated water and bladder cancer.
 
Source: Summarized from detailed results presented in Exhibits E.38a, E.38e and E.38i, USEPA 2005a.

D. Costs of the Stage 2 DBPR

    National costs include those of treatment changes to comply with 
the rule as well as non-treatment costs such as for Initial 
Distribution System Evaluations (IDSEs), additional routine monitoring, 
and operational evaluations. The methodology used to estimate costs is 
described in Section VI.B. More detail is provided in the EA (USEPA 
2005a). The remainder of this section presents summarized results of 
EPA's cost analysis for total annualized present value costs, PWS 
costs, State/Primacy agency costs, and non-quantified costs.
1. Total Annualized Present Value Costs
    Tables VI.D-1 and VI.D-2 summarize the average annualized costs for 
the Stage 2 DBPR Preferred Regulatory Alternative at 3 and 7 percent 
discount rates, respectively. System costs range from approximately $55 
to $101 million annually at a 3 percent discount rate, with a mean 
estimate of approximately $77 million per year. The mean and range of 
annualized costs are similar at a 7 percent discount rate. State costs 
are estimated to be between $1.70 and $1.71 million per year depending 
on the discount rate. These estimates are annualized starting with the 
year of promulgation. Actual dollar costs during years when most 
treatment changes are expected to occur would be somewhat higher (the 
same is true for benefits that occur in the future).
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2. PWS costs
    PWS costs for the Stage 2 DBPR include non-treatment costs of rule 
implementation, Initial Distribution System Evaluations (IDSEs), Stage 
2 DBPR monitoring plans, additional routine monitoring, and operational 
evaluations. Systems required to install treatment to comply with the 
MCLs will accrue the additional costs of treatment installation as well 
as operation and maintenance. Significant PWS costs for IDSEs, 
treatment, and monitoring are described in this section, along with a 
sensitivity analysis.
    a. IDSE costs. Costs and burden associated with IDSE activities 
differ depending on whether or not the system performs the IDSE and, if 
so, which option a system chooses. All systems performing the IDSE are 
expected to incur some costs. EPA's analysis allocated systems into 
five categories to determine the costs of the IDSE--those conducting 
standard monitoring, SSS, VSS, 40/30, and NTNCWS not required to do an 
IDSE. EPA then developed cost estimates for each option. Tables VI.D-3, 
VI.D-4, and VI.D-5 illustrate PWS costs for IDSE for systems conducting 
an SMP, SSS, and 40/30, respectively.
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    b. PWS treatment costs. The number of plants changing treatment as 
a result of the Stage 2 DBPR and which technology various systems will 
install are determined from the compliance forecast. The percent of 
systems predicted to make treatment technology changes and the 
technologies predicted to be in place after implementation of the Stage 
2 DBPR are shown in Table VI.D-6. The cost model includes estimates for 
the cost of each technology; the results of the cost model for PWS 
treatment costs are summarized in Table VI.D-7.

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    c. Monitoring costs. Because systems already sample for the Stage 1 
DBPR, costs for additional routine monitoring are determined by the 
change in the number of samples to be collected from the Stage 1 to the 
Stage 2 DBPR. The

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Stage 2 DBPR monitoring requirements for systems are based only on 
population served and source water type, while the Stage 1 DBPR 
requirements are also based on the number of treatment plants. With 
this modification in monitoring scheme, the average system will have no 
change in monitoring costs. The number of samples required is estimated 
to increase for some systems but actually decrease from the Stage 1 to 
the Stage 2 DBPR for many systems. Table VI.D-8 summarizes the 
estimated additional routine monitoring costs for systems.
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3. State/Primacy Agency Costs
    To estimate State/Primacy Agency costs, the estimated number of 
full-time equivalents (FTEs) required per activity is multiplied by the 
number of labor hours per FTE, the State/Primacy Agency hourly wage, 
and the number of States/Primacy Agencies. EPA estimated the number of 
FTEs required per activity based on experience implementing previous 
rules, such as the Stage 1 DBPR. State/Primacy Agency costs are 
summarized in Table VI.D-9.
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4. Non-quantified Costs
    All significant costs that EPA has identified have been quantified. 
In some instances, EPA did not include a potential cost element because 
its effects are relatively minor and difficult to estimate. For 
example, it may be less costly for a small system to merge with 
neighboring systems than to add advanced treatment. Such changes have 
both costs (legal fees and connecting infrastructure) and benefits 
(economies of scale). Likewise, procuring a new source of water would 
have costs for new infrastructure, but could result in lower treatment 
costs. Operational costs such as changing storage tank operation were 
also not considered as alternatives to treatment. These might be 
options for systems with a single problem area with a long residence 
time. In the absence of detailed information needed to evaluate 
situations such as these, EPA has included a discussion of possible 
effects where appropriate. In general, however, the expected net effect 
of such situations is lower costs to PWSs. Thus, the EA tends to 
present conservatively high estimates of costs in relation to non-
quantified costs.

E. Household Costs of the Stage 2 DBPR

    EPA estimates that, as a whole, households subject to the Stage 2 
DBPR face minimal increases in their annual costs. Approximately 86 
percent of the households potentially subject to the rule are served by 
systems serving at least 10,000 people; these systems experience the 
lowest increases in costs due to significant economies of scale. 
Households served by small systems that add treatment will face the 
greatest increases in annual costs. Table VI.E-1 summarizes annual 
household cost increases for all system sizes.

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                                                     Table VI.E-1.--Annual Household Cost Increases.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                 Percentage   Percentage
                                                                                            Median        90th         95th      of annual    of annual
                                                             Total number   Mean annual     annual     percentile   percentile   household    household
                                                             of households   household    household      annual       annual        cost         cost
                                                                served          cost         cost      household    household    increase <   increase <
                                                                              increase     increase       cost         cost         $12          $120
                                                                                                        increase     increase    (percent)    (percent)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Households Served by All Plants
--------------------------------------------------------------------------------------------------------------------------------------------------------
All Systems...............................................     101,553,868        $0.62        $0.03        $0.36        $0.98           99          100
All Small Systems.........................................      14,261,241         2.20         0.10         0.79         2.57           97          100
SW < 10,000...............................................       3,251,893         4.58         0.79         2.69         7.24           95           99
SW >= 10,000..............................................      62,137,350         0.46         0.02         0.35         1.81           99          100
GW < 10,000...............................................      11,009,348         1.49         0.02         0.39         0.99           98          100
GW >= 10,000..............................................      25,155,277         0.13         0.00         0.03         0.08          100          100
-----------------------------------------------------------
                                                      Households Served by Plants Adding Treatment
--------------------------------------------------------------------------------------------------------------------------------------------------------
All Systems...............................................      10,161,304        $5.53        $0.80       $10.04       $22.40           92           99
All Small Systems.........................................         591,623        46.48        18.47       168.85       197.62           38           89
SW < 10,000...............................................         285,911        43.05        13.79       173.53       177.93           47           85
SW >= 10,000..............................................       9,060,119         2.83         0.80         6.98        11.31           96          100
GW < 10,000...............................................         305,712        49.69        16.65       109.86       197.62           31           92
GW >= 10,000..............................................         509,562         5.97         1.37        26.82        33.84           79          100
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: Detail may not add to total due to independent rounding. Number of households served by systems adding treatment will be higher than households
  served by plants adding treatment because an entire system will incur costs even if only some of the plants for that system add treatment (this would
  result in lower household costs, however).
 
Source: Exhibit 7.15, USEPA 2005a.

F. Incremental Costs and Benefits of the Stage 2 DBPR

    Incremental costs and benefits are those that are incurred or 
realized in reducing DBP exposures from one alternative to the next 
more stringent alternative. Estimates of incremental costs and benefits 
are useful in considering the economic efficiency of different 
regulatory options considered by the Agency. Generally, the goal of an 
incremental analysis is to identify the regulatory option where net 
social benefits are maximized. However, the usefulness of this analysis 
is constrained when major benefits and/or costs are not quantified or 
not monetized. Also, as pointed out by the Environmental Economics 
Advisory Committee of the Science Advisory Board, efficiency is not the 
only appropriate criterion for social decision making (USEPA 2000i).
    For the proposed Stage 2 DBPR, presentation of incremental 
quantitative benefit and cost comparisons may be unrepresentative of 
the true net benefits of the rule because a significant portion of the 
rule's potential benefits are not quantified, particularly potential 
reproductive and developmental health effects (see Section VI.C). Table 
VI.F-1 shows the incremental monetized costs and benefits for each 
regulatory alternative. Evaluation of this table shows that incremental 
costs generally fall within the range of incremental benefits for each 
more stringent alternative. Equally important, the addition of any 
benefits attributable to the non-quantified categories would add to the 
benefits without any increase in costs.
    Table VI.F-1 shows that the Preferred Alternative is the least-cost 
alternative. A comparison of Alternative 1 with the Preferred 
Alternative shows that Alternative 1 would have approximately the same 
benefits as the Preferred Alternative. The costs of Alternative 1 are 
greater due to the additional control of bromate. However, the benefits 
of Alternative 1 are less than the Preferred Alternative because the 
Agency is not able to estimate the additional benefits of reducing the 
bromate MCL. Alternative 1 was determined to be unacceptable due to the 
potential for increased risk of microbial exposure. Both benefits and 
costs are greater for Alternative 2 and Alternative 3 as compared to 
the Preferred Alternative. However, these regulatory alternatives do 
not have the risk-targeted design of the Preferred Alternative. Rather, 
implementation of these stringent standards would require a large 
number of systems to change treatment technology. The high costs of 
these regulatory alternatives and the drastic shift in the nation's 
drinking water practices were considered unwarranted at this time. (See 
Section VI.A of this preamble for a description of regulatory 
alternatives.)

                                            Table VI.F-1.--Incremental Costs and Benefits of the Stage 2 DBPR
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Annual       Annual      Incremental costs     Incremental benefits     Incremental net
 WTP for non-fatal bladder cancer                             costs       benefits  ----------------------------------------------        benefits
               cases                   Rule alternative   --------------------------                                              ----------------------
                                                                A            B                 C                      D                    E=D-C
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 3 Percent Discount Rate
--------------------------------------------------------------------------------------------------------------------------------------------------------
Lymphoma..........................  Preferred............          $79       $1,531  $79..................  $1,531...............  $1,452
                                    Alternative 1 \1\....          254        1,377  (\1\)................  (\1\)................  (\1\)
                                    Alternative 2........          422        5,167  343..................  3,637................  3,294
                                    Alternative 3........          634        7,130  212..................  1,962................  1,750
Bronchitis........................  Preferred............           79          763  79...................  763..................  684

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                                    Alternative 1 \1\....          254          686  (\1\)................  (\1\)................  (\1\)
                                    Alternative 2........          422        2,575  343..................  1,812................  1,469
                                    Alternative 3........          634        3,552  212..................  978..................  765
-----------------------------------
                                                                 7 Percent Discount Rate
--------------------------------------------------------------------------------------------------------------------------------------------------------
Lymphoma..........................  Preferred............          $77       $1,246  $77..................  $1,246...............  $1,170
                                    Alternative 1 \1\....          242        1,126  (\1\)................  (\1\)................  (\1\)
                                    Alternative 2........          406        4,227  330..................  2,981................  2,651
                                    Alternative 3........          613        5,832  207..................  1,605................  1,399
Bronchitis........................  Preferred............           77          621  77...................  621..................  544
                                    Alternative 1 \1\....          242          561  (\1\)................  (\1\)................  (\1\)
                                    Alternative 2........          406        2,105  330..................  1,484................  1,154
                                    Alternative 3........          613        2,904  207..................  799..................  593
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: Estimates are discounted to 2003 and given in 2003 dollars. Based on TTHM as an indicator, Villanueva et al. (2003) for baseline risk, and
  smoking/lung cancer cessation lag model. Assumes 26 percent of cases are fatal, 74 percent are non-fatal (USEPA 1999b). EPA recognizes that benefits
  may be as low as zero since causality has not yet been established between exposure to chlorinated water and bladder cancer.
 
 \1\ Alternative 1 appears to have fewer benefits than the Preferred Alternative because it does not incorporate the IDSE, as explained in Chapter 4.
  Furthermore, this EA does not quantify the benefits of reducing the MCL for bromate (and potentially associated cancer cases), a requirement that is
  included only in Alternative 1. This means that Alternative 1 is dominated by the Preferred Alternative in this analysis (having higher costs than the
  Preferred Alternative but lower benefits), and so it is not included in the incremental comparison of alternatives (Columns C-E). OMB states this in
  terms of comparing cost effectiveness ratios, but the same rule applies to an incremental cost, benefits, or net benefits comparison: ``When
  constructing and comparing incremental cost-effectiveness ratios, [analysts] * * * should make sure that inferior alternatives identified by the
  principles of strong and weak dominance are eliminated from consideration.'' (OMB Circular A-4, p. 10)
 
 Source: Exhibit 9.13, USEPA 2005a.

G. Benefits From the Reduction of Co-occurring Contaminants

    Installing certain advanced technologies to control DBPs has the 
added benefit of controlling other drinking water contaminants in 
addition to those specifically targeted by the Stage 2 DBPR. For 
example, membrane technology installed to reduce DBP precursors can 
also reduce or eliminate many other drinking water contaminants 
(depending on pore size), including those that EPA may regulate in the 
future. Removal of any contaminants that may face regulation could 
result in future cost savings to a water system. Because of the 
difficulties in establishing which systems would be affected by other 
current or future rules, no estimate was made of the potential cost 
savings from addressing more than one contaminant simultaneously.

H. Potential Risks From Other Contaminants

    Along with the reduction in DBPs from chlorination such as TTHM and 
HAA5 as a resultof the Stage 2 DBPR, there may be increases in other 
DBPs as systems switch from chlorine to alternative disinfectants. For 
all disinfectants, many DBPs are not regulated and many others have not 
yet been identified. EPA will continue to review new studies on DBPs 
and their occurrence levels to determine if they pose possible health 
risks. EPA continues to support regulation of TTHM and HAA5 as 
indicators for chlorination DBP occurrence and believes that 
operational and treatment changes made because of the Stage 2 DBPR will 
result in an overall decrease in risk.
1. Emerging DBPs
    Iodo-DBPs and nitrogenous DBPs including halonitromethanes are DBPs 
that have recently been reported (Richardson et al. 2002, Richardson 
2003). One recent occurrence study sampled quarterly at twelve surface 
water plants using different disinfectants across the U.S. for several 
iodo-THMs and halonitromethane species (Weinberg et al. 2002). The 
concentrations of iodo-THMs and halonitromethane in the majority of 
samples in this study were less than the analytical minimum reporting 
levels; plant-average concentrations of iodo-THM and halonitromethane 
species were typically less than 0.002 mg/L, which is an order of 
magnitude lower than the corresponding average concentrations of TTHM 
and HAA5 at those same plants. Chloropicrin, a halonitromethane 
species, was also measured in the ICR with a median concentration of 
0.00019 mg/L across all surface water samples. No occurrence data exist 
for the iodoacids due to the lack of a quantitative method and 
standards. Further work on chemical formation of iodo-DBPs and 
halonitromethanes is needed.
    Iodoacetic acid was found to be cytotoxic and genotoxic in 
Salmonella and mammalian cells (Plewa et al. 2004a) as were some of the 
halonitromethanes (Kundu et al. 2004; Plewa et al. 2004b). Although 
potent in these in vitro screening studies, further research is needed 
to determine if these DBPs are active in living systems. No conclusions 
on human health risk can be drawn from such preliminary studies.
2. N-Nitrosamines
    Another group of nitrogenous DBPs are the N-nitrosamines. A number 
of N-nitrosamines exist, and N-nitrosodimethylamine (NDMA), a probable 
human carcinogen (USEPA 1993), has been identified as a potential 
health risk in drinking water. NDMA is a contaminant from industrial 
sources and a potential disinfection byproduct from reactions of 
chlorine or chloramine with nitrogen containing organic matter and from 
some polymers used as coagulant aids. Studies have produced new 
information on the mechanism of formation of NDMA, but there is not 
enough information at this time to draw conclusions regarding a 
potential increase in NDMA occurrence as systems change treatment. 
Although there are studies that examined the occurrence of NDMA in some 
water systems, there are no systematic evaluations of the occurrence of 
NDMA and other nitrosamines in U.S. waters.

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Recent studies have provided new occurrence information that shows NDMA 
forms in both chlorinated and chloraminated systems. Barrett et al. 
(2003) reported median concentrations of less than 2ng/L for the seven 
chlorine systems studied and less than 3 ng/L for 13 chloramine 
systems. Another study demonstrated that factors other than 
disinfectant type may play an important role in the formation of NDMA 
(Schreiber and Mitch 2005). More research is underway to determine the 
extent of NDMA occurrence in drinking water systems. EPA has proposed 
monitoring for NDMA under Unregulated Contaminant Monitoring Rule 2 (70 
FR 49094, at 49103, August 22, 2005) (USEPA 2005m).
    Risk assessments have estimated that the 10-\6\ lifetime 
cancer risk level is 7 ng/L based on induction of tumors at multiple 
sites. NDMA is also present in food, tobacco smoke, and industrial 
emissions, and additional research is underway to determine the 
relative exposure of NDMA in drinking water to these other sources.
3. Other DBPs
    Some systems, depending on bromide and organic precursor levels in 
the source water and technology selection, may experience a shift to 
higher ratios, or concentrations, of brominated DBPs while the overall 
TTHM or HAA5 concentration may decrease. In some instances where 
alternative disinfectants are used, levels of chlorite and bromate may 
increase as a result of systems switching to chlorine dioxide or ozone, 
respectively. However, EPA anticipates that changes in chlorite and 
bromate concentration as a result of the Stage 2 DBPR will be minimal 
(USEPA 2005a). For most systems, overall levels of DBPs, as well as 
brominated DBP species, should decrease as a result of this rule. EPA 
continues to believe that precursor removal is a highly effective 
strategy to reduce levels of DBPs.
    EPA also considered the impact this rule may have on microbial 
contamination that may result from altering disinfection practices. To 
address this concern, the Agency developed this rule jointly with the 
Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR). EPA 
expects that the LT2ESWTR provisions will prevent increases in 
microbial risk resulting from the Stage 2 DBPR.

I. Effects of the Contaminant on the General Population and Groups 
Within the General Population That Are Identified As Likely To Be at 
Greater Risk of Adverse Health Effects

    EPA's Office of Water has historically considered risks to 
sensitive subpopulations (including fetuses, infants, and children) 
when establishing drinking water assessments, advisories and other 
guidance, and standards (USEPA 1989) (56 FR 3526, January 30, 1991) 
(USEPA 1991). In the case of Stage 2 DBPR, maximizing health protection 
for sensitive subpopulations requires balancing risks to achieve the 
recognized benefits of controlling waterborne pathogens while 
minimizing risk of potential DBP toxicity. Experience shows that 
waterborne disease from pathogens in drinking water is a major concern 
for children and other subgroups (e.g., the elderly, immunocompromised, 
and pregnant women) because of their greater vulnerabilities (Gerba et 
al. 1996). EPA believes DBPs may also potentially pose risks to fetuses 
and pregnant women (USEPA 1998a). In addition, because the elderly 
population (age 65 and above) is naturally at a higher risk of 
developing bladder cancer, their health risks may further increase as a 
result of long-term DBP exposure (National Cancer Institute 2002).
    In developing this rule, risks to sensitive subpopulations, 
including children, were taken into account in the assessments of 
disinfectants and DBPs. More details on sensitive subpopulations can be 
found in the Economic Analysis (USEPA 2005a). For each of the DBPs 
included in the Stage 2 DBPR, the maximum contaminant level goals 
(MCLG) are derived using the most sensitive endpoint among all 
available data and an intraspecies uncertainty factor of 10 which 
accounts for human variability including sensitive subpopulations, like 
children. The Agency has evaluated several alternative regulatory 
options and selected the one that balances cost with significant 
benefits, including those for sensitive subpopulations. The Stage 2 
DBPR will result in a potential reduction in cancer risk and a 
potential reduction in reproductive and developmental risk to fetuses 
and pregnant women. It should be noted that the LT2ESWTR, which 
accompanies this rule, reduces pathogens in drinking water and further 
protects sensitive subpopulations. See Section VII.G for a discussion 
of EPA's requirements under Executive Order 13045.

