[Federal Register Volume 65, Number 97 (Thursday, May 18, 2000)]
[Rules and Regulations]
[Pages 31682-31719]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 00-11106]



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Part III





Environmental Protection Agency





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40 CFR Part 131



Water Quality Standards; Establishment of Numeric Criteria for Priority 
Toxic Pollutants for the State of California; Rule

Federal Register / Vol. 65, No. 97 / Thursday, May 18, 2000 / Rules 
and Regulations

[[Page 31682]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 131

[FRL-6587-9]
RIN 2040-AC44


Water Quality Standards; Establishment of Numeric Criteria for 
Priority Toxic Pollutants for the State of California

AGENCY: Environmental Protection Agency.

ACTION: Final rule.

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SUMMARY: This final rule promulgates: numeric aquatic life criteria for 
23 priority toxic pollutants; numeric human health criteria for 57 
priority toxic pollutants; and a compliance schedule provision which 
authorizes the State to issue schedules of compliance for new or 
revised National Pollutant Discharge Elimination System permit limits 
based on the federal criteria when certain conditions are met.
    EPA is promulgating this rule based on the Administrator's 
determination that numeric criteria are necessary in the State of 
California to protect human health and the environment. The Clean Water 
Act requires States to adopt numeric water quality criteria for 
priority toxic pollutants for which EPA has issued criteria guidance, 
the presence or discharge of which could reasonably be expected to 
interfere with maintaining designated uses.
    EPA is promulgating this rule to fill a gap in California water 
quality standards that was created in 1994 when a State court 
overturned the State's water quality control plans which contained 
water quality criteria for priority toxic pollutants. Thus, the State 
of California has been without numeric water quality criteria for many 
priority toxic pollutants as required by the Clean Water Act, 
necessitating this action by EPA. These Federal criteria are legally 
applicable in the State of California for inland surface waters, 
enclosed bays and estuaries for all purposes and programs under the 
Clean Water Act.

EFFECTIVE DATE: This rule shall be effective May 18, 2000.

ADDRESSES: The administrative record for today's final rule is 
available for public inspection at the U.S. Environmental Protection 
Agency, Region 9, Water Division, 75 Hawthorne Street, San Francisco, 
California 94105, between the hours of 8:00 a.m. and 4:30 p.m. For 
access to the administrative record, call Diane E. Fleck, P.E., Esq. at 
415 744-1984 for an appointment. A reasonable fee will be charged for 
photocopies.

FOR FURTHER INFORMATION CONTACT: Diane E. Fleck, P.E., Esq. or Philip 
Woods, U.S. Environmental Protection Agency, Region 9, Water Division, 
75 Hawthorne Street, San Francisco, California 94105, 415-744-1984 or 
415-744-1997, respectively.

SUPPLEMENTARY INFORMATION: This preamble is organized according to the 
following outline:
A. Potentially Affected Entities
B. Introduction and Overview
1. Introduction
2. Overview
C. Statutory and Regulatory Background
D. California Water Quality Standards Actions
1. California Regional Water Quality Control Board Basin Plans, and 
the Inland Surface Waters Plan (ISWP) and the Enclosed Bays and 
Estuaries Plan (EBEP) of April 1991
2. EPA's Review of California Water Quality Standards for Priority 
Toxic Pollutants in the ISWP and EBEP, and the National Toxics Rule
3. Status of Implementation of CWA Section 303(c)(2)(B)
4. State-Adopted, Site-Specific Criteria for Priority Toxic 
Pollutants
a. State-Adopted Site-Specific Criteria Under EPA Review
b. State-Adopted Site-Specific Criteria With EPA Approval
E. Rationale and Approach For Developing the Final Rule
1. Legal Basis
2. Approach for Developing this Rule
F. Derivation of Criteria
1. Section 304(a) Criteria Guidance Process
2. Aquatic Life Criteria
a. Freshwater Acute Selenium Criterion
b. Dissolved Metals Criteria
c. Application of Metals Criteria
d. Saltwater Copper Criteria
e. Chronic Averaging Period
f. Hardness
3. Human Health Criteria
a. 2,3,7,8-TCDD (Dioxin) Criteria
b. Arsenic Criteria
c. Mercury Criteria
d. Polychlorinated Biphenyls (PCBs) Criteria
e. Excluded Section 304(a) Human Health Criteria
f. Cancer Risk Level
G. Description of Final Rule
1. Scope
2. EPA Criteria for Priority Toxic Pollutants
3. Implementation
4. Wet Weather Flows
5. Schedules of Compliance
6. Changes from Proposed Rule
H. Economic Analysis
1. Costs
2. Benefits
I. Executive Order 12866, Regulatory Planning and Review
J. Unfunded Mandates Reform Act of 1995
K. Regulatory Flexibility Act
L. Paperwork Reduction Act
M. Endangered Species Act
N. Congressional Review Act
O. Executive Order 13084, Consultation and Coordination With Indian 
Tribal Governments
P. National Technology Transfer and Advancement Act
Q. Executive Order 13132 on Federalism
R. Executive Order 13045 on Protection of Children From 
Environmental Health Risks and Safety Risks