J. Uncertainties in the Risk, Benefit, and Cost Estimates for the Stage 
2 DBPR

    For today's final rule, EPA has estimated the current baseline risk 
from exposure to DBPs in drinking water and projected the risk 
reduction and cost for various rule alternatives. There is uncertainty 
in the risk calculation, the benefit estimates, the cost estimates, and 
the interaction with other regulations. The EA has an extensive 
discussion of relevant uncertainties (USEPA 2005a). This section 
briefly summarizes the major uncertainties. Table VI.J-1 presents a 
summary of uncertainty in the cost and benefit estimates, refers to the 
section or appendix of the EA where the information is introduced, and 
estimates the potential effects that each may have on national cost and 
benefit estimates.
    EPA believes that uncertainty in the compliance forecast has a 
potentially large influence on cost and benefit estimates for today's 
rule. Thus, the Agency has attempted to quantify the uncertainty by 
giving equal weight to two different compliance forecast approaches. 
One compliance forecast approach is based on the SWAT predictions, and 
the other is based on the ``ICR Matrix Method.'' The ICR Matrix Method 
uses the same basic approach as SWAT, but uses TTHM and HAA5 data from 
the ICR directly to estimate the percent of plants changing technology 
to comply with the Stage 2 DBPR and the resulting DBP reduction. To 
characterize the uncertainty of the compliance forecast results, EPA 
assumes a uniform distribution between SWAT and ICR Matrix Method 
results (USEPA 2005a). That is, the cost and benefit estimates 
presented in the preamble represent the midpoint between costs and 
benefits estimated using the SWAT model, and those estimated using the 
ICR Matrix Method. Cost estimates using the SWAT model are about 25% 
lower than the midpoint estimates, while those using the ICR Matrix 
Method are about 25% higher. Benefits estimated using the SWAT model 
are about 30% lower than the midpoint estimates, while those using the 
ICR Matrix Method are about 30% higher.
    EPA believes the compliance forecast may be overstated because the 
technology decision tree does not consider low-cost, non-treatment 
system improvements that could be used to comply with the Stage 2 DBPR. 
These improvements, including things like flushing more frequently and 
managing storage facilities to reduce water age, could be used by 
systems to reduce TTHM and HAA5 levels for specific

[[Page 462]]

locations in their distribution system to meet Stage 2 DBPR MCLs. Thus, 
the standard compliance forecast method as developed during the M/DBP 
FACA (with a 20 percent safety margin) is a reasonable estimation. 
However, SWAT does not explicitly consider the IDSE. To address 
uncertainty in the impact of the IDSE on the compliance forecast, EPA 
revised the compliance forecast methodology, assigning equal 
probability to 20 and 25 percent operational safety margins. EPA 
believes the 25 percent safety margin is a reasonable high-end estimate 
of system response to account for the influences of the IDSE. EPA used 
a spatial variability analysis to determine the appropriate safety 
margin to use to estimate the impact of the IDSE on the compliance 
forecast.
    These alternative approaches for the compliance forecast estimate 
are used to represent a range of possible results and are incorporated 
into the cost and benefit models using Monte Carlo probability 
functions. EPA believes this approach helps inform the reader of the 
likely magnitude of the impact of the uncertainties.
    In addition to quantifying some uncertainties in the compliance 
forecasts, EPA has explicitly accounted for uncertainty in estimated 
treatment technology costs. Treatment costs are modeled using a 
triangular distribution of  30 percent for Capital, and 
 15 percent for O&M costs to recognize that the assumptions 
for cost analysis to produce the national average are uncertain.
    For the cost estimates, uncertainty also exists in baseline data 
inputs, such as the total number of disinfecting plants and their 
typical average and design flow rates. Other cost model inputs such as 
labor rates and laboratory fees also contain uncertainties. In these 
cases, EPA has evaluated available data and estimated a cost input 
value to represent the average of all water systems nationally. EPA 
recognizes that there is uncertainty in this average and variability in 
the characteristics of individual systems. The influence of these 
uncertainties on national cost estimates is expected to be fairly 
minor.
    For the benefits estimates, uncertainty exists in model inputs such 
as the estimated PAR values and the cessation lag models. EPA 
considered three approaches to estimate attributable risk: (1) a range 
of risk derived from individual studies, (2) a risk estimate from a 
meta-analysis, and (3) a risk estimate from a pooled analysis. To 
quantify uncertainty in cessation lag, three independent cessation lag 
models derived from three different epidemiological studies are used. 
Also, two functional forms are used for each of these data sets and 
uncertainty in the parameters of those functions is included in the 
analysis. As noted previously, causality has not been established 
between DBP levels and cancer endpoints, so the lower bound of 
potential risk reductions may be as low as zero.
    In a number of different contexts over the past few years, the 
Agency has considered the relative merits and assumptions encountered 
when employing meta-analyses. Cessation lag modeling is a relatively 
recent analysis that the Agency has incorporated into its risk analyses 
to more appropriately model the timing of health benefits. The specific 
papers upon which the Stage 2 analysis is based have been peer 
reviewed. However, the Agency believes that it is time to consider 
these Agency-wide science issues in a broader sense with outside 
experts to better inform the Agency's future analyses.
    For monetization of benefits, EPA uses two alternatives for valuing 
non-fatal bladder cancer. Other uncertainties, such as the linear 
relationship between DBP reductions and reductions in bladder cancer 
cases avoided, are discussed qualitatively.
    In addition to the uncertainties quantified as part of the benefits 
evaluation, other uncertainties that have not been quantified could 
result in either an over-or under-estimation of the benefits. Two of 
the greatest uncertainties affecting the benefits of the Stage 2 DBPR, 
benefits from potential reductions of cancers other than bladder and 
benefits from possible reductions in potential reproductive and 
developmental health effects, are unquantified. Both of these factors 
could result in an underestimation of quantified Stage 2 DBPR benefits.

                                              Table VI.J-1.--Effects of Uncertainties on National Estimates
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                 Section with            Potential effect on benefit estimate                  Potential effect on cost estimates
 Assumptions for which there    full discussion --------------------------------------------------------------------------------------------------------
        is uncertainty          of uncertainty    Under-estimate     Over-estimate    Unknown impact    Under-estimate   Over-estimate    Unknown impact
--------------------------------------------------------------------------------------------------------------------------------------------------------
Uncertainty in the industry    3.4.............  ................  ................  X...............  ...............  ...............  X
 baseline (SDWIS and 1995
 CWSS data).
Uncertainty in observed data   3.7.............  ................  ................  X...............  ...............  ...............  X
 and predictive tools used to
 characterize DBP occurrence
 for the pre-Stage 1 baseline.
Uncertainty in predictive      Chapter 5,         Quantified in primary analysis (addresses potential
 tools used to develop the      Appendix A.                  underestimate or overestimate)
 compliance forecast for
 surface water systems (SWAT
 and ICR Matrix Method).
                                Quantified in primary analysis (addresses potential
                                           underestimate or overestimate)
Uncertainty in ground water    Chapter 5, A and  ................  ................  X...............  ...............  ...............  X
 compliance forecast            B.
 methodologies.
Operational safety margin of   5.2.............  ................  ................  X...............  ...............  ...............  X
 20%.
Impacts of the IDSE on the     5.3.............      Quantified in the primary analysis (addresses
 compliance forecast for the                                    potential underestimate)
 Preferred Regulatory
 Alternative.
                                   Quantified in the primary analysis (addresses
                                              potential underestimate)

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Uncertainty in the PAR value.  6.1.1 Appendix E   Quantified in the primary analysis (addresses range
                                                    of potential effects, but true values could lie
                                                                     outside range)
Reduction in TTHM and HAA5     6.3.3...........  ................  ................  X...............
 used as proxies for all
 chlorination DBPs.
DBPs have a linear no-         6.2.1...........  ................  X...............
 threshold dose-response
 relationship for bladder
 cancer effects.
Uncertainty in benefits        6.5.2...........      Quantified in the primary analysis (addresses
 valuation inputs.                                      potential underestimate or overestimate)
Benefits of reduced cancers    6.7.............     Quantified in a sensitivity analysis (addresses
 other than bladder cancer                                      potential underestimate)
 are not included in the
 quantitative analysis.
Value of potential             6.8.............  X...............
 reproductive and
 developmental health effects
 avoided is not quantified in
 the primary analysis.
Treatment costs do not         7.4.1...........  ................  ................  ................  X..............
 include costs for minor
 operational changes
 predicted by SWAT.
Median operational and water   7.4.1...........  ................  ................  ................  ...............  ...............  X
 quality parameters
 considered for technology
 unit costs.
Economies of scale for         7.4.1...........  ................  ................  ................  ...............  X..............
 combination treatment
 technologies not considered.
Possible UV-chloramine         7.4.1...........  ................  ................  ................  ...............  X..............
 synergy not taken into
 account.
Potential low-cost             7.4.2...........  ................  ................  ................  ...............  X..............
 alternatives to treatment
 not considered.
Uncertainties in unit costs..  7.4.3...........  ................  ................  ................      Quantified in primary analysis (addresses
                                                                                                            potential overestimate or underestimate)
--------------------------------------------------------------------------------------------------------------------------------------------------------

K. Benefit/Cost Determination for the Stage 2 DBPR

    The Agency has determined that the benefits of the Stage 2 DBPR 
justify the costs. As discussed previously, the main concern for the 
Agency and the Advisory Committee involved in the Stage 2 rulemaking 
process was to provide more equitable protection from DBPs across the 
entire distribution system and reduce high DBP levels. The final rule 
achieves this objective using the least cost alternative by targeting 
sampling locations with high DBP levels and modifying how the annual 
average DBP level is calculated. This will reduce both average DBP 
levels associated with bladder cancer (and possibly other cancers) and 
peak DBP levels which are potentially associated with reproductive and 
developmental effects. In addition, this rule may reduce uncertainty 
about drinking water quality and may allow some systems to avoid 
installing additional technology to meet future drinking water 
regulations.
    Table VI.K-1 presents net benefits for the four regulatory 
alternatives evaluated by EPA. This table shows that net benefits are 
positive for all four regulatory alternatives. Generally, analysis of 
net benefits is used to identify alternatives where benefits exceed 
costs, as well as the alternative that maximizes net benefits. However, 
analyses of net benefits should consider both quantified and non-
quantified (where possible) benefits and costs. As discussed previously 
with incremental net benefits, the usefulness of this analysis in 
evaluating regulatory alternatives for the Stage 2 DBPR is somewhat 
limited because many benefits from this rule are non-quantified and 
non-monetized.
    Table VI.K-1 shows that the Preferred Alternative is the least cost 
alternative. The Preferred Alternative has higher mean net benefits 
than Alternative 1. Alternatives 2 and 3 have higher benefits than the 
Preferred Alternative but also much greater costs. These regulatory 
alternatives do not have the risk-targeted design of the Preferred 
Alternative. Rather, a large number of systems would be required to 
make treatment technology changes to meet the stringent standards under 
these regulatory alternatives. Also, because causality has not been 
established between DBP exposure and bladder cancer, actual benefits 
may be as low as zero. EPA is promulgating the preferred regulatory 
alternative because the Agency believes that such a drastic shift in 
the nation's drinking water practices is not warranted at this time.

[[Page 464]]



                      Table VI.K-1.--Mean Net Benefits by Regulatory Alternative ($Million)
----------------------------------------------------------------------------------------------------------------
                                            WTP for non-fatal       Mean annual     Mean annual      Mean net
           Rule alternative               bladder cancer cases         costs         benefits        benefits
----------------------------------------------------------------------------------------------------------------
                                        3 Percent Discount Rate, 25 Years
----------------------------------------------------------------------------------------------------------------
Preferred.............................  Lymphoma................           $78.8        $1,530.8          $1,452
A1....................................  ........................           254.1         1,376.6           1,122
A2....................................  ........................           421.7         5,167.4           4,746
A3....................................  ........................           634.2         7,129.6           6,495
Preferred.............................  Bronchitis..............            78.8           762.8             684
A1....................................  ........................           254.1           685.9             432
A2....................................  ........................           421.7         2,574.6           2,153
A3....................................  ........................           634.2         3,552.2           2,918
---------------------------------------
                                        7 Percent Discount Rate, 25 Years
----------------------------------------------------------------------------------------------------------------
Preferred.............................  Lymphoma................           $76.8        $1,246.5          $1,170
A1....................................  ........................           241.8         1,126.4             885
A2....................................  ........................           406.4         4,227.2           3,821
A3....................................  ........................           613.1         5,832.4           5,219
Preferred.............................  Bronchitis..............            76.8           620.7             544
A1....................................  ........................           241.8           560.8             319
A2....................................  ........................           406.4         2,104.6           1,698
A3....................................  ........................           613.1         2,903.8          2,291
----------------------------------------------------------------------------------------------------------------
Notes: Estimates are discounted to 2003 and given in 2003 dollars. Based on TTHM as an indicator, Villanueva et
  al. (2003) for baseline risk, and smoking/lung cancer cessation lag model. Assumes 26 percent of cases are
  fatal, 74 percent are non-fatal (USEPA 1999b). EPA recognizes that benefits may be as low as zero since
  causality has not yet been established exposure to chlorinated water and bladder cancer.
 
 Source: Exhibits 9.10 and 9.11, USEPA 2005a.

    The Agency also compared the costs and benefits for each regulatory 
alternative by calculating which option is the most cost-effective. The 
cost-effectiveness analysis compares the cost of the rule per bladder 
cancer case avoided. This cost-effectiveness measure is another way of 
examining the benefits and costs of the rule, but should not be used to 
compare alternatives because an alternative with the lowest cost per 
illness/death avoided may not result in the highest net benefits. Table 
VI.K-2 shows the cost of the rule per case avoided. This table shows 
that cost per case avoided for the preferred alternative seems 
favorable when compared to the willingness to pay estimates. Additional 
information about this analysis and other methods of comparing benefits 
and costs can be found in the EA (USEPA 2005a).

 Table VI.K-2.--Estimated Cost Per Discounted Cased Avoided \1\ for the
  Regulatory Alternatives, Using TTHM as DBP Indicator and Smoking/Lung
              Cancer Cessation Lag Model ($Millions, 2003)
------------------------------------------------------------------------
                                                Cost per case avoided
             Rule alternative              -----------------------------
                                                  3%             7%
------------------------------------------------------------------------
Preferred.................................          $.033          $.041
Alternative 1.............................          1.18           1.42
Alternative 2.............................          0.52           0.63
Alternative 3.............................          0.57           0.69
------------------------------------------------------------------------
\1\ The cost effectiveness ratios are a potentially a high estimate
  because regulatory costs in the numerator are not adjusted by
  subtracting the avoided medical costs associated with cases avoided to
  produce a net cost numerator. Subtraction of theses costs would not be
  expected to alter the ranking of alternatives. In the case where
  thresholds of maximum public expenditure per case avoided are
  prescribed, defining the numerator more precisely by making such
  adjustments would be appropriate.
 
 Notes: In reference to conducting incremental CEA, OMB states that
  analyst should make sure that ``When constructing and comparing
  incremental cost-effectiveness ratios, [analysts] should make sure
  that inferior alternatives identified by the principles of strong and
  weak dominance are eliminated from consideration'' (OMB Circular A-4,
  p. 10). Alternative 1 is dominated by the Preferred Alternative and is
  therefore not included in the incremental analysis. The reason for
  this domination is mainly that the Preferred Alternative includes IDSE
  and Alternative 1 does not; and to a lesser degree because the bromate
  control included in Alternative 1 increases the costs but the benefits
  of this control are not quantified at this time. Alternative 2 is
  compared directly to the Preferred Alternative (skipping Alternative
  1) in this analysis. Cost per case avoided is in year 2003 dollars
  ($Millions), discounted for the 25 year analysis period to year 2005.
 
 Source: Exhibit 9.14, USEPA, 2005a.

L. Summary of Major Comments

    EPA received significant public comment on the analysis of benefits 
and costs of the proposed Stage 2 DBPR in the following areas: 
interpretation of health effects studies, derivation of benefits, use 
of SWAT, illustrative example, unanticipated risk issues, and valuation 
of cancer cases avoided. The following discussion summarizes public 
comment in these areas and EPA's responses.
1. Interpretation of Health Effects Studies
    EPA requested comment on the conclusions of the cancer health 
effects section and the epidemiology and toxicology studies discussed. 
A number of comments questioned the overall

[[Page 465]]

interpretation of the studies presented by EPA. A few comments pointed 
out missed studies. Commenters also asked about concordance between 
cancer epidemiology and toxicology. Some commenters also felt EPA did 
not discuss the broad range of risks from DBPs other than the ones 
regulated.
    The Agency continues to believe that, although there is not a 
causal link, the cancer literature points to an association between 
bladder cancer and potentially rectal and colon cancer and exposure to 
chlorinated surface water. EPA has included in today's preamble the 
literature that commenters pointed out as missing and expands on its 
discussion of non-regulated DBPs.
    EPA believes that a lack of bladder cancer effect in toxicological 
studies does not negate the findings in epidemiological studies at this 
time. Tumor site concordance between human and test animal is not 
necessary to determine carcinogenic potential. While there is evidence 
from human cancer epidemiology studies that lifetime consumption of the 
DBP mixture within chlorinated surface water poses a bladder cancer 
risk, the specific causative constituents have not been identified. EPA 
will continue to evaluate new mode-of-action data as it becomes 
available.
    Several comments were received on EPA's characterization of the 
literature on reproductive and developmental health risk. Some 
commenters wanted EPA to characterize reproductive and developmental 
health effects more strongly, stating that current research shows more 
evidence for these effects than described in the proposed preamble. 
Others thought that EPA's characterization in the proposal was too 
strong, and that EPA had overemphasized these health concerns. Some 
commenters noted that certain published studies were missing from EPA's 
risk discussion.
    EPA believes that the characterization of reproductive and 
developmental risks in the final Stage 2 DBPR preamble is appropriate 
based on the weight of evidence evaluation of the reproductive and 
developmental epidemiology database described in Section III.C. EPA 
considered comments and incorporated additional and recent studies into 
its characterization of health risks in today's final preamble. While 
no causal link has been established, EPA's evaluation of the available 
studies continues to indicate a potential health hazard that warrants 
additional regulatory action beyond the Stage 1 DBPR. The 
inconsistencies and uncertainties remaining in the available science 
support the incremental nature of change in today's rule.
    EPA did not include all findings from every study in the proposed 
DBPR preamble because the intent was to provide a summary overview and 
more importantly, the Agency's conclusions regarding the weight of 
evidence. The epidemiology literature has inconsistencies in its 
findings on the relationship between various reproductive and 
developmental health effects and DBPs. In this final preamble, EPA 
describes how recent studies since the proposal further inform the 
perspective of overall risk from exposure to DBPs. EPA continues to 
believe that studies indicate a potential hazard.
2. Derivation of Benefits
    EPA received numerous comments on the derivation of benefits from 
occurrence estimates for the Stage 2 DBPR. The majority of the comments 
provided addressed EPA's use of a cessation lag model to estimate the 
timing of benefits and a PAR analysis to estimate reduced risks. 
Several commenters opposed the cessation lag model proposed by EPA, 
suggesting that EPA use a longer cessation lag period or conduct a 
sensitivity analysis on the cessation lag exponent.
    In the effort to develop a cessation lag model specific to DBPs, 
EPA reviewed the available epidemiological literature for information 
relating to the timing of exposure and response, but could not identify 
any studies that could, alone or in combination, support a specific 
cessation lag model for DBPs in drinking water. Thus, in keeping with 
the SAB recommendation to consider other models in the absence of 
specific cessation lag information (USEPA 2001d), EPA explored the use 
of information on other carcinogens that could be used to characterize 
the influence of cessation lag in calculating benefits. The benefit 
analysis for today's rule uses three cessation lag models, which allows 
for a better characterization of uncertainty than did the approach used 
in the proposal. More details on this analysis are in the EA (USEPA 
2005a).
    Additional comments were received on the use of PAR values derived 
from epidemiology studies to determine the number of bladder cancer 
cases attributable to DBP exposure. Some commenters remarked that there 
was not sufficient evidence in the epidemiology studies used to develop 
a reliable PAR estimate. A key issue expressed in the comments was that 
studies that developed the PAR estimates did not adequately control for 
confounders. One commenter supported EPA review of the Villanueva 
(2003) meta-analysis, stating that this was the best available data on 
the issue.
    EPA revised the methodology for calculating PAR values for bladder 
cancer associated with exposure to chlorinated drinking water by 
considering three different analytical approaches as described in 
Section V.B.2. EPA used the PAR values from all three approaches to 
estimate the number of bladder cancer cases ultimately avoided annually 
as a result of the Stage 2 DBPR. Taken together, the three approaches 
provide a reasonable estimate of the range of potential risk. For 
simplicity, EPA used the Villanueva et al. (2003) study to calculate 
the annual benefits of the rule. The benefit estimates derived from 
Villanueva et al. (2003) capture a substantial portion of the overall 
range of results, reflecting the uncertainty in both the underlying OR 
and PAR values, as well as the uncertainty in DBP reductions for Stage 
2. More details on the PAR analysis can be found in the EA (USEPA 
2005a).
3. Use of SWAT
    Comments received on the use of SWAT for the compliance forecast 
claimed that the model probably underestimates DBP occurrence levels 
and hence underestimates compliance costs. Other commenters supported 
EPA's occurrence estimation methods and results. Some commenters added 
that monitoring under the IDSE will produce different results than 
monitoring for the ICR and that SWAT did not capture these changes.
    EPA describes in detail the limitations of SWAT as well as all 
assumptions and uncertainties associated with the model in the EA 
published with today's rule. EPA believes that, for the reasons stated 
below, the standard compliance forecast method using SWAT, as developed 
during the M-DBP FACA, provides a reasonable prediction of national 
treatment changes and resulting DBP levels anticipated for the Stage 2 
DBPR:
    1. SWAT predictive equations for TTHM and HAA5 were calibrated to 
ICR-observed TTHM and HAA5 data.
    2. SWAT estimates are based on 12 months of influent water quality 
data, treatment train information, and related characteristics for the 
273 ICR surface water plants. EPA believes the ICR data provide a 
robust basis for the compliance forecast as it represents significant 
variability with respect to factors influencing DBP formation, 
including temperature, residence time, and geographical region.
    3. EPA uses a ``delta'' approach to reduce the impact of 
uncertainty in

[[Page 466]]

SWAT's predictive equations for TTHM and HAA5. Under this approach, EPA 
1) estimates the difference in technology and TTHM and HAA5 
concentration predictions between pre-Stage 1 and post-Stage 1; 2) 
estimates the difference in technology and TTHM and HAA5 concentration 
predictions between pre-Stage 1 and post-Stage 2; and 3) subtracts the 
result of the first estimate from the second estimate to predict the 
impacts between Stage 1 and Stage 2. Since each predictive estimate has 
bias in the same direction, EPA believes that this methodology 
minimized overall predictive error.
    In response to commenters concerns about potential uncertainties in 
the SWAT predictions, EPA also developed the ``ICR Matrix Method.'' The 
ICR Matrix Method uses TTHM and HAA5 data from the ICR to estimate the 
percent of plants changing technology to comply with the Stage 2 DBPR 
and the resulting DBP reduction. The EA includes a detailed description 
of the ICR Matrix Method (USEPA 2005a). In the analysis for today's 
rule, EPA gives equal weight to SWAT and ICR Matrix Method predictions 
in estimating Stage 2 compliance forecasts and resultant reductions in 
DBP exposure. The ICR Matrix Method is also used to estimate reductions 
in the occurrence of peak TTHM and HAA5 concentrations because SWAT-
predicted TTHM and HAA5 concentrations are valid only when considering 
national averages, not at the plant level.
    EPA revised the Stage 2 DBPR compliance forecast methodology to 
quantify the potential impacts of the IDSE for large and medium surface 
water systems. For these systems, EPA predicted compliance implications 
using a safety margin of both 20 and 25 percent based on an analysis of 
spatial variability in TTHM and HAA5 occurrence. EPA assigned equal 
probability to the 20 and 25 percent safety margins because both 
alternatives are considered equally plausible. These changes result in 
a wider uncertainty range for the compliance cost estimates than under 
the EA of the proposed rule. EPA assumes the 20 percent operational 
safety margin accounts for variability in small surface water systems 
and all ground water systems. Small systems are not expected to find 
significantly higher levels that affect their compliance as a result of 
the IDSE because their distribution systems are not as complex as large 
systems. Additionally, the IDSE is not expected to significantly impact 
the compliance forecast for ground water systems because they have more 
consistent source water quality and do not experience significant year-
to-year variability in TTHM and HAA5 occurrence.
    As some commenters noted, any underestimation in costs as a result 
of the compliance forecast is associated with an underestimation in the 
benefits. Accordingly, EPA adjusted both cost and benefits estimates 
based on the ICR Matrix Method and the impact of the IDSE for the upper 
end of the compliance forecast range.
4. Illustrative Example
    Many comments were received on the illustrative calculation of 
fetal loss benefits included in the proposed EA. Many commenters 
recommended that EPA remove this calculation because of uncertainties 
in the underlying data. Other commenters, however, expressed support 
for this calculation because of the magnitude of potential benefits, 
and suggested that EPA include these benefits in its primary analysis.
    EPA believes that the reproductive and developmental epidemiologic 
data, although not conclusive, are suggestive of potential health 
effects in humans exposed to DBPs. EPA does not believe the available 
evidence provides an adequate basis for quantifying potential 
reproductive and developmental risks. Nevertheless, given the 
widespread nature of exposure to DBPs, the importance our society 
places on reproductive and developmental health, and the large number 
of fetal losses experienced each year in the U.S. (nearly 1 million), 
the Agency believes that it is appropriate to provide some quantitative 
indication of the potential risk suggested by some of the published 
results on reproductive and developmental endpoints, despite the 
absence of certainty regarding a causal link between disinfection 
byproducts and these risks and the inconsistencies between studies. 
However, the Agency is unable at this time to either develop a specific 
estimate of the value of avoiding fetal loss or to use a benefit 
transfer methodology to estimate the value from studies that address 
other endpoints.
5. Unanticipated Risk Issues
    Comments were received that expressed concern about unanticipated 
risks that could result from the proposed Stage 2 DBPR. Several 
commenters remarked that regulation of TTHM and HAA5 would not control 
levels of other DBPs that may be more toxic than these indicator 
compounds, such as NDMA. Some commenters supported future research on 
the potential health effects of other DBPs. Other comments suggested 
that EPA further consider these risks when developing the final Stage 2 
DBPR.
    EPA has addressed the occurrence of other DBPs in Section VI.H of 
this document and in the EA (USEPA 2005a). Levels of some DBPs may 
increase because of treatment changes anticipated as a result of 
today's rule. However, these DBPs generally occur at much lower levels 
than TTHM and HAA5, often more than an order of magnitude less (USEPA 
2005f, Weinberg et al. 2002). For NDMA, studies have shown formation in 
both chlorinated and chloraminated systems (Barrett et al. 2003). The 
uncertainties surrounding NDMA formation make determinations regarding 
the impact of the Stage 2 DBPR difficult. In addition, other routes of 
exposure appear to be more significant than drinking water. Dietary 
sources of NDMA include preserved meat and fish products, beer and 
tobacco. EPA is looking at calculating the relative source contribution 
of these routes of exposure compared to drinking water.
    EPA continues to support the use of TTHM and HAA5 as indicators for 
DBP regulation. The presence of TTHM and HAA5 is representative of the 
occurrence of many other chlorination DBPs; thus, a reduction in the 
TTHM and HAA5 generally indicates an overall reduction of DBPs. EPA 
also supports additional research on unregulated and unknown DBPs to 
ensure continual public health protection.
6. Valuation of Cancer Cases Avoided
    A number of commenters remarked on the valuation of cancer cases 
avoided. Some commenters supported the use of value of statistical life 
(VSL) analysis in monetizing the benefits of fatal bladder cancer cases 
avoided. Comments were also received in support of the addition of 
expected medical costs for treating fatal bladder cancer cases to the 
VSL estimates. Other commenters recommended that EPA further review the 
use of willingness-to-pay estimates used to value the non-fatal cancer 
cases avoided. These comments stated concern over the similarity of 
bronchitis and lymphoma to bladder cancer and the resulting limitation 
of benefits transfer.
    EPA thanks commenters for expressing support of the use of VSL and 
valuation of fatal bladder cancer cases. EPA acknowledges that the 
willingness to pay (WTP) to avoid curable lymphoma or chronic 
bronchitis is not a perfect substitute for the WTP to avoid a case of 
non-fatal bladder cancer. However, non-fatal internal cancers, 
regardless of type, generally present patients with very similar

[[Page 467]]

treatment, health, and long-term quality of life implications, 
including surgery, radiation or chemotherapy treatments (with attendant 
side effects), and generally diminished vitality over the duration of 
the illness. In the absence of more specific WTP studies, EPA believes 
the WTP values for avoiding a case of curable lymphoma or a case of 
chronic bronchitis provides a reasonable, though not definitive, 
substitute for the value of avoiding non-fatal bladder cancer.

VII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review

    Under Executive Order 12866, [58 FR 51735, (October 4, 1993)] the 
Agency must determine whether the regulatory action is ``significant'' 
and therefore subject to OMB review and the requirements of the 
Executive Order. The Order defines ``significant regulatory action'' as 
one that is likely to result in a rule that may:
    (1) Have an annual effect on the economy of $100 million or more or 
adversely affect in a material way the economy, a sector of the 
economy, productivity, competition, jobs, the environment, public 
health or safety, or State, local, or Tribal governments or 
communities;
    (2) Create a serious inconsistency or otherwise interfere with an 
action taken or planned by another agency;
    (3) Materially alter the budgetary impact of entitlements, grants, 
user fees, or loan programs or the rights and obligations of recipients 
thereof; or
    (4) Raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the Executive Order.
    Pursuant to the terms of Executive Order 12866, it has been 
determined that this rule is a ``significant regulatory action.'' As 
such, this action was submitted to OMB for review. Changes made in 
response to OMB suggestions or recommendations will be documented in 
the public record.

B. Paperwork Reduction Act

    The Office of Management and Budget (OMB) has approved the 
information collection requirements contained in this rule under the 
provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. and 
has assigned OMB control number 2040-0265 (USEPA 2005n).
    The information collected as a result of this rule will allow the 
States and EPA to determine appropriate requirements for specific 
systems, and to evaluate compliance with the rule. For the first three 
years after Stage 2 DBPR promulgation, the major information 
requirements involve monitoring activities, which include conducting 
the IDSE and submission of the IDSE report, and tracking compliance. 
The information collection requirements are mandatory (Part 141), and 
the information collected is not confidential.
    The estimate of annual average burden hours for the Stage 2 DBPR 
for systems and States is 228,529 hours. This estimate covers the first 
three years of the Stage 2 DBPR and most of the IDSE (small system 
reports are not due until the fourth year). The annual average 
aggregate cost estimate is $9.8 million for operation and maintenance 
as a purchase of service for lab work and $6.6 million is associated 
with labor. The annual burden hour per response is 4.18 hours. The 
frequency of response (average responses per respondent) is 7.59 
annually. The estimated number of likely respondents is 7,202 per year 
(the product of burden hours per response, frequency, and respondents 
does not total the annual average burden hours due to rounding). 
Because disinfecting systems have already purchased basic monitoring 
equipment to comply with the Stage 1 DBPR, EPA assumes no capital 
start-up costs are associated with the Stage 2 DBPR ICR.
    Burden means the total time, effort, or financial resources 
expended by persons to generate, maintain, retain, or disclose or 
provide information to or for a Federal agency. This includes the time 
needed to review instructions; develop, acquire, install, and utilize 
technology and systems for the purposes of collecting, validating, and 
verifying information, processing and maintaining information, and 
disclosing and providing information; adjust the existing ways to 
comply with any previously applicable instructions and requirements; 
train personnel to be able to respond to a collection of information; 
search data sources; complete and review the collection of information; 
and transmit or otherwise disclose the information.
    An agency may not conduct or sponsor, and a person is not required 
to respond to a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for EPA's 
regulations in 40 CFR are listed in 40 CFR part 9. In addition, EPA is 
amending the table in 40 CFR part 9 of currently approved OMB control 
numbers for various regulations to list the regulatory citations for 
the information requirements contained in this final rule.

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency 
to prepare a regulatory flexibility analysis for any rule subject to 
notice and comment rulemaking requirements under the Administrative 
Procedure Act or other statute unless the agency certifies that the 
rule will not have a significant economic impact on a substantial 
number of small entities. Small entities include small businesses, 
small organizations, and small governmental jurisdictions.
    The RFA provides default definitions for each type of small entity. 
Small entities are defined as: (1) A small business as defined by the 
Small Business Administrations's (SBA) regulations at 13 CFR 121.201; 
(2) a small governmental jurisdiction that is a government of a city, 
county, town, school district or special district with a population of 
less than 50,000; and (3) a small organization that is any ``not-for-
profit enterprise which is independently owned and operated and is not 
dominant in its field.'' However, the RFA also authorizes an agency to 
use alternative definitions for each category of small entity, ``which 
are appropriate to the activities of the agency'' after proposing the 
alternative definition(s) in the Federal Register and taking comment. 5 
U.S.C. 601(3)-(5). In addition, to establish an alternative small 
business definition, agencies must consult with SBA's Chief Council for 
Advocacy.
    For purposes of assessing the impacts of today's rule on small 
entities, EPA considered small entities to be public water systems 
serving 10,000 or fewer persons. As required by the RFA, EPA proposed 
using this alternative definition in the Federal Register (63 FR 7620, 
February 13, 1998), requested public comment, consulted with the Small 
Business Administration (SBA), and finalized the alternative definition 
in the Consumer Confidence Reports regulation (63 FR 44511, August 19, 
1998). As stated in that Final Rule, the alternative definition is 
applied to this regulation as well.
    After considering the economic impacts of today's final rule on 
small entities, I certify that this action will not have a significant 
economic impact on a substantial number of small entities. The small 
entities regulated by this final rule are PWSs serving fewer than 
10,000 people. We have determined that 92 small surface water and 
ground water under the direct influence of surface water (GWUDI) 
systems (or 2.16% of all

[[Page 468]]

small surface water and GWUDI systems affected by the Stage 2 DBPR) 
will experience an impact of 1% or greater of average annual revenues. 
Of the 92, 40 small surface water and GWUDI systems (or 0.94% of all 
small surface water and GWUDI systems affected by the Stage 2 DBPR) 
will experience an impact of 3% or greater of average annual revenues. 
Further, 354 small ground water systems (or 1.02% of all small ground 
water systems affected by the Stage 2 DBPR) will experience an impact 
of 1% or greater of average annual revenues. Of the 354, 45 small 
ground water systems (or 0.13% of all small ground water systems 
affected by the Stage 2 DBPR) will experience an impact of 3% or 
greater of average annual revenues.
    Although this final rule will not have a significant economic 
impact on a substantial number of small entities, EPA nonetheless has 
tried to reduce the impact of this rule on small entities. The Stage 2 
DBPR contains a number of provisions to minimize the impact of the rule 
on systems generally, and on small systems in particular. For example, 
small systems have a longer time frame to comply with requirements than 
large systems (see Sec.  141.600(c) and Sec.  141.620(c)). The final 
rule determines monitoring frequency based on population rather than 
plant-based monitoring requirements (see Sec.  141.605 and Sec.  
141.621(a)) as proposed. Small systems will also have to take fewer 
samples than large systems due to the 40/30 waiver (see Sec.  
141.603(a)), for which small, ground water systems are expected to be 
able to qualify, and the very small system waiver (see Sec.  141.604).
    Funding may be available from programs administered by EPA and 
other Federal agencies to assist small PWSs in complying with the Stage 
2 DBPR. The Drinking Water State Revolving Fund (DWSRF) assists PWSs 
with financing the costs of infrastructure needed to achieve or 
maintain compliance with SDWA requirements. Through the DWSRF, EPA 
awards capitalization grants to States, which in turn can provide low-
cost loans and other types of assistance to eligible PWSs. Loans made 
under the program can have interest rates between 0 percent and market 
rate and repayment terms of up to 20 years. States prioritize funding 
based on projects that address the most serious risks to human health 
and assist PWSs most in need. Congress provided the DWSRF program $8 
billion for fiscal years 1997 through 2004.
    The DWSRF places an emphasis on small and disadvantaged 
communities. States must provide a minimum of 15% of the available 
funds for loans to small communities. A State has the option of 
providing up to 30% of the grant awarded to the State to furnish 
additional assistance to State-defined disadvantaged communities. This 
assistance can take the form of lower interest rates, principal 
forgiveness, or negative interest rate loans. The State may also extend 
repayment terms of loans for disadvantaged communities to up to 30 
years. A State can set aside up to 2% of the grant to provide technical 
assistance to PWSs serving communities with populations fewer than 
10,000.
    In addition to the DWSRF, money is available from the Department of 
Agriculture's Rural Utility Service (RUS) and Housing and Urban 
Development's Community Development Block Grant (CDBG) program. RUS 
provides loans, guaranteed loans, and grants to improve, repair, or 
construct water supply and distribution systems in rural areas and 
towns of up to 10,000 people. In fiscal year 2003, RUS had over $1.5 
billion of available funds for water and environmental programs. The 
CDBG program includes direct grants to States, which in turn are 
awarded to smaller communities, rural areas, and colo[ntilde]as in 
Arizona, California, New Mexico, and Texas and direct grants to U.S. 
territories and trusts. The CDBG budget for fiscal year 2003 totaled 
over $4.4 billion.
    Although not required by the RFA to convene a Small Business 
Advocacy Review (SBAR) Panel because EPA determined that the proposed 
rule would not have a significant economic impact on a substantial 
number of small entities, EPA did convene a panel to obtain advice and 
recommendations from representatives of the small entities potentially 
subject to this rule's requirements. For a description of the SBAR 
Panel and stakeholder recommendations, please see the proposed rule 
(USEPA 2003a).

D. Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public 
Law 104-4, establishes requirements for Federal agencies to assess the 
effects of their regulatory actions on State, local, and Tribal 
governments and the private sector. Under section 202 of the UMRA, EPA 
generally must prepare a written statement, including a cost-benefit 
analysis, for proposed and final rules with ``Federal mandates'' that 
may result in expenditures to State, local and Tribal governments, in 
the aggregate, or to the private sector, of $100 million or more in any 
one year. Before promulgating an EPA rule for which a written statement 
is needed, section 205 of the UMRA generally requires EPA to identify 
and consider a reasonable number of regulatory alternatives and adopt 
the least costly, most cost-effective or least burdensome alternative 
that achieves the objectives of the rule. The provisions of section 205 
do not apply when they are inconsistent with applicable law. Moreover, 
section 205 allows EPA to adopt an alternative other than the least 
costly, most cost-effective or least burdensome alternative if the 
Administrator publishes with the final rule an explanation why that 
alternative was not adopted. Before EPA establishes any regulatory 
requirements that may significantly or uniquely affect small 
governments, including Tribal governments, it must have developed under 
section 203 of the UMRA a small government agency plan. The plan must 
provide for notifying potentially affected small governments, enabling 
officials of affected small governments to have meaningful and timely 
input in the development of EPA regulatory proposals with significant 
Federal intergovernmental mandates, and informing, educating, and 
advising small governments on compliance with the regulatory 
requirements.
    EPA has determined that this rule may contain a Federal mandate 
that results in expenditures of $100 million or more for the State, 
Local, and Tribal governments, in the aggregate in the private sector 
in any one year. While the annualized costs fall below the $100 million 
threshold, the costs in some future years may be above the $100 million 
mark as public drinking water systems make capital investments and 
finance these through bonds, loans, and other means. EPA's year by year 
cost tables do not reflect that investments through bonds, loans, and 
other means spread out these costs over many years. The cost analysis 
in general does not consider that some systems may be eligible for 
financial assistance such as low-interest loans and grants through such 
programs as the Drinking Water State Revolving Fund.
    As noted earlier, today's final rule is promulgated pursuant to 
section 1412 (b)(1)(A) of the Safe Drinking Water Act (SDWA), as 
amended in 1996, which directs EPA to promulgate a national primary 
drinking water regulation for a contaminant if EPA determines that the 
contaminant may have an adverse effect on the health of persons, occurs 
in PWSs with a frequency and at levels of public health concern, and 
regulation presents a meaningful opportunity for health risk reduction.

[[Page 469]]

    Section VI of this preamble discusses the cost and benefits 
associated with the Stage 2 DBPR. Details are presented in the Economic 
Analysis (USEPA 2005a).

     Table VII.D-1--Public and Private Costs for the Stage 2 DBPR (Annualized at 3 and 7 Percent, $Millions)
----------------------------------------------------------------------------------------------------------------
                                                                              Percent of 3%      Percent of 7%
                                       3% discount rate   7% discount rate  grand total costs  grand total costs
                                                                                 (percent)          (percent)
----------------------------------------------------------------------------------------------------------------
Surface Water Systems Costs.........              $41.4              $41.2                 53                 54
Ground Water Systems Costs..........               20.3               19.2                 26                 25
State Costs.........................                1.7                1.7                  2                  2
Tribal Costs........................                0.4                0.4                  1                  0
    Total Public....................               63.8               62.5                 81                 81
Surface Water Systems Costs.........                6.4                6.3                  8                  8
Ground Water Systems Costs..........                8.5                8.0                 11                 10
    Total Private...................               15.0               14.3                 19                 19
        Grand total.................               78.8               76.8                100               100
----------------------------------------------------------------------------------------------------------------
Note: Detail may not add due to independent rounding. Estimates are discounted to 2003 and given in 2003
  dollars.
 
 Source: Exhibits 3.2 and 7.5, USEPA 2005a.

    To meet the UMRA requirement in section 202, EPA analyzed future 
compliance costs and possible disproportionate budgetary effects. The 
Agency believes that the cost estimates and regulatory alternatives 
indicated earlier and discussed in more detail in section VI of this 
preamble, accurately characterize future compliance costs of today's 
rule.
    In analyzing disproportionate impacts, EPA considered the impact on 
(1) different regions of the United States, (2) State, local, and 
Tribal governments, (3) urban, rural and other types of communities, 
and (4) any segment of the private sector. This analysis is presented 
in Chapter 7of the Economic Analysis (USEPA 2005a). EPA analyzed four 
regulatory alternatives and selected the least costly of these in 
accordance with UMRA Section 205.
    EPA has determined that the Stage 2 DBPR contains no regulatory 
requirements that might significantly or uniquely affect small 
governments. The Stage 2 DBPR affects all size systems. As described in 
section VII.C, EPA has certified that today's rule will not have a 
significant economic impact on a substantial number of small entities. 
Average annual expenditures for small CWSs to comply with the Stage 2 
DBPR range from $27.7 to $26.1 million at a 3 and 7 percent discount 
rate, respectively.
    Consistent with the intergovernmental consultation provisions of 
section 204 of the UMRA and Executive Order 12875, ``Enhancing the 
Intergovernmental Partnership,'' EPA has already initiated 
consultations with the governmental entities affected by this rule. The 
consultations are described in the proposed rule (68 FR 49654, August 
18, 2003).

E. Executive Order 13132: Federalism

    Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August 
10, 1999), requires EPA to develop an accountable process to ensure 
``meaningful and timely input by State and local officials in the 
development of regulatory policies that have federalism implications.'' 
``Policies that have federalism implications'' is defined in the 
Executive Order to include regulations that have ``substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government.''
    This final rule does not have federalism implications. It will not 
have substantial direct effects on the States, on the relationship 
between national government and the States, or on the distribution of 
power and responsibilities among various levels of government, as 
specified in Executive Order 13132. The final rule has one-time costs 
for implementation of approximately $7.8 million. Thus, Executive Order 
13132 does not apply to this rule.
    Although section 6 of Executive Order 13132 does not apply to this 
rule, in the spirit of Executive Order 13132, and consistent with EPA 
policy to promote communications between EPA and State and local 
governments, EPA nonetheless specifically solicited comment on the 
proposed rule from State and local officials and did consult with State 
and local officials in developing this rule. A description of that 
consultation can be found in the preamble to the proposed rule, 68 FR 
49548, (August 18, 2003).