A. Potentially Affected Entities

    Citizens concerned with water quality in California may be 
interested in this rulemaking. Entities discharging pollutants to 
waters of the United States in California could be affected by this 
rulemaking since water quality criteria are used by the State in 
developing National Pollutant Discharge Elimination System (NPDES) 
permit limits. Categories and entities that ultimately may be affected 
include:

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           Category            Examples of potentially affected entities
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Industry.....................  Industries discharging pollutants to
                                surface waters in California or to
                                publicly-owned treatment works.
Municipalities...............  Publicly-owned treatment works
                                discharging pollutants to surface waters
                                in California
------------------------------------------------------------------------

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be affected by this 
action. This table lists the types of entities that EPA is now aware 
could potentially be affected by this action. Other types of entities 
not listed in the table could also be affected. To determine whether 
your facility might be affected by this action, you should carefully 
examine the applicability criteria in Sec. 131.38(c). If you have 
questions regarding the applicability of this action to a particular 
entity, consult the persons listed in the preceding FOR FURTHER 
INFORMATION CONTACT section.

[[Page 31683]]

B. Introduction and Overview

1. Introduction

    This section introduces the topics which are addressed in the 
preamble and provides a brief overview of EPA's basis and rationale for 
promulgating Federal criteria for the State of California. Section C 
briefly describes the evolution of the efforts to control toxic 
pollutants; these efforts include the changes enacted in the 1987 CWA 
Amendments, which are the basis for this rule. Section D summarizes 
California's efforts since 1987 to implement the requirements of CWA 
section 303(c)(2)(B) and describes EPA's procedure and actions for 
determining whether California has fully implemented CWA section 
303(c)(2)(B). Section E provides the rationale and approach for 
developing this final rule, including a discussion of EPA's legal basis 
for this final rule. Section F describes the development of the 
criteria included in this rule. Section G summarizes the provisions of 
the final rule and discusses implementation issues. Sections H, I, J, K 
, L, M, N, O, P, and Q briefly address the requirements of Executive 
Order 12866, the Unfunded Mandates Reform Act of 1995, the Regulatory 
Flexibility Act, the Paperwork Reduction Act, the Endangered Species 
Act, the Congressional Review Act, Executive Order 13084, Consultation 
and Coordination with Indian Tribal Governments, the National 
Technology Transfer and Advancement Act, and Executive Order 13132, 
Federalism, respectively.
    The proposal for this rulemaking was published in the Federal 
Register on August 5, 1997. Changes from the proposal are generally 
addressed in the body of this preamble and specifically addressed in 
the response to comments document included in the administrative record 
for this rulemaking. EPA responded to all comments on the proposed 
rule, including comments received after the September 26, 1997, 
deadline. Although EPA is under no legal obligation to respond to late 
comments, EPA made a policy decision to respond to all comments.
    Since detailed information concerning many of the topics in this 
preamble was published previously in the Federal Register in preambles 
for this and other rulemakings, references are frequently made to those 
preambles. Those rulemakings include: Water Quality Standards; 
Establishment of Numeric Criteria for Priority Toxic Pollutants for the 
State of California; Proposed Rule, 62 FR 42159, August 5, 1997 
(referred to as the ``proposed CTR''); Water Quality Standards; 
Establishment of Numeric Criteria for Priority Toxic Pollutants, 57 FR 
60848, December 22, 1992 (referred to as the ``National Toxics Rule'' 
or ``NTR''); and the NTR as amended by Administrative Stay of Federal 
Water Quality Criteria for Metals and Interim Final Rule, Water Quality 
Standards; Establishment of Numeric Criteria for Priority Toxic 
Pollutants; States' Compliance--Revision of Metals Criteria, 60 FR 
22228, May 4, 1995 (referred to as the ``National Toxics Rule [NTR], as 
amended''). The NTR, as amended, is codified at 40 CFR 131.36. A copy 
of the proposed CTR and its preamble, and the NTR, as amended, and its 
preambles are contained in the administrative record for this 
rulemaking.
    EPA is making this final rule effective upon publication. Under the 
Administrative Procedure Act, 5 U.S.C. 553(d)(3), agencies must 
generally publish a rule no more than 30 days prior to the effective 
date of the rule except as otherwise provided for by the Agency for 
good cause. The purpose of the 30-day waiting period is to give 
affected parties a reasonable time to adjust their behavior before the 
final rule takes effect. See Omnipoint Corp. v. F.C.C., 78 F.3d 620, 
630-631 (D.C. Cir. 1996); Riverbend Farms, Inc. v. Madigan, 958 F.2d 
1479, 1485 (9th Cir. 1992).
    In this instance, EPA finds good cause to make the final rule 
effective upon publication. In order to find good cause, an Agency 
needs to find that the 30-day period would be: (1) Impracticable, (2) 
unnecessary, or (3) contrary to the public interest. Here EPA is 
relying on the second reason to support its finding of good cause. EPA 
also notes that the State has requested EPA to make the rule 
immediately effective.
    EPA finds that in this instance, waiting 30 days to make the rule 
effective is unnecessary. As explained in further detail elsewhere in 
this preamble, this rule is not self implementing; rather it 
establishes ambient conditions that the State of California will 
implement in future permit proceedings. These permit proceedings will, 
by regulation, take longer than 30 days to complete. This means that 
although the rule is immediately effective, no discharger's conduct 
would be altered under the rule in less than 30 days, and therefore the 
30-day period is unnecessary.