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    Executive Order 13175, entitled ``Consultation and Coordination 
with Indian Tribal Governments'' (65 FR 67249, November 9, 2000), 
requires EPA to develop ``an accountable process to ensure meaningful 
and timely input by tribal officials in the development of regulatory 
policies that have tribal implications.'' Under Executive Order 13175, 
EPA may not issue a regulation that has Tribal implications, that 
imposes substantial direct compliance costs, and that is not required 
by statute, unless the Federal government provides the funds necessary 
to pay the direct compliance costs incurred by Tribal governments, or 
EPA consults with Tribal officials early in the process of developing 
the proposed regulation and develops a Tribal summary impact statement.
    EPA has concluded that this final rule may have Tribal 
implications, because it may impose substantial direct compliance costs 
on Tribal governments, and the Federal government will not provide the 
funds necessary to pay those costs.
    Accordingly, EPA provides the following Tribal summary impact 
statement as required by section 5(b). EPA provides further detail on 
Tribal impact in the Economic Analysis (USEPA 2005a). Total Tribal 
costs are estimated to be approximately $391,773 per year (at a 3 
percent discount rate) and this cost is distributed across 755 Tribal 
systems. The cost for individual systems depend on system size and 
source water type. Of the 755 Tribes that may be affected in some form 
by the Stage 2 DBPR, 654 use ground water as a source and 101 systems 
use surface water or GWUDI. Since the majority of Tribal systems are 
ground water systems

[[Page 470]]

serving fewer than 500 people, approximately 15.6 percent of all Tribal 
systems will have to conduct an IDSE. As a result, the Stage 2 DBPR is 
most likely to have an impact on Tribes using surface water or GWUDI 
serving more than 500 people.
    EPA consulted with Tribal officials early in the process of 
developing this regulation to permit them to have meaningful and timely 
input into its development. Moreover, in the spirit of Executive Order 
13175, and consistent with EPA policy to promote communications between 
EPA and Tribal governments, EPA specifically solicited comment on the 
proposed rule from Tribal officials.
    As required by section 7(a), EPA's Tribal Consultation Official has 
certified that the requirements of the Executive Order has been met in 
a meaningful and timely manner. A copy of this certification has been 
included in the docket for this rule.

G. Executive order 13045: Protection of Children From Environmental 
Health Risks and Safety Risks

    Executive Order 13045: ``Protection of Children from Environmental 
Health Risks and Safety Risks'' (62 FR 19885, April 23, 1997) applies 
to any rule that: (1) is determined to be ``economically significant'' 
as defined under 12866, and; (2) concerns an environmental health or 
safety risk that EPA has reason to believe may have a disproportionate 
effect on children. If the regulatory action meets both criteria, the 
Agency must evaluate the environmental health or safety effects of the 
planned rule on children, and explain why the planned regulation is 
preferable to other potentially effective and reasonably feasible 
alternatives considered by the Agency.
    While this final rule is not subject to the Executive Order because 
it is not economically significant as defined in Executive Order 12866, 
EPA nonetheless has reason to believe that the environmental health or 
safety risk (i.e., the risk associated with DBPs) addressed by this 
action may have a disproportionate effect on children. EPA believes 
that the Stage 2 DBPR will result in greater risk reduction for 
children than for the general population. The results of the 
assessments are contained in Section VI.I of this preamble and in the 
Economic Analysis (USEPA 2005a). A copy of all documents has been 
placed in the public docket for this action.

H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use

    This rule is not a ``significant energy action'' as defined in 
Executive Order 13211, ``Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use'' (66 FR 
28355, May 22, 2001) because it is not likely to have a significant 
adverse effect on the supply, distribution, or use of energy. This 
determination is based on the following analysis.
    The first consideration is whether the Stage 2 DBPR would adversely 
affect the supply of energy. The Stage 2 DBPR does not regulate power 
generation, either directly or indirectly. The public and private 
utilities that the Stage 2 DBPR regulates do not, as a rule, generate 
power. Further, the cost increases borne by customers of water 
utilities as a result of the Stage 2 DBPR are a low percentage of the 
total cost of water, except for a very few small systems that might 
install advanced technologies that must spread that cost over a narrow 
customer base. Therefore, the customers that are power generation 
utilities are unlikely to face any significant effects as a result of 
the Stage 2 DBPR. In sum, the Stage 2 DBPR does not regulate the supply 
of energy, does not generally regulate the utilities that supply 
energy, and is unlikely significantly to affect the customer base of 
energy suppliers. Thus, the Stage 2 DBPR would not translate into 
adverse effects on the supply of energy.
    The second consideration is whether the Stage 2 DBPR would 
adversely affect the distribution of energy. The Stage 2 DBPR does not 
regulate any aspect of energy distribution. The utilities that are 
regulated by the Stage 2 DBPR already have electrical service. As 
derived later in this section, the final rule is projected to increase 
peak electricity demand at water utilities by only 0.009 percent. 
Therefore, EPA estimates that the existing connections are adequate and 
that the Stage 2 DBPR has no discernable adverse effect on energy 
distribution.
    The third consideration is whether the Stage 2 DBPR would adversely 
affect the use of energy. Because some drinking water utilities are 
expected to add treatment technologies that use electrical power, this 
potential impact is evaluated in more detail. The analyses that 
underlay the estimation of costs for the Stage 2 DBPR are national in 
scope and do not identify specific plants or utilities that may install 
treatment in response to the rule. As a result, no analysis of the 
effect on specific energy suppliers is possible with the available 
data. The approach used to estimate the impact of energy use, 
therefore, focuses on national-level impacts. The analysis estimates 
the additional energy use due to the Stage 2 DBPR and compares that 
analysis to the national levels of power generation in terms of average 
and peak loads.
    The first step in the analysis is to estimate the energy used by 
the technologies expected to be installed as a result of the Stage 2 
DBPR. Energy use is not directly stated in Technologies and Costs for 
the Final Long Term 2 Enhanced Surface Water Treatment Rule and Final 
Stage 2 Disinfectants and Disinfection Byproducts Rule (USEPA 2005g), 
but the annual cost of energy for each technology addition or upgrade 
necessitated by the Stage 2 DBPR is provided. An estimate of plant-
level energy use is derived by dividing the total energy cost per plant 
for a range of flows by an average national cost of electricity of 
$0.076/ kilowatt hours per year (kWh/yr) (USDOE 2004a). These 
calculations are shown in detail in the Economic Analysis (USEPA 
2005a). The energy use per plant for each flow range and technology is 
then multiplied by the number of plants predicted to install each 
technology in a given flow range. The energy requirements for each flow 
range are then added to produce a national total. No electricity use is 
subtracted to account for the technologies that may be replaced by new 
technologies, resulting in a conservative estimate of the increase in 
energy use. The incremental national annual energy usage is 0.12 
million megawatt-hours (MWh).
    According to the U.S. Department of Energy's Information 
Administration, electricity producers generated 3,848 million MWh of 
electricity in 2003 (USDOE 2004b). Therefore, even using the highest 
assumed energy use for the Stage 2 DBPR, the rule when fully 
implemented would result in only a 0.003 percent increase in annual 
average energy use.
    In addition to average energy use, the impact at times of peak 
power demand is important. To examine whether increased energy usage 
might significantly affect the capacity margins of energy suppliers, 
their peak season generating capacity reserve was compared to an 
estimate of peak incremental power demand by water utilities.
    Both energy use and water use peak in the summer months, so the 
most significant effects on supply would be seen then. In the summer of 
2003, U.S. generation capacity exceeded consumption by 15 percent, or

[[Page 471]]

approximately 160,000 MW (USDOE 2004b). Assuming around-the-clock 
operation of water treatment plants, the total energy requirement can 
be divided by 8,760 hours per year to obtain an average power demand of 
13.28 MW. A more detailed derivation of this value is shown in the 
Economic Analysis (USEPA 2005a). Assuming that power demand is 
proportional to water flow through the plant and that peak flow can be 
as high as twice the average daily flow during the summer months, about 
26.55 MW could be needed for treatment technologies installed to comply 
with the Stage 2 DBPR. This is only 0.017 percent of the capacity 
margin available at peak use.
    Although EPA recognizes that not all areas have a 15 percent 
capacity margin and that this margin varies across regions and through 
time, this analysis reflects the effect of the rule on national energy 
supply, distribution, and use. While certain areas, notably California, 
have experienced shortfalls in generating capacity in the recent past, 
a peak incremental power requirement of 26.55 MW nationwide is not 
likely to significantly change the energy supply, distribution, or use 
in any given area. Considering this analysis, EPA has concluded that 
Stage 2 DBPR will not have any significant effect on the use of energy, 
based on annual average use and on conditions of peak power demand.

I. National Technology Transfer and Advancement Act

    As noted in the proposed rule, Section 12(d) of the National 
Technology Transfer and Advancement Act of 1995 (``NTTAA''), Public Law 
104-113, section 12(d) (15 U.S.C. 272 note) directs EPA to use 
voluntary consensus standards in its regulatory activities unless to do 
so would be inconsistent with applicable law or otherwise impractical. 
Voluntary consensus standards are technical standards (e.g., materials 
specifications, test methods, sampling procedures, and business 
practices) that are developed or adopted by voluntary consensus 
standard bodies. The NTTAA directs EPA to provide Congress, through 
OMB, explanations when the Agency decides not to use available and 
applicable voluntary consensus standards.
    This rulemaking involves technical standards. EPA has decided to 
use two voluntary consensus methods for HAA5 (Standard Method 6251 B, 
1998 in the 20th Edition of Standard Methods for the Examination of 
Water and Wastewater and Standard Method 6251 B-94, 1994 available at 
http://www.standardmethods.org). In addition to these two consensus 
methods, EPA is also approving EPA Method 552.3 for HAA5, which also 
can be used to measure three unregulated HAAs that are not included in 
the consensus methods. The unregulated HAAs are included in the EPA 
method because some water systems monitor for them in order to better 
understand their treatment processes and provide greater public health 
protection. EPA is approving two voluntary consensus standards for 
daily monitoring for chlorite (Standard Method 4500-ClO2 E, 
1998, in the 20th Edition of Standard Methods for the Examination of 
Water and Wastewater and Standard Method 4500-ClO2 E-00, 
2000, available at http://www.standardmethods.org). EPA Method 327.0, 
Revision 1.1 is also being approved for daily monitoring for both 
chlorite and chlorine dioxide in order to provide an alternative to the 
titration procedure that is required in the Standard Methods. EPA is 
approving a method from American Society for Testing and Materials 
International for bromate, chlorite and bromide analyses (ASTM D 6581-
00, 2000, ASTM International. Annual Book of ASTM Standards, Volume 
11.01, American Society for Testing and Materials International, 2001 
or any year containing the cited version of the method may be used). 
EPA is also approving three EPA methods (EPA Methods 317.0 Revision 
2.0, 321.8, and 326.0) that provide greater sensitivity and selectivity 
for bromate than the ASTM consensus standard. These EPA methods are 
required in order to provide better process control for water systems 
using ozone in the treatment process and to allow for a reduced 
monitoring option. EPA Methods 317.0 Revision 2.0 and 326.0 can also be 
used to determine chlorite and bromide. Today's action approves eight 
voluntary consensus standards for determining free, combined, and total 
chlorine (SM 4500-Cl D, SM 4500-Cl F, and 4500-Cl G, 1998, in the 20th 
Edition of Standard Methods for the Examination of Water and Wastewater 
and SM 4500-Cl D-00, SM 4500-Cl F-00, and 4500-Cl G-00, 2000 available 
at http://www.standardmethods.org and ASTM D 1253-86(96), 1996, ASTM 
International, Annual Book of ASTM Standards, Volume 11.01, American 
Society for Testing and Materials International, 1996 or any year 
containing the cited version of the method may be used and ASTM D 1253-
03, 2003, ASTM International, Annual Book of ASTM Standards, Volume 
11.01, American Society for Testing and Materials International, 2004 
or any year containing the cited version of the method may be used). 
EPA is approving four standards for determining total chlorine (SM 
4500-Cl E and SM 4500-Cl I, 1998, in the 20th Edition of Standard 
Methods for the Examination of Water and Wastewater and SM 4500-Cl E-00 
and SM 4500-Cl I-00, 2000 available at http://www.standardmethods.org). 
Two standards for determining free chlorine are approved in today's 
rule (SM 4500-Cl H, 1998, in the 20th Edition of Standard Methods for 
the Examination of Water and Wastewater and SM 4500-Cl H-00, 2000 
available at http://www.standardmethods.org). Today's action approves 
three voluntary consensus standards for measuring chlorine dioxide 
(4500-ClO2 D and 4500-ClO2 E, 1998, in the 20th 
Edition of Standard Methods for the Examination of Water and Wastewater 
and 4500-ClO2 E-00, 2000 available at http://
www.standardmethods.org). EPA is approving six standards for 
determining TOC and DOC (SM 5310 B, SM 5310 C, and SM 5310 D, 1998, in 
the 20th Edition of Standard Methods for the Examination of Water and 
Wastewater and SM 5310 B-00, SM 5310 C-00, and SM 5310 D-00, 2000 
available at http://www.standardmethods.org). Two standards for 
determining UV254 are approved in today's rule (SM 5910 B, 
1998, in the 20th Edition of Standard Methods for the Examination of 
Water and Wastewater and SM 5910 B-00, 2000 available at http://
www.standardmethods.org). EPA is also approving EPA Method 415.3 
Revision 1.1 for the determination of TOC and SUVA (DOC and 
UV254). This EPA method contains method performance data 
that are not available in the consensus standards.
    Copies of the ASTM standards may be obtained from the American 
Society for Testing and Materials International, 100 Barr Harbor Drive, 
West Conshohocken, PA 19428-2959. The Standard Methods may be obtained 
from the American Public Health Association, 1015 Fifteenth Street, 
NW., Washington, DC 20005.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations or Low-Income Populations

    Executive Order 12898 establishes a Federal policy for 
incorporating environmental justice into Federal agency missions by 
directing agencies to identify and address disproportionately high and 
adverse human health or environmental effects of its programs, 
policies, and activities on minority and low-income populations. EPA 
has

[[Page 472]]

considered environmental justice related issues concerning the 
potential impacts of this action and consulted with minority and low-
income stakeholders. A description of this consultation can be found in 
the proposed rule (USEPA 2003a).

K. Consultations With the Science Advisory Board, National Drinking 
Water Advisory Council, and the Secretary of Health and Human Services

    In accordance with Section 1412(d) and (e) of the SDWA, the Agency 
consulted with the Science Advisory Board, the National Drinking Water 
Advisory Council (NDWAC), and the Secretary of Health and Human 
Services on today's rule.
    EPA met with the SAB to discuss the Stage 2 DBPR on June 13, 2001 
(Washington, DC), September 25-26, 2001 (teleconference), and December 
10-12, 2001 (Los Angeles, CA). Written comments from the December 2001 
meeting of the SAB addressing the occurrence analysis and risk 
assessment were generally supportive. SAB comments are discussed in 
greater detail within the proposal.
    EPA met with the NDWAC on November 8, 2001, in Washington, DC to 
discuss the Stage 2 DBPR proposal. The Advisory Committee generally 
supported the need for the Stage 2 DBPR based on health and occurrence 
data, but also stressed the importance of providing flexibility to the 
systems implementing the rule. The results of these discussions are 
included in the docket for the proposed rule.

L. Plain Language

    Executive Order 12866 requires each agency to write its rules in 
plain language. Readable regulations help the public find requirements 
quickly and understand them easily. They increase compliance, 
strengthen enforcement, and decrease mistakes, frustration, phone 
calls, appeals, and distrust of government. EPA made every effort to 
write this preamble to the final rule in as clear, concise, and 
unambiguous manner as possible.

M. Analysis of the Likely Effect of Compliance With the Stage 2 DBPR on 
the Technical, Managerial, and Financial Capacity of Public Water 
Systems

    Section 1420(d)(3) of SDWA, as amended, requires that, in 
promulgating a National Primary Drinking Water Regulation (NPDWR), the 
Administrator shall include an analysis of the likely effect of 
compliance with the regulation on the technical, managerial, and 
financial (TMF) capacity of PWSs. This analysis is described in more 
detail and can be found in the Economic Analysis (USEPA 2005a). 
Analyses reflect only the impact of new or revised requirements, as 
established by the LT2ESWTR; the impacts of previously established 
requirements on system capacity are not considered.
    EPA has defined overall water system capacity as the ability to 
plan for, achieve, and maintain compliance with applicable drinking 
water standards. Capacity encompasses three components: technical, 
managerial, and financial. Technical capacity is the physical and 
operational ability of a water system to meet SDWA requirements. This 
refers to the physical infrastructure of the water system, including 
the adequacy of source water and the adequacy of treatment, storage, 
and distribution infrastructure. It also refers to the ability of 
system personnel to adequately operate and maintain the system and to 
otherwise implement requisite technical knowledge. Managerial capacity 
is the ability of a water system to conduct its affairs to achieve and 
maintain compliance with SDWA requirements. Managerial capacity refers 
to the system's institutional and administrative capabilities. 
Financial capacity is a water system's ability to acquire and manage 
sufficient financial resources to allow the system to achieve and 
maintain compliance with SDWA requirements.
    EPA estimated the impact of the Stage 2 DBPR on small and large 
system capacity as a result of the measures that systems are expected 
to adopt to meet the requirements of the rule (e.g., selecting 
monitoring sites for the IDSE, installing/upgrading treatment, operator 
training, communication with regulators and the service community, 
etc.). The Stage 2 DBPR may have a substantial impact on the capacity 
of the 1,743 plants in small systems and 518 plants in large systems 
that must make changes to their treatment process to meet the Stage 2 
DBPR requirements. However, while the impact to these systems is 
potentially significant, only 3.8 percent of all plants regulated under 
the Stage 2 DBPR (2,261 of 60,220) will be affected by this 
requirement. Since individual systems may employ more than one plant, 
it is likely that fewer than 1,620 systems (3.4 percent of 48,293 
systems) will be affected by this requirement. The new IDSE and 
monitoring requirements are expected to have a small impact on the 
technical and managerial capacity of small systems, a moderate impact 
on the financial capacity of some small systems, and a much smaller 
impact on large systems. The capacity of systems that must conduct an 
operational evaluation will only be impacted in a minor way, while 
those systems that must only familiarize themselves with the rule (the 
large majority of systems) will not face any capacity impact as a 
result of the Stage 2 DBPR.

N. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. EPA will submit a report containing this rule and other 
required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. A Major rule cannot 
take effect until 60 days after it is published in the Federal 
Register. This action is a ``major rule'' as defined by 5 U.S.C. 
804(2). This rule will be effective March 6, 2006.

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Kogenvinas, M. 2003. Meta-analysis of Studies on Individual 
Consumption of Chlorinated Drinking Water and Bladder Cancer. 
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Villanueva, C.M., K.P. Cantor, S. Cordier, J.J.K. Jaakkola, W.D. 
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List of Subjects

40 CFR Part 9

    Reporting and recordkeeping requirements.

40 CFR Part 141

    Environmental protection, Chemicals, Indians-lands, Incorporation 
by reference, Intergovernmental relations, Radiation protection, 
Reporting and recordkeeping requirements, Water supply.

40 CFR Part 142

    Environmental protection, Administrative practice and procedure, 
Chemicals, Indians-lands, Radiation protection, Reporting and 
recordkeeping requirements, Water supply.

    Dated: December 15, 2005.
Stephen L. Johnson,
Administrator.

0
For the reasons set forth in the preamble, title 40 chapter I of the 
Code of Federal Regulations is amended as follows:

PART 9--OMB APPROVALS UNDER THE PAPERWORK REDUCTION ACT

0
1. The authority citation for part 9 continues to read as follows:

    Authority: 7 U.S.C. 135 et seq., 136-136y; 15 U.S.C. 2001, 2003, 
2005, 2006, 2601-2671; 21 U.S.C. 331j, 346a, 348; 31 U.S.C. 9701; 33 
U.S.C. 1251 et seq., 1311, 1313d, 1314, 1318, 1321, 1326, 1330, 
1342, 1344, 1345 (d) and (e), 1361; Executive Order 11735, 38 FR 
21243, 3 CFR, 1971-1975 Comp. p. 973; 42 U.S.C. 241, 242b, 243, 246, 
300f, 300g, 300g-1, 300g-2, 300g-3, 300g-4, 300g-5, 300g-6, 300j-1, 
300j-2, 300j-3, 300j-4, 300j-9, 1857 et seq., 6901-6992k, 7401-
7671q, 7542, 9601-9657, 11023, 11048.


0
2. In Sec.  9.1 the table is amended as follows:
0
a. Under the heading ``National Primary Drinking Water Regulations 
Implementation'' by adding entries in numerical order for ``Sec.  
141.600-141.605, 141.620-141.626, 141.629''.
0
b. Under the heading ``National Primary Drinking Water Regulations 
Implementation'' by removing entries ``Sec.  142.14(a),142.14(a)-
(d)(3)'' and adding entries in numerical order for ``142.14(a) (1)-(7), 
142.14(a)(8), 142.14(b)-(d) and 142.16(m)'' as follows:


Sec.  9.1  OMB approvals under the Paperwork Reduction Act.

* * * * *

------------------------------------------------------------------------
                                                            OMB control
                     40 CFR citation                            No.
------------------------------------------------------------------------
 
                                * * * * *
---------------------------------------------------------
               National Primary Drinking Water Regulations
------------------------------------------------------------------------
 
                                * * * * *
141.600-141.605.........................................       2040-0265
141.620-141.626.........................................       2040-0265
141.629.................................................       2040-0265
---------------------------------------------------------
       National Primary Drinking Water Regulations Implementation
------------------------------------------------------------------------
 
                                * * * * *
142.14(a)(1)-(7)........................................       2040-0265
142.14(a)(8)............................................       2040-0265
142.14(b)-(d)...........................................       2040-0090
 
                                * * * * *
142.16(m)...............................................       2040-0265
------------------------------------------------------------------------

* * * * *

PART 141--NATIONAL PRIMARY DRINKING WATER REGULATIONS

0
3. The authority citation for part 141 continues to read as follows:

    Authority: 42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-
5, 300g-6, 300j-4, 300j-9, and 300j-11.


0
4. Section 141.2 is amended by adding, in alphabetical order, 
definitions for ``Combined distribution system'', ``Consecutive 
system'', ``Dual sample sets'', ``Finished water'', ``GAC20'', 
``Locational running annual average'', and ``Wholesale system'' and 
revising the definition of ``GAC10'' to read as follows:


Sec.  141.2  Definitions.

* * * * *
    Combined distribution system is the interconnected distribution 
system consisting of the distribution systems of wholesale systems and 
of the consecutive systems that receive finished water.
* * * * *
    Consecutive system is a public water system that receives some or 
all of its finished water from one or more wholesale systems. Delivery 
may be through a direct connection or through the distribution system 
of one or more consecutive systems.
* * * * *
    Dual sample set is a set of two samples collected at the same time 
and same location, with one sample analyzed for TTHM and the other

[[Page 478]]

sample analyzed for HAA5. Dual sample sets are collected for the 
purposes of conducting an IDSE under subpart U of this part and 
determining compliance with the TTHM and HAA5 MCLs under subpart V of 
this part.
* * * * *
    Finished water is water that is introduced into the distribution 
system of a public water system and is intended for distribution and 
consumption without further treatment, except as treatment necessary to 
maintain water quality in the distribution system (e.g., booster 
disinfection, addition of corrosion control chemicals).
* * * * *
    GAC10 means granular activated carbon filter beds with an empty-bed 
contact time of 10 minutes based on average daily flow and a carbon 
reactivation frequency of every 180 days, except that the reactivation 
frequency for GAC10 used as a best available technology for compliance 
with subpart V MCLs under Sec.  141.64(b)(2) shall be 120 days.
    GAC20 means granular activated carbon filter beds with an empty-bed 
contact time of 20 minutes based on average daily flow and a carbon 
reactivation frequency of every 240 days.
* * * * *
    Locational running annual average (LRAA) is the average of sample 
analytical results for samples taken at a particular monitoring 
location during the previous four calendar quarters.
* * * * *
    Wholesale system is a public water system that treats source water 
as necessary to produce finished water and then delivers some or all of 
that finished water to another public water system. Delivery may be 
through a direct connection or through the distribution system of one 
or more consecutive systems.


Sec.  141.12  [Removed]

0
5. Section 141.12 is removed and reserved.


Sec.  141.30  [Removed]

0
6. Section 141.30 is removed.


Sec.  141.32  [Removed]

0
7. Section 141.32 is removed and reserved.

0
8. Section 141.33 is amended by revising the first sentence of 
paragraph (a) introductory text and adding paragraph (f) to read as 
follows:


Sec.  141.33  Record maintenance.

* * * * *
    (a) Records of microbiological analyses and turbidity analyses made 
pursuant to this part shall be kept for not less than 5 years. * * *
* * * * *
    (f) Copies of monitoring plans developed pursuant to this part 
shall be kept for the same period of time as the records of analyses 
taken under the plan are required to be kept under paragraph (a) of 
this section, except as specified elsewhere in this part.

0
9. Section 141.53 is amended by revising the table to read as follows:


Sec.  141.53  Maximum contaminant level goals for disinfection 
byproducts.

* * * * *

------------------------------------------------------------------------
          Disinfection byproduct                     MCLG (mg/L)
------------------------------------------------------------------------
Bromodichloromethane......................  zero
Bromoform.................................  zero
Bromate...................................  zero
Chlorite..................................  0.8
Chloroform................................  0.07
Dibromochloromethane......................  0.06
Dichloroacetic acid.......................  zero
Monochloroacetic acid.....................  0.07
Trichloroacetic acid......................  0.02
------------------------------------------------------------------------


0
10. Section 141.64 is revised to read as follows:


Sec.  141.64  Maximum contaminant levels for disinfection byproducts.

    (a) Bromate and chlorite. The maximum contaminant levels (MCLs) for 
bromate and chlorite are as follows:

------------------------------------------------------------------------
                   Disinfection byproduct                     MCL (mg/L)
------------------------------------------------------------------------
Bromate....................................................        0.010
Chlorite...................................................        1.0
------------------------------------------------------------------------

    (1) Compliance dates for CWSs and NTNCWSs. Subpart H systems 
serving 10,000 or more persons must comply with this paragraph (a) 
beginning January 1, 2002. Subpart H systems serving fewer than 10,000 
persons and systems using only ground water not under the direct 
influence of surface water must comply with this paragraph (a) 
beginning January 1, 2004.
    (2) The Administrator, pursuant to section 1412 of the Act, hereby 
identifies the following as the best technology, treatment techniques, 
or other means available for achieving compliance with the maximum 
contaminant levels for bromate and chlorite identified in this 
paragraph (a):

------------------------------------------------------------------------
         Disinfection byproduct             Best available technology
------------------------------------------------------------------------
Bromate................................  Control of ozone treatment
                                          process to reduce production
                                          of bromate
Chlorite...............................  Control of treatment processes
                                          to reduce disinfectant demand
                                          and control of disinfection
                                          treatment processes to reduce
                                          disinfectant levels
------------------------------------------------------------------------

    (b) TTHM and HAA5. (1) Subpart L--RAA compliance. (i) Compliance 
dates. Subpart H systems serving 10,000 or more persons must comply 
with this paragraph (b)(1) beginning January 1, 2002. Subpart H systems 
serving fewer than 10,000 persons and systems using only ground water 
not under the direct influence of surface water must comply with this 
paragraph (b)(1) beginning January 1, 2004. All systems must comply 
with these MCLs until the date specified for subpart V compliance in 
Sec.  141.620(c).

------------------------------------------------------------------------
                   Disinfection byproduct                     MCL (mg/L)
------------------------------------------------------------------------
Total trihalomethanes (TTHM)...............................        0.080
Haloacetic acids (five) (HAA5).............................        0.060
------------------------------------------------------------------------

    (ii) The Administrator, pursuant to section 1412 of the Act, hereby 
identifies the following as the best technology, treatment techniques, 
or other means available for achieving compliance with the maximum 
contaminant levels for TTHM and HAA5 identified in this paragraph 
(b)(1):

------------------------------------------------------------------------
          Disinfection byproduct              Best available technology
------------------------------------------------------------------------
Total trihalomethanes (TTHM) and            Enhanced coagulation or
 Haloacetic acids (five) (HAA5).             enhanced softening or
                                             GAC10, with chlorine as the
                                             primary and residual
                                             disinfectant
------------------------------------------------------------------------

    (2) Subpart V--LRAA compliance. (i) Compliance dates. The subpart V 
MCLs for TTHM and HAA5 must be complied with as a locational running 
annual average at each monitoring location beginning the date specified 
for subpart V compliance in Sec.  141.620(c).

------------------------------------------------------------------------
                   Disinfection byproduct                     MCL (mg/L)
------------------------------------------------------------------------
Total trihalomethanes (TTHM)...............................        0.080
Haloacetic acids (five) (HAA5).............................        0.060
------------------------------------------------------------------------

    (ii) The Administrator, pursuant to section 1412 of the Act, hereby 
identifies the following as the best technology, treatment techniques, 
or other means available for achieving compliance with the maximum 
contaminant levels for TTHM and HAA5 identified in this paragraph 
(b)(2)

[[Page 479]]

for all systems that disinfect their source water:

------------------------------------------------------------------------
         Disinfection byproduct             Best available technology
------------------------------------------------------------------------
Total trihalomethanes (TTHM) and         Enhanced coagulation or
 Haloacetic acids (five) (HAA5).          enhanced softening, plus
                                          GAC10; or nanofiltration with
                                          a molecular weight cutoff
                                          <=1000 Daltons; or GAC20
------------------------------------------------------------------------

    (iii) The Administrator, pursuant to section 1412 of the Act, 
hereby identifies the following as the best technology, treatment 
techniques, or other means available for achieving compliance with the 
maximum contaminant levels for TTHM and HAA5 identified in this 
paragraph (b)(2) for consecutive systems and applies only to the 
disinfected water that consecutive systems buy or otherwise receive:

------------------------------------------------------------------------
         Disinfection byproduct             Best available technology
------------------------------------------------------------------------
Total trihalomethanes (TTHM) and         Systems serving >=10,000:
 Haloacetic acids (five) (HAA5).          Improved distribution system
                                          and storage tank management to
                                          reduce residence time, plus
                                          the use of chloramines for
                                          disinfectant residual
                                          maintenance
                                         Systems serving <10,000:
                                          Improved distribution system
                                          and storage tank management to
                                          reduce residence time
------------------------------------------------------------------------


0
11. Section 141.131 is amended as follows:
0
a. By revising paragraph (a),
0
b. By revising paragraphs (b)(1) and (b)(2),
0
c. By revising the table in paragraph (c)(1),
0
d. By revising paragraphs (d)(2), (d)(3), (d)(4)(i), and (d)(4)(ii),
0
e. By adding paragraph (d)(6).


Sec.  141.131  Analytical requirements.

    (a) General. (1) Systems must use only the analytical methods 
specified in this section, or their equivalent as approved by EPA, to 
demonstrate compliance with the requirements of this subpart and with 
the requirements of subparts U and V of this part. These methods are 
effective for compliance monitoring February 16, 1999, unless a 
different effective date is specified in this section or by the State.
    (2) The following documents are incorporated by reference. The 
Director of the Federal Register approves this incorporation by 
reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies 
may be inspected at EPA's Drinking Water Docket, 1301 Constitution 
Avenue, NW., EPA West, Room B102, Washington, DC 20460, or at the 
National Archives and Records Administration (NARA). For information on 
the availability of this material at NARA, call 202-741-6030, or go to: 
http://www.archives.gov/federal_register/code_of_federal_
regulations/ibr_locations.html. EPA Method 552.1 is in Methods for the 
Determination of Organic Compounds in Drinking Water-Supplement II, 
USEPA, August 1992, EPA/600/R-92/129 (available through National 
Information Technical Service (NTIS), PB92-207703). EPA Methods 502.2, 
524.2, 551.1, and 552.2 are in Methods for the Determination of Organic 
Compounds in Drinking Water-Supplement III, USEPA, August 1995, EPA/
600/R-95/131 (available through NTIS, PB95-261616). EPA Method 300.0 is 
in Methods for the Determination of Inorganic Substances in 
Environmental Samples, USEPA, August 1993, EPA/600/R-93/100 (available 
through NTIS, PB94-121811). EPA Methods 300.1 and 321.8 are in Methods 
for the Determination of Organic and Inorganic Compounds in Drinking 
Water, Volume 1, USEPA, August 2000, EPA 815-R-00-014 (available 
through NTIS, PB2000-106981). EPA Method 317.0, Revision 2.0, 
``Determination of Inorganic Oxyhalide Disinfection By-Products in 
Drinking Water Using Ion Chromatography with the Addition of a 
Postcolumn Reagent for Trace Bromate Analysis,'' USEPA, July 2001, EPA 
815-B-01-001, EPA Method 326.0, Revision 1.0, ``Determination of 
Inorganic Oxyhalide Disinfection By-Products in Drinking Water Using 
Ion Chromatography Incorporating the Addition of a Suppressor Acidified 
Postcolumn Reagent for Trace Bromate Analysis,'' USEPA, June 2002, EPA 
815-R-03-007, EPA Method 327.0, Revision 1.1, ``Determination of 
Chlorine Dioxide and Chlorite Ion in Drinking Water Using Lissamine 
Green B and Horseradish Peroxidase with Detection by Visible 
Spectrophotometry,'' USEPA, May 2005, EPA 815-R-05-008 and EPA Method 
552.3, Revision 1.0, ``Determination of Haloacetic Acids and Dalapon in 
Drinking Water by Liquid-liquid Microextraction, Derivatization, and 
Gas Chromatography with Electron Capture Detection,'' USEPA, July 2003, 
EPA-815-B-03-002 can be accessed and downloaded directly on-line at 
http://www.epa.gov/safewater/methods/sourcalt.html. EPA Method 415.3, 
Revision 1.1, ``Determination of Total Organic Carbon and Specific UV 
Absorbance at 254 nm in Source Water and Drinking Water,'' USEPA, 
February 2005, EPA/600/R-05/055 can be accessed and downloaded directly 
on-line at www.epa.gov/nerlcwww/ordmeth.htm. Standard Methods 4500-Cl 
D, 4500-Cl E, 4500-Cl F, 4500-Cl G, 4500-Cl H, 4500-Cl I, 4500-
ClO2 D, 4500-ClO2 E, 6251 B, and 5910 B shall be 
followed in accordance with Standard Methods for the Examination of 
Water and Wastewater, 19th or 20th Editions, American Public Health 
Association, 1995 and 1998, respectively. The cited methods published 
in either edition may be used. Standard Methods 5310 B, 5310 C, and 
5310 D shall be followed in accordance with the Supplement to the 19th 
Edition of Standard Methods for the Examination of Water and 
Wastewater, or the Standard Methods for the Examination of Water and 
Wastewater, 20th Edition, American Public Health Association, 1996 and 
1998, respectively. The cited methods published in either edition may 
be used. Copies may be obtained from the American Public Health 
Association, 1015 Fifteenth Street, NW., Washington, DC 20005. Standard 
Methods 4500-Cl D-00, 4500-Cl E-00, 4500-Cl F-00, 4500-Cl G-00, 4500-Cl 
H-00, 4500-Cl I-00, 4500-ClO2 E-00, 6251 B-94, 5310 B-00, 
5310 C-00, 5310 D-00 and 5910 B-00 are available at http://
www.standardmethods.org or at EPA's Water Docket. The year in which 
each method was approved by the Standard Methods Committee is 
designated by the last two digits in the method number. The methods 
listed are the only Online versions that are IBR-approved. ASTM Methods 
D 1253-86 and D 1253-86 (Reapproved 1996) shall be followed in 
accordance with the Annual Book of ASTM Standards, Volume 11.01, 
American Society for Testing and Materials International, 1996 or any 
ASTM edition containing the IBR-approved version of the method may be 
used. ASTM Method D1253-03 shall be followed in accordance with the 
Annual Book of ASTM Standards, Volume 11.01, American Society for 
Testing and Materials International, 2004 or any ASTM edition 
containing the IBR-approved version of the method may be used. ASTM 
Method D 6581-00 shall be followed in accordance with the Annual Book 
of ASTM Standards, Volume 11.01, American Society for Testing and 
Materials International, 2001 or any ASTM edition containing the IBR-
approved version of the method may be used; copies may be obtained from 
the American Society for Testing and

[[Page 480]]

Materials International, 100 Barr Harbor Drive, West Conshohocken, PA 
19428-2959.
    (b) Disinfection byproducts. (1) Systems must measure disinfection 
byproducts by the methods (as modified by the footnotes) listed in the 
following table:

                        Approved Methods for Disinfection Byproduct Compliance Monitoring
----------------------------------------------------------------------------------------------------------------
                                                     Standard method
Contaminant and methodology \1\      EPA method            \2\           SM online \9\        ASTM method \3\
----------------------------------------------------------------------------------------------------------------
TTHM
    P&T/GC/ElCD & PID..........  502.2 \4\........  .................  .................  ......................
    P&T/GC/MS..................  524.2............  .................  .................  ......................
    LLE/GC/ECD.................  551.1............  .................  .................  ......................
HAA5
    LLE (diazomethane)/GC/ECD..  .................  6251 B \5\.......  6251 B-94........  ......................
    SPE (acidic methanol)/GC/    552.1 \5\........  .................  .................  ......................
     ECD.
    LLE (acidic methanol)/GC/    552.2, 552.3.....  .................  .................  ......................
     ECD.
Bromate
    Ion chromatography.........  300.1............  .................  .................  D 6581-00
    Ion chromatography & post    317.0 Rev 2.0      .................  .................  ......................
     column reaction.             \6\, 326.0 \6\.
    IC/ICP-MS..................  321.86 7.........  .................  .................  ......................
Chlorite
    Amperometric titration.....  .................  4500-ClO2 E \8\..  4500-ClO2 E-00     ......................
                                                                        \8\.
    Spectrophotometry..........  327.0 Rev 1.1 \8\  .................  .................  ......................
    Ion chromatography.........  300.0, 300.1,      .................  .................  D 6581-00
                                  317.0 Rev 2.0,
                                  326.0.
----------------------------------------------------------------------------------------------------------------
\1\ P&T = purge and trap; GC = gas chromatography; ElCD = electrolytic conductivity detector; PID =
  photoionization detector; MS = mass spectrometer; LLE = liquid/liquid extraction; ECD = electron capture
  detector; SPE = solid phase extraction; IC = ion chromatography; ICP-MS = inductively coupled plasma/mass
  spectrometer.
\2\ 19th and 20th editions of Standard Methods for the Examination of Water and Wastewater, 1995 and 1998,
  respectively, American Public Health Association; either of these editions may be used.
\3\ Annual Book of ASTM Standards, 2001 or any year containing the cited version of the method, Vol 11.01.
\4\ If TTHMs are the only analytes being measured in the sample, then a PID is not required.
\5\ The samples must be extracted within 14 days of sample collection.
\6\ Ion chromatography & post column reaction or IC/ICP-MS must be used for monitoring of bromate for purposes
  of demonstrating eligibility of reduced monitoring, as prescribed in Sec.   141.132(b)(3)(ii).
\7\ Samples must be preserved at the time of sampling with 50 mg ethylenediamine (EDA)/L of sample and must be
  analyzed within 28 days.
\8\ Amperometric titration or spectrophotometry may be used for routine daily monitoring of chlorite at the
  entrance to the distribution system, as prescribed in Sec.   141.132(b)(2)(i)(A). Ion chromatography must be
  used for routine monthly monitoring of chlorite and additional monitoring of chlorite in the distribution
  system, as prescribed in Sec.   141.132(b)(2)(i)(B) and (b)(2)(ii).
\9\ The Standard Methods Online version that is approved is indicated by the last two digits in the method
  number which is the year of approval by the Standard Method Committee. Standard Methods Online are available
  at http://www.standardmethods.org.

    (2) Analyses under this section for disinfection byproducts must be 
conducted by laboratories that have received certification by EPA or 
the State, except as specified under paragraph (b)(3) of this section. 
To receive certification to conduct analyses for the DBP contaminants 
in Sec. Sec.  141.64, 141.135, and subparts U and V of this part, the 
laboratory must:
    (i) Analyze Performance Evaluation (PE) samples that are acceptable 
to EPA or the State at least once during each consecutive 12 month 
period by each method for which the laboratory desires certification.
    (ii) Until March 31, 2007, in these analyses of PE samples, the 
laboratory must achieve quantitative results within the acceptance 
limit on a minimum of 80% of the analytes included in each PE sample. 
The acceptance limit is defined as the 95% confidence interval 
calculated around the mean of the PE study between a maximum and 
minimum acceptance limit of +/-50% and +/-15% of the study mean.
    (iii) Beginning April 1, 2007, the laboratory must achieve 
quantitative results on the PE sample analyses that are within the 
following acceptance limits:

------------------------------------------------------------------------
                                      Acceptance
                                        limits
                DBP                   (percent of         Comments
                                      true value)
------------------------------------------------------------------------
TTHM
    Chloroform....................  20  Laboratory must meet
                                                     all 4 individual
                                                     THM acceptance
                                                     limits in order to
                                                     successfully pass a
                                                     PE sample for TTHM
    Bromodichloromethane..........  20  ....................
    Dibromochloromethane..........  20  ....................
    Bromoform.....................  20  ....................
HAA5
    Monochloroacetic Acid.........  40  Laboratory must meet
                                                     the acceptance
                                                     limits for 4 out of
                                                     5 of the HAA5
                                                     compounds in order
                                                     to successfully
                                                     pass a PE sample
                                                     for HAA5
    Dichloroacetic Acid...........  40  ....................
    Trichloroacetic Acid..........  40  ....................
    Monobromoacetic Acid..........  40  ....................
    Dibromoacetic Acid............  40  ....................
Chlorite..........................  30  ....................

[[Page 481]]

 
Bromate...........................  30  ....................
------------------------------------------------------------------------

    (iv) Beginning April 1, 2007, report quantitative data for 
concentrations at least as low as the ones listed in the following 
table for all DBP samples analyzed for compliance with Sec. Sec.  
141.64, 141.135, and subparts U and V of this part:

------------------------------------------------------------------------
                                       Minimum
                                      reporting
                DBP                   level (mg/         Comments
                                        L) \1\
------------------------------------------------------------------------
TTHM \2\
    Chloroform.....................       0.0010
    Bromodichloromethane...........       0.0010
    Dibromochloromethane...........       0.0010
    Bromoform......................       0.0010
HAA5 \2\
    Monochloroacetic Acid..........       0.0020
    Dichloroacetic Acid............       0.0010
    Trichloroacetic Acid...........       0.0010
    Monobromoacetic Acid...........       0.0010
    Dibromoacetic Acid.............       0.0010
Chlorite...........................        0.020  Applicable to
                                                   monitoring as
                                                   prescribed in Sec.
                                                   141.132(b)(2)(1)(B)
                                                   and (b)(2)(ii).
Bromate............................    0.0050 or  Laboratories that use
                                          0.0010   EPA Methods 317.0
                                                   Revision 2.0, 326.0
                                                   or 321.8 must meet a
                                                   0.0010 mg/L MRL for
                                                   bromate.
------------------------------------------------------------------------
\1\ The calibration curve must encompass the regulatory minimum
  reporting level (MRL) concentration. Data may be reported for
  concentrations lower than the regulatory MRL as long as the precision
  and accuracy criteria are met by analyzing an MRL check standard at
  the lowest reporting limit chosen by the laboratory. The laboratory
  must verify the accuracy of the calibration curve at the MRL
  concentration by analyzing an MRL check standard with a concentration
  less than or equal to 110% of the MRL with each batch of samples. The
  measured concentration for the MRL check standard must be 50% of the expected value, if any field sample in the batch has
  a concentration less than 5 times the regulatory MRL. Method
  requirements to analyze higher concentration check standards and meet
  tighter acceptance criteria for them must be met in addition to the
  MRL check standard requirement.
\2\ When adding the individual trihalomethane or haloacetic acid
  concentrations to calculate the TTHM or HAA5 concentrations,
  respectively, a zero is used for any analytical result that is less
  than the MRL concentration for that DBP, unless otherwise specified by
  the State.