2. Overview

    This final rule establishes ambient water quality criteria for 
priority toxic pollutants in the State of California. The criteria in 
this final rule will supplement the water quality criteria promulgated 
for California in the NTR, as amended. In 1991, EPA approved a number 
of water quality criteria (discussed in section D), for the State of 
California. Since EPA had approved these criteria, it was not necessary 
to include them in the 1992 NTR for these criteria. However, the EPA-
approved criteria were subsequently invalidated in State litigation. 
Thus, this final rule contains criteria to fill the gap created by the 
State litigation.
    This final rule does not change or supersede any criteria 
previously promulgated for the State of California in the NTR, as 
amended. Criteria which EPA promulgated for California in the NTR, as 
amended, are footnoted in the final table at 131.38(b)(1), so that 
readers may see the criteria promulgated in the NTR, as amended, for 
California and the criteria promulgated through this rulemaking for 
California in the same table. This final rule is not intended to apply 
to waters within Indian Country. EPA recognizes that there are possibly 
waters located wholly or partly in Indian Country that are included in 
the State's basin plans. EPA will work with the State and Tribes to 
identify any such waters and determine whether further action to 
protect water quality in Indian Country is necessary.
    This rule is important for several environmental, programmatic and 
legal reasons. Control of toxic pollutants in surface waters is 
necessary to achieve the CWA's goals and objectives. Many of 
California's monitored river miles, lake acres, and estuarine waters 
have elevated levels of toxic pollutants. Recent studies on California 
water bodies indicate that elevated levels of toxic pollutants exist in 
fish tissue which result in fishing advisories or bans. These toxic 
pollutants can be attributed to, among other sources, industrial and 
municipal discharges.
    Water quality standards for toxic pollutants are important to State 
and EPA efforts to address water quality problems. Clearly established 
water quality goals enhance the effectiveness of many of the State's 
and EPA's water programs including permitting, coastal water quality 
improvement, fish tissue quality protection, nonpoint source controls, 
drinking water quality protection, and ecological protection. Numeric 
criteria for toxic pollutants allow the State and EPA to evaluate the 
adequacy of existing and potential control measures to protect aquatic 
ecosystems and human health. Numeric criteria also provide a more 
precise basis for deriving water quality-based effluent limitations 
(WQBELs) in

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National Pollutant Discharge Elimination System (NPDES) permits and 
wasteload allocations for total maximum daily loads (TMDLs) to control 
toxic pollutant discharges. Congress recognized these issues when it 
enacted section 303(c)(2)(B) to the CWA.
    While California recognizes the need for applicable water quality 
standards for toxic pollutants, its adoption efforts have been stymied 
by a variety of factors. The Administrator has decided to exercise her 
CWA authorities to move forward the toxic control program, consistent 
with the CWA and with the State of California's water quality standards 
program.
    Today's action will also help restore equity among the States. The 
CWA is designed to ensure all waters are sufficiently clean to protect 
public health and/or the environment. The CWA allows some flexibility 
and differences among States in their adopted and approved water 
quality standards, but it should be implemented in a manner that 
ensures a level playing field among States. Although California has 
made important progress toward satisfying CWA requirements, it has not 
satisfied CWA section 303(c)(2)(B) by adopting numeric water quality 
criteria for toxic pollutants. This section was added to the CWA by 
Congress in 1987. Prior to today, the State of California had been the 
only State in the Nation for which CWA section 303(c)(2)(B) had 
remained substantially unimplemented after EPA's promulgation of the 
NTR in December of 1992. Section 303(c)(4) of the CWA authorizes the 
EPA Administrator to promulgate standards where necessary to meet the 
requirements of the Act. The Administrator determined that this rule 
was a necessary and important component for the implementation of CWA 
section 303(c)(2)(B) in California.
    EPA acknowledges that the State of California is working to satisfy 
CWA section 303(c)(2)(B). When the State formally adopts, and EPA 
approves, criteria consistent with statutory requirements, as 
envisioned by Congress in the CWA, EPA intends to stay this rule. If 
within the applicable time frame for judicial review, the States' 
standards are challenged, EPA will withdraw this rule after such 
judicial review is complete and the State standards are sustained.