* * * * *
    (c) * * *
    (1) * * *

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                    Residual measured 1
           Methodology              SM (19th or 20th       SM  Online 2           ASTM  method           EPA  method     -----------------------------------------------------------------------
                                          ed)                                                                                 Free  Cl2       Combined  Cl2      Total  Cl2           ClO2
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Amperometric Titration..........  4500-C D             4500-C D-00          D 1253-86 (96), 03       ...................  X                 X                 X                 ................
Low Level Amperometric Titration  4500-C E             4500-C E-00          .......................  ...................  ................  ................  X
DPD Ferrous Titrimetric.........  4500-C F             4500-C F-00          .......................  ...................  X                 X                 X                 ................
DPD Colorimetric................  4500-C G             4500-C G-00          .......................  ...................  X                 X                 X                 ................
Syringaldazine (FACTS)..........  4500-C H             4500-C H-00          .......................  ...................  X                 ................  ................  ................
Iodometric Electrode............  4500-C I             4500-C I-00          .......................  ...................  ................  ................  X                 ................
DPD.............................  4500-C O2 D          ...................  .......................  ...................  ................  ................  ................  X
Amperometric Method II..........  4500-C O2 E          4500-C O2 E-00       .......................  ...................  ................  ................  ................  X
Lissamine Green                   ...................  ...................  .......................  327.0 Rev 1.1        ................  ................  ................  X
 Spectrophotometric.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1 X indicates method is approved for measuring specified disinfectant residual. Free chlorine or total chlorine may be measured for demonstrating compliance with the chlorine MRDL and combined
  chlorine, or total chlorine may be measured for demonstrating compliance with the chloramine MRDL.
2 The Standard Methods Online version that is approved is indicated by the last two digits in the method number which is the year of approval by the Standard Method Committee. Standard Methods
  Online are available at http://www.standardmethods.org.

* * * * *
    (d) * * *
    (2) Bromide. EPA Methods 300.0, 300.1, 317.0 Revision 2.0, 326.0, 
or ASTM D 6581-00.
    (3) Total Organic Carbon (TOC). Standard Method 5310 B or 5310 B-00 
(High-Temperature Combustion

[[Page 482]]

Method) or Standard Method 5310 C or 5310 C-00 (Persulfate-Ultraviolet 
or Heated-Persulfate Oxidation Method) or Standard Method 5310 D or 
5310 D-00 (Wet-Oxidation Method) or EPA Method 415.3 Revision 1.1. 
Inorganic carbon must be removed from the samples prior to analysis. 
TOC samples may not be filtered prior to analysis. TOC samples must be 
acidified at the time of sample collection to achieve pH less than or 
equal to 2 with minimal addition of the acid specified in the method or 
by the instrument manufacturer. Acidified TOC samples must be analyzed 
within 28 days.
    (4) * * *
    (i) Dissolved Organic Carbon (DOC). Standard Method 5310 B or 5310 
B-00 (High-Temperature Combustion Method) or Standard Method 5310 C or 
5310 C-00 (Persulfate-Ultraviolet or Heated-Persulfate Oxidation 
Method) or Standard Method 5310 D or 5310 D-00 (Wet-Oxidation Method) 
or EPA Method 415.3 Revision 1.1. DOC samples must be filtered through 
the 0.45 [mu]m pore-diameter filter as soon as practical after 
sampling, not to exceed 48 hours. After filtration, DOC samples must be 
acidified to achieve pH less than or equal to 2 with minimal addition 
of the acid specified in the method or by the instrument manufacturer. 
Acidified DOC samples must be analyzed within 28 days of sample 
collection. Inorganic carbon must be removed from the samples prior to 
analysis. Water passed through the filter prior to filtration of the 
sample must serve as the filtered blank. This filtered blank must be 
analyzed using procedures identical to those used for analysis of the 
samples and must meet the following criteria: DOC < 0.5 mg/L.
    (ii) Ultraviolet Absorption at 254 nm (UV254). Standard 
Method 5910 B or 5910 B-00 (Ultraviolet Absorption Method) or EPA 
Method 415.3 Revision 1.1. UV absorption must be measured at 253.7 nm 
(may be rounded off to 254 nm). Prior to analysis, UV254 
samples must be filtered through a 0.45 [mu]m pore-diameter filter. The 
pH of UV254 samples may not be adjusted. Samples must be 
analyzed as soon as practical after sampling, not to exceed 48 hours.
* * * * *
    (6) Magnesium. All methods allowed in Sec.  141.23(k)(1) for 
measuring magnesium.

0
12. Section 141.132 is amended by:
0
a. Redesignating paragraphs (b)(1)(iii) through (b)(1)(v) as paragraphs 
(b)(1)(iv) through (b)(1)(vi);
0
b. Adding a new paragraph (b)(1)(iii);
0
c. Revising newly redesignated paragraph (b)(1)(iv); and
0
d. Revising paragraph (b)(3)(ii).
    The addition and revisions read as follows:


Sec.  141.132  Monitoring requirements.

* * * * *
    (b) * * *
    (1) * * *
    (iii) Monitoring requirements for source water TOC. In order to 
qualify for reduced monitoring for TTHM and HAA5 under paragraph 
(b)(1)(ii) of this section, subpart H systems not monitoring under the 
provisions of paragraph (d) of this section must take monthly TOC 
samples every 30 days at a location prior to any treatment, beginning 
April 1, 2008 or earlier, if specified by the State. In addition to 
meeting other criteria for reduced monitoring in paragraph (b)(1)(ii) 
of this section, the source water TOC running annual average must be 
<=4.0 mg/L (based on the most recent four quarters of monitoring) on a 
continuing basis at each treatment plant to reduce or remain on reduced 
monitoring for TTHM and HAA5. Once qualified for reduced monitoring for 
TTHM and HAA5 under paragraph (b)(1)(ii) of this section, a system may 
reduce source water TOC monitoring to quarterly TOC samples taken every 
90 days at a location prior to any treatment.
    (iv) Systems on a reduced monitoring schedule may remain on that 
reduced schedule as long as the average of all samples taken in the 
year (for systems which must monitor quarterly) or the result of the 
sample (for systems which must monitor no more frequently than 
annually) is no more than 0.060 mg/L and 0.045 mg/L for TTHMs and HAA5, 
respectively. Systems that do not meet these levels must resume 
monitoring at the frequency identified in paragraph (b)(1)(i) of this 
section (minimum monitoring frequency column) in the quarter 
immediately following the monitoring period in which the system exceeds 
0.060 mg/L or 0.045 mg/L for TTHMs and HAA5, respectively. For systems 
using only ground water not under the direct influence of surface water 
and serving fewer than 10,000 persons, if either the TTHM annual 
average is >0.080 mg/L or the HAA5 annual average is >0.060 mg/L, the 
system must go to the increased monitoring identified in paragraph 
(b)(1)(i) of this section (sample location column) in the quarter 
immediately following the monitoring period in which the system exceeds 
0.080 mg/L or 0.060 mg/L for TTHMs or HAA5 respectively.
* * * * *
    (3) ***
    (i) ***
    (ii) Reduced monitoring.
    (A) Until March 31, 2009, systems required to analyze for bromate 
may reduce monitoring from monthly to quarterly, if the system's 
average source water bromide concentration is less than 0.05 mg/L based 
on representative monthly bromide measurements for one year. The system 
may remain on reduced bromate monitoring until the running annual 
average source water bromide concentration, computed quarterly, is 
equal to or greater than 0.05 mg/L based on representative monthly 
measurements. If the running annual average source water bromide 
concentration is >=0.05 mg/L, the system must resume routine monitoring 
required by paragraph (b)(3)(i) of this section in the following month.
    (B) Beginning April 1, 2009, systems may no longer use the 
provisions of paragraph (b)(3)(ii)(A) of this section to qualify for 
reduced monitoring. A system required to analyze for bromate may reduce 
monitoring from monthly to quarterly, if the system's running annual 
average bromate concentration is <=0.0025 mg/L based on monthly bromate 
measurements under paragraph (b)(3)(i) of this section for the most 
recent four quarters, with samples analyzed using Method 317.0 Revision 
2.0, 326.0 or 321.8. If a system has qualified for reduced bromate 
monitoring under paragraph (b)(3)(ii)(A) of this section, that system 
may remain on reduced monitoring as long as the running annual average 
of quarterly bromate samples <=0.0025 mg/L based on samples analyzed 
using Method 317.0 Revision 2.0, 326.0, or 321.8. If the running annual 
average bromate concentration is >0.0025 mg/L, the system must resume 
routine monitoring required by paragraph (b)(3)(i) of this section.
* * * * *


Sec.  141.133  [Amended]

0
13. Section 141.133 is amended in the last sentence of paragraph (d) by 
revising the reference ``Sec.  141.32'' to read ``subpart Q of this 
part''.

0
14. Section 141.135 is amended by revising paragraph (a)(3)(ii) to read 
as follows:


Sec.  141.135  Treatment technique for control of disinfection 
byproduct (DBP) precursors.

    (a) * * *
    (3) * * *
    (ii) Softening that results in removing at least 10 mg/L of 
magnesium hardness (as CaCO3), measured monthly according to 
Sec.  141.131(d)(6) and calculated quarterly as a running annual 
average.
* * * * *

[[Page 483]]


0
15. Section 141.151 is amended by revising paragraph (d) to read as 
follows:


Sec.  141.151  Purpose and applicability of this subpart.

* * * * *
    (d) For the purpose of this subpart, detected means: at or above 
the levels prescribed by Sec.  141.23(a)(4) for inorganic contaminants, 
at or above the levels prescribed by Sec.  141.24(f)(7) for the 
contaminants listed in Sec.  141.61(a), at or above the levels 
prescribed by Sec.  141.24(h)(18) for the contaminants listed in Sec.  
141.61(c), at or above the levels prescribed by Sec.  141.131(b)(2)(iv) 
for the contaminants or contaminant groups listed in Sec.  141.64, and 
at or above the levels prescribed by Sec.  141.25(c) for radioactive 
contaminants.
* * * * *

0
16. Section 141.153 is amended by revising paragraphs (d)(4)(iv)(B) and 
(d)(4)(iv)(C) to read as follows:


Sec.  141.153  Content of the reports.

* * * * *
    (d) * * *
    (4) * * *
    (iv) * * *
    (B) When compliance with the MCL is determined by calculating a 
running annual average of all samples taken at a monitoring location: 
the highest average of any of the monitoring locations and the range of 
all monitoring locations expressed in the same units as the MCL. For 
the MCLs for TTHM and HAA5 in Sec.  141.64(b)(2), systems must include 
the highest locational running annual average for TTHM and HAA5 and the 
range of individual sample results for all monitoring locations 
expressed in the same units as the MCL. If more than one location 
exceeds the TTHM or HAA5 MCL, the system must include the locational 
running annual averages for all locations that exceed the MCL.
    (C) When compliance with the MCL is determined on a system-wide 
basis by calculating a running annual average of all samples at all 
monitoring locations: the average and range of detection expressed in 
the same units as the MCL. The system is required to include individual 
sample results for the IDSE conducted under subpart U of this part when 
determining the range of TTHM and HAA5 results to be reported in the 
annual consumer confidence report for the calendar year that the IDSE 
samples were taken.
* * * * *

Appendix A to Subpart Q [Amended]

0
17. In Subpart Q, Appendix A is amended as follows:
0
a. In entry I.B.2. in the fifth column, remove the endnote citation 
``9'' and add in its place ``11'';
0
b. In entry I.B.11. in the fourth column, remove the endnote citation 
``10'' and add in its place ``12'';
0
c. In entry I.B.12. in the fourth column, remove the endnote citation 
``10'' and add in its place ``12'';
0
d. In entry I.G. in the first column, remove the endnote citation 
``11'' and add in its place ``13'';
0
e. In entry I.G.1. in the third column, remove the endnote citation 
``12'' and add in its place ``14'' and remove the citation in the third 
column ``141.12, 141.64(a)'' and in its place add ``141.64(b)'' 
(keeping the endnote citation to endnote 14) and in the fifth column 
remove the citation ``141.30'' and add in numerical order the citations 
``141.600-141.605, 141.620-141.629'';
0
f. In entry I.G.2. revise the entry ``141.64(a)'' to read ``141.64(b)'' 
and in the fifth column add in numerical order the citations ``141.600-
141.605, 141.620-141.629''.
0
g. In entry I.G.7. in the fourth column, remove the endnote citation 
``13'' and add in its place ``15'';
0
h. In entry I.G.8. in the second column, remove the endnote citation 
``14'' and add in its place ``16'';
0
i. In entry II. in the first column, remove the endnote citation ``15'' 
and add in its place ``17'';
0
j. In entry III.A. in the third column, remove the endnote citation 
``16'' and add in its place ``18'';
0
k. In entry III.B in the third column, remove the endnote citation 
``17'' and add in its place ``19'';
0
l. In entry IV.E. in the first column, remove the endnote citation 
``18'' and add in its place 20''; and
0
m. In entry III.F in the second column, remove the endnote citation 
``19'' and add in its place ``21''.
0
18. In Subpart Q, Appendix A, remove endnote 14 and add in its place, 
to read as follows: ``14.Sec. Sec.  141.64(b)(1) 141.132(a)-(b) apply 
until Sec. Sec.  141.620-141.630 take effect under the schedule in 
Sec.  141.620(c).

0
19-20. In Subpart Q, Appendix B is amended as follows:
0
a. In entry G.77. in the third column, remove the endnote citation 
``16'' and add in its place ``17'';
0
b. In entry H. (the title) in the first column, remove the endnote 
citation ``17'' and add in its place ``18'';
0
c. In entry H.80. in the third column, remove the endnote citations 
``17, 18'' and add in its place ``19, 20'' and remove the number 
``0.10/'';
0
d. In entry H.81. in the third column, remove the endnote citation 
``20'' and add in its place ``21''; and
0
e. In entry H.84. in the second column, remove the endnote citation 
``21'' and add in its place ``22'' and in the third column remove the 
endnote citation ``22'' and add in its place ``23''.
0
f. Revise endnotes 18 and 19.
    The revisions read as follows:

Appendix B to Subpart Q

* * * * *
0
18. Surface water systems and ground water systems under the direct 
influence of surface water are regulated under subpart H of 40 CFR 141. 
Subpart H community and non-transient non-community systems serving 
>=10,000 must comply with subpart L DBP MCLs and disinfectant maximum 
residual disinfectant levels (MRDLs) beginning January 1, 2002. All 
other community and non-transient non-community systems must comply 
with subpart L DBP MCLs and disinfectant MRDLs beginning January 1, 
2004. Subpart H transient non-community systems serving >=10,000 that 
use chlorine dioxide as a disinfectant or oxidant must comply with the 
chlorine dioxide MRDL beginning January 1, 2002. All other transient 
non-community systems that use chlorine dioxide as a disinfectant or 
oxidant must comply with the chlorine dioxide MRDL beginning January 1, 
2004.
0
19. Community and non-transient non-community systems must comply with 
subpart V TTHM and HAA5 MCLs of 0.080 mg/L and 0.060 mg/L, respectively 
(with compliance calculated as a locational running annual average) on 
the schedule in Sec.  141.620.
* * * * *

0
21. Part 141 is amended by adding new subpart U to read as follows:

Subpart U--Initial Distribution System Evaluations

141.600 General requirements.
141.601 Standard monitoring.
141.602 System specific studies.
141.603 40/30 certification.
141.604 Very small system waivers.
141.605 Subpart V compliance monitoring location recommendations.

Subpart U--Initial Distribution System Evaluations


Sec.  141.600  General requirements.

    (a) The requirements of subpart U of this part constitute national 
primary drinking water regulations. The regulations in this subpart 
establish monitoring and other requirements for identifying subpart V 
compliance monitoring locations for determining compliance with maximum 
contaminant levels for total

[[Page 484]]

trihalomethanes (TTHM) and haloacetic acids (five)(HAA5). You must use 
an Initial Distribution System Evaluation (IDSE) to determine locations 
with representative high TTHM and HAA5 concentrations throughout your 
distribution system. IDSEs are used in conjunction with, but separate 
from, subpart L compliance monitoring, to identify and select subpart V 
compliance monitoring locations.
    (b) Applicability. You are subject to these requirements if your 
system is a community water system that uses a primary or residual 
disinfectant other than ultraviolet light or delivers water that has 
been treated with a primary or residual disinfectant other than 
ultraviolet light; or if your system is a nontransient noncommunity 
water system that serves at least 10,000 people and uses a primary or 
residual disinfectant other than ultraviolet light or delivers water 
that has been treated with a primary or residual disinfectant other 
than ultraviolet light.
    (c) Schedule. (1) You must comply with the requirements of this 
subpart on the schedule in the table in this paragraph (c)(1).

----------------------------------------------------------------------------------------------------------------
                                        You must submit your
                                      standard monitoring plan
                                      or system specific study   You must complete your
                                          plan \1\ or 40/30      standard monitoring or    You must submit your
    If you serve this population      certification \2\ to the   system specific study      IDSE report to the
                                      State by or receive very             by                  State by \3\
                                      small system waiver from
                                                State
----------------------------------------------------------------------------------------------------------------
Systems that are not part of a combined distribution system and systems that serve the largest population in the
                                          combined distribution system
----------------------------------------------------------------------------------------------------------------
(i) >=100,000.......................  October 1, 2006.........  September 30, 2008.....  January 1, 2009.
(ii) 50,000-99,999..................  April 1, 2007...........  March 31, 2009.........  July 1, 2009.
(iii) 10,000-49,999.................  October 1, 2007.........  September 30, 2009.....  January 1, 2010.
(iv) <10,000 (CWS Only).............  April 1, 2008...........  March 31, 2010.........  July 1, 2010.
-------------------------------------
                          Other systems that are part of a combined distribution system
----------------------------------------------------------------------------------------------------------------
(v) Wholesale system or consecutive   --at the same time as     --at the same time as    --at the same time as
 system.                               the system with the       the system with the      the system with the
                                       earliest compliance       earliest compliance      earliest compliance
                                       date in the combined      date in the combined     date in the combined
                                       distribution system.      distribution system.     distribution system.
----------------------------------------------------------------------------------------------------------------
\1\ If, within 12 months after the date identified in this column, the State does not approve your plan or
  notify you that it has not yet completed its review, you may consider the plan that you submitted as approved.
  You must implement that plan and you must complete standard monitoring or a system specific study no later
  than the date identified in the third column.
\2\ You must submit your 40/30 certification under Sec.   141.603 by the date indicated.
\3\ If, within three months after the date identified in this column (nine months after the date identified in
  this column if you must comply on the schedule in paragraph (c)(1)(iii) of this section), the State does not
  approve your IDSE report or notify you that it has not yet completed its review, you may consider the report
  that you submitted as approved and you must implement the recommended subpart V monitoring as required.

    (2) For the purpose of the schedule in paragraph (c)(1) of this 
section, the State may determine that the combined distribution system 
does not include certain consecutive systems based on factors such as 
receiving water from a wholesale system only on an emergency basis or 
receiving only a small percentage and small volume of water from a 
wholesale system. The State may also determine that the combined 
distribution system does not include certain wholesale systems based on 
factors such as delivering water to a consecutive system only on an 
emergency basis or delivering only a small percentage and small volume 
of water to a consecutive system.
    (d) You must conduct standard monitoring that meets the 
requirements in Sec.  141.601, or a system specific study that meets 
the requirements in Sec.  141.602, or certify to the State that you 
meet 40/30 certification criteria under Sec.  141.603, or qualify for a 
very small system waiver under Sec.  141.604.
    (1) You must have taken the full complement of routine TTHM and 
HAA5 compliance samples required of a system with your population and 
source water under subpart L of this part (or you must have taken the 
full complement of reduced TTHM and HAA5 compliance samples required of 
a system with your population and source water under subpart L if you 
meet reduced monitoring criteria under subpart L of this part) during 
the period specified in Sec.  141.603(a) to meet the 40/30 
certification criteria in Sec.  141.603. You must have taken TTHM and 
HAA5 samples under Sec. Sec.  141.131 and 141.132 to be eligible for 
the very small system waiver in Sec.  141.604.
    (2) If you have not taken the required samples, you must conduct 
standard monitoring that meets the requirements in Sec.  141.601, or a 
system specific study that meets the requirements in Sec.  141.602.
    (e) You must use only the analytical methods specified in Sec.  
141.131, or otherwise approved by EPA for monitoring under this 
subpart, to demonstrate compliance with the requirements of this 
subpart.
    (f) IDSE results will not be used for the purpose of determining 
compliance with MCLs in Sec.  141.64.


Sec.  141.601  Standard monitoring.

    (a) Standard monitoring plan. Your standard monitoring plan must 
comply with paragraphs (a)(1) through (a)(4) of this section. You must 
prepare and submit your standard monitoring plan to the State according 
to the schedule in Sec.  141.600(c).
    (1) Your standard monitoring plan must include a schematic of your 
distribution system (including distribution system entry points and 
their sources, and storage facilities), with notes indicating locations 
and dates of all projected standard monitoring, and all projected 
subpart L compliance monitoring.
    (2) Your standard monitoring plan must include justification of 
standard monitoring location selection and a summary of data you relied 
on to justify standard monitoring location selection.
    (3) Your standard monitoring plan must specify the population 
served and system type (subpart H or ground water).
    (4) You must retain a complete copy of your standard monitoring 
plan submitted under this paragraph (a), including any State 
modification of your standard monitoring plan, for as long as

[[Page 485]]

you are required to retain your IDSE report under paragraph (c)(4) of 
this section.
    (b) Standard monitoring. (1) You must monitor as indicated in the 
table in this paragraph (b)(1). You must collect dual sample sets at 
each monitoring location. One sample in the dual sample set must be 
analyzed for TTHM. The other sample in the dual sample set must be 
analyzed for HAA5. You must conduct one monitoring period during the 
peak historical month for TTHM levels or HAA5 levels or the month of 
warmest water temperature. You must review available compliance, study, 
or operational data to determine the peak historical month for TTHM or 
HAA5 levels or warmest water temperature.

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                       Distribution system monitoring locations \1\
                                                                                                 -------------------------------------------------------
            Source water type              Population size category     Monitoring periods and     Total per     Near     Average
                                                                         frequency of sampling    monitoring    entry    residence  High TTHM  High HAA5
                                                                                                    period      points      time    locations  locations
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subpart H
                                          <500 consecutive systems..  one (during peak                     2          1  .........          1
                                                                       historical month) \2\.
                                          <500 non-consecutive        ..........................           2  .........  .........          1          1
                                           systems.
                                          500-3,300 consecutive       four (every 90 days)......           2          1  .........          1
                                           systems.
                                          500-3,300 non-consecutive   ..........................           2  .........  .........          1          1
                                           systems.
                                          3,301-9,999...............  ..........................           4  .........          1          2          1
                                          10,000-49,999.............  six (every 60 days).......           8          1          2          3          2
                                          50,000-249,999............  ..........................          16          3          4          5          4
                                          250,000-999,999...........  ..........................          24          4          6          8          6
                                          1,000,000-4,999,999.......  ..........................          32          6          8         10          8
                                          >=5,000,000...............  ..........................          40          8         10         12         10
Ground Water
                                          <500 consecutive systems..  one (during peak                     2          1  .........          1
                                                                       historical month) \2\.
                                          <500 non-consecutive        ..........................           2  .........  .........          1          1
                                           systems.
                                          500-9,999.................  four (every 90 days)......           2  .........  .........          1          1
                                          10,000-99,999.............  ..........................           6          1          1          2          2
                                          100,000-499,999...........  ..........................           8          1          1          3          3
                                          >=500,000.................  ..........................          12          2          2          4          4
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ A dual sample set (i.e., a TTHM and an HAA5 sample) must be taken at each monitoring location during each monitoring period.
\2\ The peak historical month is the month with the highest TTHM or HAA5 levels or the warmest water temperature.

    (2) You must take samples at locations other than the existing 
subpart L monitoring locations. Monitoring locations must be 
distributed throughout the distribution system.
    (3) If the number of entry points to the distribution system is 
fewer than the specified number of entry point monitoring locations, 
excess entry point samples must be replaced equally at high TTHM and 
HAA5 locations. If there is an odd extra location number, you must take 
a sample at a high TTHM location. If the number of entry points to the 
distribution system is more than the specified number of entry point 
monitoring locations, you must take samples at entry points to the 
distribution system having the highest annual water flows.
    (4) Your monitoring under this paragraph (b) may not be reduced 
under the provisions of Sec.  141.29 and the State may not reduce your 
monitoring using the provisions of Sec.  142.16(m).
    (c) IDSE report. Your IDSE report must include the elements 
required in paragraphs (c)(1) through (c)(4) of this section. You must 
submit your IDSE report to the State according to the schedule in Sec.  
141.600(c).
    (1) Your IDSE report must include all TTHM and HAA5 analytical 
results from subpart L compliance monitoring and all standard 
monitoring conducted during the period of the IDSE as individual 
analytical results and LRAAs presented in a tabular or spreadsheet 
format acceptable to the State. If changed from your standard 
monitoring plan submitted under paragraph (a) of this section, your 
report must also include a schematic of your distribution system, the 
population served, and system type (subpart H or ground water).
    (2) Your IDSE report must include an explanation of any deviations 
from your approved standard monitoring plan.
    (3) You must recommend and justify subpart V compliance monitoring 
locations and timing based on the protocol in Sec.  141.605.
    (4) You must retain a complete copy of your IDSE report submitted 
under this section for 10 years after the date that you submitted your 
report. If the State modifies the subpart V monitoring requirements 
that you recommended in your IDSE report or if the State approves 
alternative monitoring locations, you must keep a copy of the State's 
notification on file for 10 years after the date of the State's 
notification. You must make the IDSE report and any State notification 
available for review by the State or the public.


Sec.  141.602  System specific studies.

    (a) System specific study plan. Your system specific study plan 
must be based on either existing monitoring results as required under 
paragraph (a)(1) of this section or modeling as required under 
paragraph (a)(2) of this section. You must prepare and submit your 
system specific study plan to the State according to the schedule in 
Sec.  141.600(c).
    (1) Existing monitoring results. You may comply by submitting 
monitoring results collected before you are required to begin 
monitoring under Sec.  141.600(c). The monitoring results and analysis 
must meet the criteria in paragraphs (a)(1)(i) and (a)(1)(ii) of this 
section.
    (i) Minimum requirements. (A) TTHM and HAA5 results must be based 
on samples collected and analyzed in accordance with Sec.  141.131. 
Samples must be collected no earlier than five years prior to the study 
plan submission date.

[[Page 486]]

    (B) The monitoring locations and frequency must meet the conditions 
identified in this paragraph (a)(1)(i)(B). Each location must be 
sampled once during the peak historical month for TTHM levels or HAA5 
levels or the month of warmest water temperature for every 12 months of 
data submitted for that location. Monitoring results must include all 
subpart L compliance monitoring results plus additional monitoring 
results as necessary to meet minimum sample requirements.

----------------------------------------------------------------------------------------------------------------
                                                                               Number of      Number of samples
                        System Type                           Population      monitoring   ---------------------
                                                             size category     locations       TTHM       HAA5
----------------------------------------------------------------------------------------------------------------
Subpart H:
                                                                      <500               3          3          3
                                                                 500-3,300               3          9          9
                                                               3,301-9,999               6         36         36
                                                             10,000-49,999              12         72         72
                                                            50,000-249,999              24        144        144
                                                            250,000-999,99              36        216        216
                                                                         9
                                                            1,000,000-4,99              48        288        288
                                                                     9,999
                                                              >= 5,000,000              60        360        360
Ground Water:
                                                                      <500               3          3          3
                                                                 500-9,999               3          9          9
                                                             10,000-99,999              12         48         48
                                                            100,000-499,99              18         72         72
                                                                         9
                                                                >= 500,000              24         96         96
----------------------------------------------------------------------------------------------------------------

    (ii) Reporting monitoring results. You must report the information 
in this paragraph (a)(1)(ii).
    (A) You must report previously collected monitoring results and 
certify that the reported monitoring results include all compliance and 
non-compliance results generated during the time period beginning with 
the first reported result and ending with the most recent subpart L 
results.
    (B) You must certify that the samples were representative of the 
entire distribution system and that treatment, and distribution system 
have not changed significantly since the samples were collected.
    (C) Your study monitoring plan must include a schematic of your 
distribution system (including distribution system entry points and 
their sources, and storage facilities), with notes indicating the 
locations and dates of all completed or planned system specific study 
monitoring.
    (D) Your system specific study plan must specify the population 
served and system type (subpart H or ground water).
    (E) You must retain a complete copy of your system specific study 
plan submitted under this paragraph (a)(1), including any State 
modification of your system specific study plan, for as long as you are 
required to retain your IDSE report under paragraph (b)(5) of this 
section.
    (F) If you submit previously collected data that fully meet the 
number of samples required under paragraph (a)(1)(i)(B) of this section 
and the State rejects some of the data, you must either conduct 
additional monitoring to replace rejected data on a schedule the State 
approves or conduct standard monitoring under Sec.  141.601.
    (2) Modeling. You may comply through analysis of an extended period 
simulation hydraulic model. The extended period simulation hydraulic 
model and analysis must meet the criteria in this paragraph (a)(2).
    (i) Minimum requirements. (A) The model must simulate 24 hour 
variation in demand and show a consistently repeating 24 hour pattern 
of residence time.
    (B) The model must represent the criteria listed in paragraphs 
(a)(2)(i)(B)(1) through (9) of this section.
    (1) 75% of pipe volume;
    (2) 50% of pipe length;
    (3) All pressure zones;
    (4) All 12-inch diameter and larger pipes;
    (5) All 8-inch and larger pipes that connect pressure zones, 
influence zones from different sources, storage facilities, major 
demand areas, pumps, and control valves, or are known or expected to be 
significant conveyors of water;
    (6) All 6-inch and larger pipes that connect remote areas of a 
distribution system to the main portion of the system;
    (7) All storage facilities with standard operations represented in 
the model; and
    (8) All active pump stations with controls represented in the 
model; and
    (9) All active control valves.
    (C) The model must be calibrated, or have calibration plans, for 
the current configuration of the distribution system during the period 
of high TTHM formation potential. All storage facilities must be 
evaluated as part of the calibration process. All required calibration 
must be completed no later than 12 months after plan submission.
    (ii) Reporting modeling. Your system specific study plan must 
include the information in this paragraph (a)(2)(ii).
    (A) Tabular or spreadsheet data demonstrating that the model meets 
requirements in paragraph (a)(2)(i)(B) of this section.
    (B) A description of all calibration activities undertaken, and if 
calibration is complete, a graph of predicted tank levels versus 
measured tank levels for the storage facility with the highest 
residence time in each pressure zone, and a time series graph of the 
residence time at the longest residence time storage facility in the 
distribution system showing the predictions for the entire simulation 
period (i.e., from time zero until the time it takes to for the model 
to reach a consistently repeating pattern of residence time).
    (C) Model output showing preliminary 24 hour average residence time 
predictions throughout the distribution system.
    (D) Timing and number of samples representative of the distribution 
system planned for at least one monitoring period of TTHM and HAA5 dual 
sample monitoring at a number of locations no

[[Page 487]]

less than would be required for the system under standard monitoring in 
Sec.  141.601 during the historical month of high TTHM. These samples 
must be taken at locations other than existing subpart L compliance 
monitoring locations.
    (E) Description of how all requirements will be completed no later 
than 12 months after you submit your system specific study plan.
    (F) Schematic of your distribution system (including distribution 
system entry points and their sources, and storage facilities), with 
notes indicating the locations and dates of all completed system 
specific study monitoring (if calibration is complete) and all subpart 
L compliance monitoring.
    (G) Population served and system type (subpart H or ground water).
    (H) You must retain a complete copy of your system specific study 
plan submitted under this paragraph (a)(2), including any State 
modification of your system specific study plan, for as long as you are 
required to retain your IDSE report under paragraph (b)(7) of this 
section.
    (iii) If you submit a model that does not fully meet the 
requirements under paragraph (a)(2) of this section, you must correct 
the deficiencies and respond to State inquiries concerning the model. 
If you fail to correct deficiencies or respond to inquiries to the 
State's satisfaction, you must conduct standard monitoring under Sec.  
141.601.
    (b) IDSE report. Your IDSE report must include the elements 
required in paragraphs (b)(1) through (b)(6) of this section. You must 
submit your IDSE report according to the schedule in Sec.  141.600(c).
    (1) Your IDSE report must include all TTHM and HAA5 analytical 
results from subpart L compliance monitoring and all system specific 
study monitoring conducted during the period of the system specific 
study presented in a tabular or spreadsheet format acceptable to the 
State. If changed from your system specific study plan submitted under 
paragraph (a) of this section, your IDSE report must also include a 
schematic of your distribution system, the population served, and 
system type (subpart H or ground water).
    (2) If you used the modeling provision under paragraph (a)(2) of 
this section, you must include final information for the elements 
described in paragraph (a)(2)(ii) of this section, and a 24-hour time 
series graph of residence time for each subpart V compliance monitoring 
location selected.
    (3) You must recommend and justify subpart V compliance monitoring 
locations and timing based on the protocol in Sec.  141.605.
    (4) Your IDSE report must include an explanation of any deviations 
from your approved system specific study plan.
    (5) Your IDSE report must include the basis (analytical and 
modeling results) and justification you used to select the recommended 
subpart V monitoring locations.
    (6) You may submit your IDSE report in lieu of your system specific 
study plan on the schedule identified in Sec.  141.600(c) for 
submission of the system specific study plan if you believe that you 
have the necessary information by the time that the system specific 
study plan is due. If you elect this approach, your IDSE report must 
also include all information required under paragraph (a) of this 
section.
    (7) You must retain a complete copy of your IDSE report submitted 
under this section for 10 years after the date that you submitted your 
IDSE report. If the State modifies the subpart V monitoring 
requirements that you recommended in your IDSE report or if the State 
approves alternative monitoring locations, you must keep a copy of the 
State's notification on file for 10 years after the date of the State's 
notification. You must make the IDSE report and any State notification 
available for review by the State or the public.


Sec.  141.603  40/30 certification.

    (a) Eligibility. You are eligible for 40/30 certification if you 
had no TTHM or HAA5 monitoring violations under subpart L of this part 
and no individual sample exceeded 0.040 mg/L for TTHM or 0.030 mg/L for 
HAA5 during an eight consecutive calendar quarter period beginning no 
earlier than the date specified in this paragraph (a).

------------------------------------------------------------------------
                                         Then your eligibility for 40/30
                                         certification is based on eight
                                          consecutive calendar quarters
   If your 40/30 certification is due        of subpart L compliance
                                         monitoring results beginning no
                                                 earlier than \1\
------------------------------------------------------------------------
(1) October 1, 2006....................  January 2004.
(2) April 1, 2007......................  January 2004.
(3) October 1, 2007....................  January 2005.
(4) April 1, 2008......................  January 2005.
------------------------------------------------------------------------
\1\ Unless you are on reduced monitoring under subpart L of this part
  and were not required to monitor during the specified period. If you
  did not monitor during the specified period, you must base your
  eligibility on compliance samples taken during the 12 months preceding
  the specified period.

    (b) 40/30 certification. (1) You must certify to your State that 
every individual compliance sample taken under subpart L of this part 
during the periods specified in paragraph (a) of this section were 
<=0.040 mg/L for TTHM and <=0.030 mg/L for HAA5, and that you have not 
had any TTHM or HAA5 monitoring violations during the period specified 
in paragraph (a) of this section.
    (2) The State may require you to submit compliance monitoring 
results, distribution system schematics, and/or recommended subpart V 
compliance monitoring locations in addition to your certification. If 
you fail to submit the requested information, the State may require 
standard monitoring under Sec.  141.601 or a system specific study 
under Sec.  141.602.
    (3) The State may still require standard monitoring under Sec.  
141.601 or a system specific study under Sec.  141.602 even if you meet 
the criteria in paragraph (a) of this section.
    (4) You must retain a complete copy of your certification submitted 
under this section for 10 years after the date that you submitted your 
certification. You must make the certification, all data upon which the 
certification is based, and any State notification available for review 
by the State or the public.


Sec.  141.604  Very small system waivers.

    (a) If you serve fewer than 500 people and you have taken TTHM and 
HAA5 samples under subpart L of this part, you are not required to 
comply with this subpart unless the State notifies you that you must 
conduct standard monitoring under Sec.  141.601 or a system specific 
study under Sec.  141.602.
    (b) If you have not taken TTHM and HAA5 samples under subpart L of 
this part or if the State notifies you that you must comply with this 
subpart, you must conduct standard monitoring under Sec.  141.601 or a 
system specific study under Sec.  141.602.


Sec.  141.605  Subpart V compliance monitoring location 
recommendations.

    (a) Your IDSE report must include your recommendations and 
justification for where and during what month(s) TTHM and HAA5 
monitoring for subpart V of this part should be conducted. You must 
base your recommendations on the criteria in paragraphs (b) through (e) 
of this section.
    (b) You must select the number of monitoring locations specified in 
the table in this paragraph (b). You will use these recommended 
locations as subpart V routine compliance monitoring locations, unless 
State requires different

[[Page 488]]

or additional locations. You should distribute locations throughout the 
distribution system to the extent possible.

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                            Distribution system monitoring location
                                                                                                     ---------------------------------------------------
                                                                                                                                               Existing
            Source water type               Population size category      Monitoring frequency \1\     Total per     Highest      Highest     subpart L
                                                                                                       monitoring      TTHM         HAA5      compliance
                                                                                                       period \2\   locations    locations    locations
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subpart H:
                                          <500                          per year                                2            1            1  ...........
                                          500-3,300                     per quarter                             2            1            1
                                          3,301-9,999                   per quarter                             2            1            1  ...........
                                          10,000-49,999                 per quarter                             4            2            1            1
                                          50,000-249,999                per quarter                             8            3            3            2
                                          250,000-999,999               per quarter                            12            5            4            3
                                          1,000,000-4,999,999           per quarter                            16            6            6            4
                                          >=5,000,000                   per quarter                            20            8            7            5
Ground water:
                                          <500                          per year                                2            1            1
                                          500-9,999                     per year                                2            1            1
                                          10,000-99,999                 per quarter                             4            2            1            1
                                          100,000-499,999               per quarter                             6            3            2            1
                                          >=500,000                     per quarter                             8            3            3           2
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ All systems must monitor during month of highest DBP concentrations.
\2\ Systems on quarterly monitoring must take dual sample sets every 90 days at each monitoring location, except for subpart H systems serving 500-
  3,300. Systems on annual monitoring and subpart H systems serving 500-3,300 are required to take individual TTHM and HAA5 samples (instead of a dual
  sample set) at the locations with the highest TTHM and HAA5 concentrations, respectively. Only one location with a dual sample set per monitoring
  period is needed if highest TTHM and HAA5 concentrations occur at the same location, and month, if monitored annually).

    (c) You must recommend subpart V compliance monitoring locations 
based on standard monitoring results, system specific study results, 
and subpart L compliance monitoring results. You must follow the 
protocol in paragraphs (c)(1) through (c)(8) of this section. If 
required to monitor at more than eight locations, you must repeat the 
protocol as necessary. If you do not have existing subpart L compliance 
monitoring results or if you do not have enough existing subpart L 
compliance monitoring results, you must repeat the protocol, skipping 
the provisions of paragraphs (c)(3) and (c)(7) of this section as 
necessary, until you have identified the required total number of 
monitoring locations.
    (1) Location with the highest TTHM LRAA not previously selected as 
a subpart V monitoring location.
    (2) Location with the highest HAA5 LRAA not previously selected as 
a subpart V monitoring location.
    (3) Existing subpart L average residence time compliance monitoring 
location (maximum residence time compliance monitoring location for 
ground water systems) with the highest HAA5 LRAA not previously 
selected as a subpart V monitoring location.
    (4) Location with the highest TTHM LRAA not previously selected as 
a subpart V monitoring location.
    (5) Location with the highest TTHM LRAA not previously selected as 
a subpart V monitoring location.
    (6) Location with the highest HAA5 LRAA not previously selected as 
a subpart V monitoring location.
    (7) Existing subpart L average residence time compliance monitoring 
location (maximum residence time compliance monitoring location for 
ground water systems) with the highest TTHM LRAA not previously 
selected as a subpart V monitoring location.
    (8) Location with the highest HAA5 LRAA not previously selected as 
a subpart V monitoring location.
    (d) You may recommend locations other than those specified in 
paragraph (c) of this section if you include a rationale for selecting 
other locations. If the State approves the alternate locations, you 
must monitor at these locations to determine compliance under subpart V 
of this part.
    (e) Your recommended schedule must include subpart V monitoring 
during the peak historical month for TTHM and HAA5 concentration, 
unless the State approves another month. Once you have identified the 
peak historical month, and if you are required to conduct routine 
monitoring at least quarterly, you must schedule subpart V compliance 
monitoring at a regular frequency of every 90 days or fewer.

0
20. Part 141 is amended by adding new subpart V to read as follows:

Subpart V--Stage 2 Disinfection Byproducts Requirements

141.620 General requirements.
141.621 Routine monitoring.
141.622 Subpart V monitoring plan.
141.623 Reduced monitoring.
141.624 Additional requirements for consecutive systems.
141.625 Conditions requiring increased monitoring.
141.626 Operational evaluation levels.
141.627 Requirements for remaining on reduced TTHM and HAA5 
monitoring based on subpart L results.
141.628 Requirements for remaining on increased TTHM and HAA5 
monitoring based on subpart L results.
141.629 Reporting and recordkeeping requirements.

Subpart V--Stage 2 Disinfection Byproducts Requirements


Sec.  141.620  General requirements.

    (a) General. The requirements of subpart V of this part constitute 
national primary drinking water regulations. The regulations in this 
subpart establish monitoring and other requirements for

[[Page 489]]

achieving compliance with maximum contaminant levels based on 
locational running annual averages (LRAA) for total trihalomethanes 
(TTHM) and haloacetic acids (five)(HAA5), and for achieving compliance 
with maximum residual disinfectant residuals for chlorine and 
chloramine for certain consecutive systems.
    (b) Applicability. You are subject to these requirements if your 
system is a community water system or a nontransient noncommunity water 
system that uses a primary or residual disinfectant other than 
ultraviolet light or delivers water that has been treated with a 
primary or residual disinfectant other than ultraviolet light.
    (c) Schedule. You must comply with the requirements in this subpart 
on the schedule in the following table based on your system type.

------------------------------------------------------------------------
                                       You must comply with subpart V
  If you are this type of system             monitoring by: \1\
------------------------------------------------------------------------
 Systems that are not part of a combined distribution system and systems
  that serve the largest population in the combined distribution system
------------------------------------------------------------------------
(1) System serving >= 100,000.....  April 1, 2012.
(2) System serving 50,000-99,999..  October 1, 2012.
(3) System serving 10,000-49,999..  October 1, 2013.
(4) System serving > 10,000.......  October 1, 2013 if no
                                     Cryptosporidium monitoring is
                                     required under Sec.   141.701(a)(4)
                                     or
                                    October 1, 2014 if Cryptosporidium
                                     monitoring is required under Sec.
                                     141.701(a)(4) or (a)(6)
-----------------------------------
      Other systems that are part of a combined distribution system
------------------------------------------------------------------------
(5) Consecutive system or           --at the same time as the system
 wholesale system.                   with the earliest compliance date
                                     in the combined distribution
                                     system.
------------------------------------------------------------------------
\1\ The State may grant up to an additional 24 months for compliance
  with MCLs and operational evaluaton levels if you require capital
  improvements to comply with an MCL.

    (6) Your monitoring frequency is specified in Sec.  141.621(a)(2).
    (i) If you are required to conduct quarterly monitoring, you must 
begin monitoring in the first full calendar quarter that includes the 
compliance date in the table in this paragraph (c).
    (ii) If you are required to conduct monitoring at a frequency that 
is less than quarterly, you must begin monitoring in the calendar month 
recommended in the IDSE report prepared under Sec.  141.601 or Sec.  
141.602 or the calendar month identified in the subpart V monitoring 
plan developed under Sec.  141.622 no later than 12 months after the 
compliance date in this table.
    (7) If you are required to conduct quarterly monitoring, you must 
make compliance calculations at the end of the fourth calendar quarter 
that follows the compliance date and at the end of each subsequent 
quarter (or earlier if the LRAA calculated based on fewer than four 
quarters of data would cause the MCL to be exceeded regardless of the 
monitoring results of subsequent quarters). If you are required to 
conduct monitoring at a frequency that is less than quarterly, you must 
make compliance calculations beginning with the first compliance sample 
taken after the compliance date.
    (8) For the purpose of the schedule in this paragraph (c), the 
State may determine that the combined distribution system does not 
include certain consecutive systems based on factors such as receiving 
water from a wholesale system only on an emergency basis or receiving 
only a small percentage and small volume of water from a wholesale 
system. The State may also determine that the combined distribution 
system does not include certain wholesale systems based on factors such 
as delivering water to a consecutive system only on an emergency basis 
or delivering only a small percentage and small volume of water to a 
consecutive system.
    (d) Monitoring and compliance. (1) Systems required to monitor 
quarterly. To comply with subpart V MCLs in Sec.  141.64(b)(2), you 
must calculate LRAAs for TTHM and HAA5 using monitoring results 
collected under this subpart and determine that each LRAA does not 
exceed the MCL. If you fail to complete four consecutive quarters of 
monitoring, you must calculate compliance with the MCL based on the 
average of the available data from the most recent four quarters. If 
you take more than one sample per quarter at a monitoring location, you 
must average all samples taken in the quarter at that location to 
determine a quarterly average to be used in the LRAA calculation.
    (2) Systems required to monitor yearly or less frequently. To 
determine compliance with subpart V MCLs in Sec.  141.64(b)(2), you 
must determine that each sample taken is less than the MCL. If any 
sample exceeds the MCL, you must comply with the requirements of Sec.  
141.625. If no sample exceeds the MCL, the sample result for each 
monitoring location is considered the LRAA for that monitoring 
location.
    (e) Violation. You are in violation of the monitoring requirements 
for each quarter that a monitoring result would be used in calculating 
an LRAA if you fail to monitor.


Sec.  141.621  Routine monitoring.

    (a) Monitoring. (1) If you submitted an IDSE report, you must begin 
monitoring at the locations and months you have recommended in your 
IDSE report submitted under Sec.  141.605 following the schedule in 
Sec.  141.620(c), unless the State requires other locations or 
additional locations after its review. If you submitted a 40/30 
certification under Sec.  141.603 or you qualified for a very small 
system waiver under Sec.  141.604 or you are a nontransient 
noncommunity water system serving <10,000, you must monitor at the 
location(s) and dates identified in your monitoring plan in Sec.  
141.132(f), updated as required by Sec.  141.622.
    (2) You must monitor at no fewer than the number of locations 
identified in this paragraph (a)(2).

[[Page 490]]



----------------------------------------------------------------------------------------------------------------
                                                                                                   Distribution
                                                                                                      system
                                                                                                    monitoring
            Source water type              Population size category    Monitoring Frequency \1\   location total
                                                                                                  per monitoring
                                                                                                    period \2\
----------------------------------------------------------------------------------------------------------------
Subpart H:
                                          <500......................  per year..................               2
                                          500-3,300.................  per quarter...............               2
                                          3,301-9,999...............  per quarter...............               2
                                          10,000-49,999.............  per quarter...............               4
                                          50,000-249,999............  per quarter...............               8
                                          250,000-999,999...........  per quarter...............              12
                                          1,000,000-4,999,999.......  per quarter...............              16
                                          >= 5,000,000..............  per quarter...............              20
Ground Water:
                                          <500......................  per year..................               2
                                          500-9,999.................  per year..................               2
                                          10,000-99,999.............  per quarter...............               4
                                          100,000-499,999...........  per quarter...............               6
                                          >= 500,000................  per quarter...............               8
----------------------------------------------------------------------------------------------------------------
\1\ All systems must monitor during month of highest DBP concentrations.
\2\ Systems on quarterly monitoring must take dual sample sets every 90 days at each monitoring location, except
  for subpart H systems serving 500-3,300. Systems on annual monitoring and subpart H systems serving 500-3,300
  are required to take individual TTHM and HAA5 samples (instead of a dual sample set) at the locations with the
  highest TTHM and HAA5 concentrations, respectively. Only one location with a dual sample set per monitoring
  period is needed if highest TTHM and HAA5 concentrations occur at the same location (and month, if monitored
  annually).

    (3) If you are an undisinfected system that begins using a 
disinfectant other than UV light after the dates in subpart U of this 
part for complying with the Initial Distribution System Evaluation 
requirements, you must consult with the State to identify compliance 
monitoring locations for this subpart. You must then develop a 
monitoring plan under Sec.  141.622 that includes those monitoring 
locations.
    (b) Analytical methods. You must use an approved method listed in 
Sec.  141.131 for TTHM and HAA5 analyses in this subpart. Analyses must 
be conducted by laboratories that have received certification by EPA or 
the State as specified in Sec.  141.131.


Sec.  141.622  Subpart V monitoring plan.

    (a)(1) You must develop and implement a monitoring plan to be kept 
on file for State and public review. The monitoring plan must contain 
the elements in paragraphs (a)(1)(i) through (a)(1)(iv) of this section 
and be complete no later than the date you conduct your initial 
monitoring under this subpart.
    (i) Monitoring locations;
    (ii) Monitoring dates;
    (iii) Compliance calculation procedures; and
    (iv) Monitoring plans for any other systems in the combined 
distribution system if the State has reduced monitoring requirements 
under the State authority in Sec.  142.16(m).
    (2) If you were not required to submit an IDSE report under either 
Sec.  141.601 or Sec.  141.602, and you do not have sufficient subpart 
L monitoring locations to identify the required number of subpart V 
compliance monitoring locations indicated in Sec.  141.605(b), you must 
identify additional locations by alternating selection of locations 
representing high TTHM levels and high HAA5 levels until the required 
number of compliance monitoring locations have been identified. You 
must also provide the rationale for identifying the locations as having 
high levels of TTHM or HAA5. If you have more subpart L monitoring 
locations than required for subpart V compliance monitoring in Sec.  
141.605(b), you must identify which locations you will use for subpart 
V compliance monitoring by alternating selection of locations 
representing high TTHM levels and high HAA5 levels until the required 
number of subpart V compliance monitoring locations have been 
identified.
    (b) If you are a subpart H system serving > 3,300 people, you must 
submit a copy of your monitoring plan to the State prior to the date 
you conduct your initial monitoring under this subpart, unless your 
IDSE report submitted under subpart U of this part contains all the 
information required by this section.
    (c) You may revise your monitoring plan to reflect changes in 
treatment, distribution system operations and layout (including new 
service areas), or other factors that may affect TTHM or HAA5 
formation, or for State-approved reasons, after consultation with the 
State regarding the need for changes and the appropriateness of 
changes. If you change monitoring locations, you must replace existing 
compliance monitoring locations with the lowest LRAA with new locations 
that reflect the current distribution system locations with expected 
high TTHM or HAA5 levels. The State may also require modifications in 
your monitoring plan. If you are a subpart H system serving > 3,300 
people, you must submit a copy of your modified monitoring plan to the 
State prior to the date you are required to comply with the revised 
monitoring plan.


Sec.  141.623  Reduced monitoring.

    (a) You may reduce monitoring to the level specified in the table 
in this paragraph (a) any time the LRAA is <=0.040 mg/L for TTHM and 
<=0.030 mg/L for HAA5 at all monitoring locations. You may only use 
data collected under the provisions of this subpart or subpart L of 
this part to qualify for reduced monitoring. In addition, the source 
water annual average TOC level, before any treatment, must be <=4.0 mg/
L at each treatment plant treating surface water or ground water under 
the direct influence of surface water, based on monitoring conducted 
under either Sec.  141.132(b)(1)(iii) or Sec.  141.132(d).

[[Page 491]]



----------------------------------------------------------------------------------------------------------------
                                                                                          Distribution system
            Source water type               Population     Monitoring frequency \1\     monitoring location per
                                           size category                                   monitoring period
----------------------------------------------------------------------------------------------------------------
Subpart H:
                                                    <500  ..........................  monitoring may not be
                                                                                       reduced.
                                               500-3,300  per year..................  1 TTHM and 1 HAA5 sample:
                                                                                       one at the location and
                                                                                       during the quarter with
                                                                                       the highest TTHM single
                                                                                       measurement, one at the
                                                                                       location and during the
                                                                                       quarter with the highest
                                                                                       HAA5 single measurement;
                                                                                       1 dual sample set per
                                                                                       year if the highest TTHM
                                                                                       and HAA5 measurements
                                                                                       occurred at the same
                                                                                       location and quarter.
                                             3,301-9,999  per year..................  2 dual sample sets: one at
                                                                                       the location and during
                                                                                       the quarter with the
                                                                                       highest TTHM single
                                                                                       measurement, one at the
                                                                                       location and during the
                                                                                       quarter with the highest
                                                                                       HAA5 single measurement.
                                           10,000-49,999  per quarter...............  2 dual sample sets at the
                                                                                       locations with the
                                                                                       highest TTHM and highest
                                                                                       HAA5 LRAAs.
                                          50,000-249,999  per quarter...............  4 dual sample sets--at the
                                                                                       locations with the two
                                                                                       highest TTHM and two
                                                                                       highest HAA5 LRAAs.
                                          250,000-999,99  per quarter...............  6 dual sample sets--at the
                                                       9                               locations with the three
                                                                                       highest TTHM and three
                                                                                       highest HAA5 LRAAs.
                                          1,000,000-4,99  per quarter...............  8 dual sample sets--at the
                                                   9,999                               locations with the four
                                                                                       highest TTHM and four
                                                                                       highest HAA5 LRAAs.
                                            >= 5,000,000  per quarter...............  10 dual sample sets--at
                                                                                       the locations with the
                                                                                       five highest TTHM and
                                                                                       five highest HAA5 LRAAs.
Ground Water:
                                                    <500  every third year..........  1 TTHM and 1 HAA5 sample:
                                                                                       one at the location and
                                                                                       during the quarter with
                                                                                       the highest TTHM single
                                                                                       measurement, one at the
                                                                                       location and during the
                                                                                       quarter with the highest
                                                                                       HAA5 single measurement;
                                                                                       1 dual sample set per
                                                                                       year if the highest TTHM
                                                                                       and HAA5 measurements
                                                                                       occurred at the same
                                                                                       location and quarter.
                                               500-9,999  per year..................  1 TTHM and 1 HAA5 sample:
                                                                                       one at the location and
                                                                                       during the quarter with
                                                                                       the highest TTHM single
                                                                                       measurement, one at the
                                                                                       location and during the
                                                                                       quarter with the highest
                                                                                       HAA5 single measurement;
                                                                                       1 dual sample set per
                                                                                       year if the highest TTHM
                                                                                       and HAA5 measurements
                                                                                       occurred at the same
                                                                                       location and quarter.
                                           10,000-99,999  per year..................  2 dual sample sets: one at
                                                                                       the location and during
                                                                                       the quarter with the
                                                                                       highest TTHM single
                                                                                       measurement, one at the
                                                                                       location and during the
                                                                                       quarter with the highest
                                                                                       HAA5 single measurement.
                                          100,000-499,99  per quarter...............  2 dual sample sets; at the
                                                       9                               locations with the
                                                                                       highest TTHM and highest
                                                                                       HAA5 LRAAs.
                                              >= 500,000  per quarter...............  4 dual sample sets at the
                                                                                       locations with the two
                                                                                       highest TTHM and two
                                                                                       highest HAA5 LRAAs.
----------------------------------------------------------------------------------------------------------------
\1\ Systems on quarterly monitoring must take dual sample sets every 90 days.

    (b) You may remain on reduced monitoring as long as the TTHM LRAA 
<=0.040 mg/L and the HAA5 LRAA <=0.030 mg/L at each monitoring location 
(for systems with quarterly reduced monitoring) or each TTHM sample 
<=0.060 mg/L and each HAA5 sample <=0.045 mg/L (for systems with annual 
or less frequent monitoring). In addition, the source water annual 
average TOC level, before any treatment, must be <=4.0 mg/L at each 
treatment plant treating surface water or ground water under the direct 
influence of surface water, based on monitoring conducted under either 
Sec.  141.132(b)(1)(iii) or Sec.  141.132(d).
    (c) If the LRAA based on quarterly monitoring at any monitoring 
location exceeds either 0.040 mg/L for TTHM or 0.030 mg/L for HAA5 or 
if the annual (or less frequent) sample at any location exceeds either 
0.060 mg/L for TTHM or 0.045 mg/L for HAA5, or if the source water 
annual average TOC level, before any treatment, >4.0 mg/L at any 
treatment plant treating surface water or ground water under the direct 
influence of surface water, you must resume routine monitoring under 
Sec.  141.621 or begin increased monitoring if Sec.  141.625 applies.
    (d) The State may return your system to routine monitoring at the 
State's discretion.


Sec.  141.624  Additional requirements for consecutive systems.

    If you are a consecutive system that does not add a disinfectant 
but delivers water that has been treated with a primary or residual 
disinfectant other than ultraviolet light, you must comply with 
analytical and monitoring requirements for chlorine and chloramines in 
Sec.  141.131 (c) and Sec.  141.132(c)(1) and the compliance 
requirements in Sec.  141.133(c)(1) beginning April 1, 2009, unless 
required earlier by the State, and report monitoring results under 
Sec.  141.134(c).


Sec.  141.625  Conditions requiring increased monitoring.

    (a) If you are required to monitor at a particular location 
annually or less frequently than annually under Sec.  141.621 or Sec.  
141.623, you must increase monitoring to dual sample sets once per 
quarter (taken every 90 days) at all locations if a TTHM sample is 
>0.080 mg/L or a HAA5 sample is >0.060 mg/L at any location.

[[Page 492]]

    (b) You are in violation of the MCL when the LRAA exceeds the 
subpart V MCLs in Sec.  141.64(b)(2), calculated based on four 
consecutive quarters of monitoring (or the LRAA calculated based on 
fewer than four quarters of data if the MCL would be exceeded 
regardless of the monitoring results of subsequent quarters). You are 
in violation of the monitoring requirements for each quarter that a 
monitoring result would be used in calculating an LRAA if you fail to 
monitor.
    (c) You may return to routine monitoring once you have conducted 
increased monitoring for at least four consecutive quarters and the 
LRAA for every monitoring location is <=0.060 mg/L for TTHM and <=0.045 
mg/L for HAA5.


Sec.  141.626  Operational evaluation levels.

    (a) You have exceeded the operational evaluation level at any 
monitoring location where the sum of the two previous quarters' TTHM 
results plus twice the current quarter's TTHM result, divided by 4 to 
determine an average, exceeds 0.080 mg/L, or where the sum of the two 
previous quarters' HAA5 results plus twice the current quarter's HAA5 
result, divided by 4 to determine an average, exceeds 0.060 mg/L.
    (b)(1) If you exceed the operational evaluation level, you must 
conduct an operational evaluation and submit a written report of the 
evaluation to the State no later than 90 days after being notified of 
the analytical result that causes you to exceed the operational 
evaluation level. The written report must be made available to the 
public upon request.
    (2) Your operational evaluation must include an examination of 
system treatment and distribution operational practices, including 
storage tank operations, excess storage capacity, distribution system 
flushing, changes in sources or source water quality, and treatment 
changes or problems that may contribute to TTHM and HAA5 formation and 
what steps could be considered to minimize future exceedences.
    (i) You may request and the State may allow you to limit the scope 
of your evaluation if you are able to identify the cause of the 
operational evaluation level exceedance.
    (ii) Your request to limit the scope of the evaluation does not 
extend the schedule in paragraph (b)(1) of this section for submitting 
the written report. The State must approve this limited scope of 
evaluation in writing and you must keep that approval with the 
completed report.


Sec.  141.627  Requirements for remaining on reduced TTHM and HAA5 
monitoring based on subpart L results.

    You may remain on reduced monitoring after the dates identified in 
Sec.  141.620(c) for compliance with this subpart only if you qualify 
for a 40/30 certification under Sec.  141.603 or have received a very 
small system waiver under Sec.  141.604, plus you meet the reduced 
monitoring criteria in Sec.  141.623(a), and you do not change or add 
monitoring locations from those used for compliance monitoring under 
subpart L of this part. If your monitoring locations under this subpart 
differ from your monitoring locations under subpart L of this part, you 
may not remain on reduced monitoring after the dates identified in 
Sec.  141.620(c) for compliance with this subpart.


Sec.  141.628  Requirements for remaining on increased TTHM and HAA5 
monitoring based on subpart L results.

    If you were on increased monitoring under Sec.  141.132(b)(1), you 
must remain on increased monitoring until you qualify for a return to 
routine monitoring under Sec.  141.625(c). You must conduct increased 
monitoring under Sec.  141.625 at the monitoring locations in the 
monitoring plan developed under Sec.  141.622 beginning at the date 
identified in Sec.  141.620(c) for compliance with this subpart and 
remain on increased monitoring until you qualify for a return to 
routine monitoring under Sec.  141.625(c).


Sec.  141.629  Reporting and recordkeeping requirements.

    (a) Reporting. (1) You must report the following information for 
each monitoring location to the State within 10 days of the end of any 
quarter in which monitoring is required:
    (i) Number of samples taken during the last quarter.
    (ii) Date and results of each sample taken during the last quarter.
    (iii) Arithmetic average of quarterly results for the last four 
quarters for each monitoring location (LRAA), beginning at the end of 
the fourth calendar quarter that follows the compliance date and at the 
end of each subsequent quarter. If the LRAA calculated based on fewer 
than four quarters of data would cause the MCL to be exceeded 
regardless of the monitoring results of subsequent quarters, you must 
report this information to the State as part of the first report due 
following the compliance date or anytime thereafter that this 
determination is made. If you are required to conduct monitoring at a 
frequency that is less than quarterly, you must make compliance 
calculations beginning with the first compliance sample taken after the 
compliance date, unless you are required to conduct increased 
monitoring under Sec.  141.625.
    (iv) Whether, based on Sec.  141.64(b)(2) and this subpart, the MCL 
was violated at any monitoring location.
    (v) Any operational evaluation levels that were exceeded during the 
quarter and, if so, the location and date, and the calculated TTHM and 
HAA5 levels.
    (2) If you are a subpart H system seeking to qualify for or remain 
on reduced TTHM/HAA5 monitoring, you must report the following source 
water TOC information for each treatment plant that treats surface 
water or ground water under the direct influence of surface water to 
the State within 10 days of the end of any quarter in which monitoring 
is required:
    (i) The number of source water TOC samples taken each month during 
last quarter.
    (ii) The date and result of each sample taken during last quarter.
    (iii) The quarterly average of monthly samples taken during last 
quarter or the result of the quarterly sample.
    (iv) The running annual average (RAA) of quarterly averages from 
the past four quarters.
    (v) Whether the RAA exceeded 4.0 mg/L.
    (3) The State may choose to perform calculations and determine 
whether the MCL was exceeded or the system is eligible for reduced 
monitoring in lieu of having the system report that information
    (b) Recordkeeping. You must retain any subpart V monitoring plans 
and your subpart V monitoring results as required by Sec.  141.33.

PART 142--NATIONAL PRIMARY DRINKING WATER REGULATIONS 
IMPLEMENTATION

0
21. The authority citation for part 142 continues to read as follows:

    Authority: 42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-
5, 300g-6, 300j-4, 300j-9, and 300j-11.

0
22. Section 142.14 is amended by adding paragraph (a)(8) to read as 
follows:


Sec.  142.14  Records kept by States.

    (a) * * *
    (8) Any decisions made pursuant to the provisions of 40 CFR part 
141, subparts U and V of this part.
    (i) IDSE monitoring plans, plus any modifications required by the 
State, must be kept until replaced by approved IDSE reports.
    (ii) IDSE reports and 40/30 certifications, plus any modifications

[[Page 493]]

required by the State, must be kept until replaced or revised in their 
entirety.
    (iii) Operational evaluations submitted by a system must be kept 
for 10 years following submission.
* * * * *

0
23. Section 142.16 is amended by adding paragraph (m) to read as 
follows:


Sec.  142.16  Special primacy requirements.

* * * * *
    (m) Requirements for States to adopt 40 CFR part 141, subparts U 
and V. In addition to the general primacy requirements elsewhere in 
this part, including the requirements that State regulations be at 
least as stringent as federal requirements, an application for approval 
of a State program revision that adopts 40 CFR part 141, subparts U and 
V, must contain a description of how the State will implement a 
procedure for addressing modification of wholesale system and 
consecutive system monitoring on a case-by-case basis for part 141 
subpart V outside the provisions of Sec.  141.29 of this chapter, if 
the State elects to use such an authority. The procedure must ensure 
that all systems have at least one compliance monitoring location.
* * * * *

[FR Doc. 06-3 Filed 1-3-06; 8:45 am]
BILLING CODE 6560-50-P