C. Statutory and Regulatory Background

    The preamble to the August 5, 1997, proposed rule provided a 
general discussion of EPA's statutory and regulatory authority to 
promulgate water quality criteria for the State of California. See 62 
FR 42160-42163. EPA is including that discussion in the record for the 
final rule. Commenters questioned EPA's authority to promulgate certain 
aspects of the proposal. EPA is responding to those comments in the 
appropriate sections of this preamble, and in the response to comments 
document included in the administrative record for this rulemaking. 
Where appropriate, EPA's responses expand upon the discussion of 
statutory and regulatory authority found in the proposal.

D. California Water Quality Standards Actions

1. California Regional Water Quality Control Board Basin Plans, and the 
Inland Surface Waters Plan (ISWP) and the Enclosed Bays and Estuaries 
Plan (EBEP) of April 1991

    The State of California regulates water quality through its State 
Water Resources Control Board (SWRCB) and through nine Regional Water 
Quality Control Boards (RWQCBs). Each of the nine RWQCBs represents a 
different geographic area; area boundaries are generally along 
watershed boundaries. Each RWQCB maintains a Basin Plan which contains 
the designated uses of the water bodies within its respective 
geographic area within California. These designated uses (or 
``beneficial uses'' under State law) together with legally-adopted 
criteria (or ``objectives'' under State law), comprise water quality 
standards for the water bodies within each of the Basin areas. Each of 
the nine RWQCBs undergoes a triennial basin planning review process, in 
compliance with CWA section 303. The SWRCB provides assistance to the 
RWQCBs.
    Most of the Basin Plans contain conventional pollutant objectives 
such as dissolved oxygen. None of the Basin Plans contains a 
comprehensive list of priority toxic pollutant criteria to satisfy CWA 
section 303(c)(2)(B). The nine RWQCBs and the SWRCB had intended that 
the priority toxic pollutant criteria contained in the three SWRCB 
statewide plans, the Inland Surface Waters Plan (ISWP), the Enclosed 
Bays and Estuaries Plan (EBEP), and the Ocean Plan, apply to all basins 
and satisfy CWA section 303(c)(2)(B).
    On April 11, 1991, the SWRCB adopted two statewide water quality 
control plans, the ISWP and the EBEP. These statewide plans contained 
narrative and numeric water quality criteria for toxic pollutants, in 
part to satisfy CWA section 303(c)(2)(B). The water quality criteria 
contained in the SWRCB statewide plans, together with the designated 
uses in each of the Basin Plans, created a set of water quality 
standards for waters within the State of California.
    Specifically, the two plans established water quality criteria or 
objectives for all fresh waters, bays and estuaries in the State. The 
plans contained water quality criteria for some priority toxic 
pollutants, provisions relating to whole effluent toxicity, 
implementation procedures for point and nonpoint sources, and 
authorizing compliance schedule provisions. The plans also included 
special provisions affecting waters dominated by reclaimed water 
(labeled as Category (a) waters), and waters dominated by agricultural 
drainage and constructed agricultural drains (labeled as Category (b) 
and (c) waters, respectively).

2. EPA's Review of California Water Quality Standards for Priority 
Toxic Pollutants in the ISWP and EBEP, and the National Toxics Rule

    The EPA Administrator has delegated the responsibility and 
authority for review and approval or disapproval of all new or revised 
State water quality standards to the EPA Regional Administrators (see 
40 CFR 131.21). Thus, State actions under CWA section 303(c)(2)(B) are 
submitted to the appropriate EPA Regional Administrator for review and 
approval.
    In mid-April 1991, the SWRCB submitted to EPA for review and 
approval the two statewide water quality control plans, the ISWP and 
the EBEP. On November 6, 1991, EPA Region 9 formally concluded its 
review of the SWRCB's plans. EPA approved the narrative water quality 
criterion and the toxicity criterion in each of the plans. EPA also 
approved the numeric water quality criteria contained in both plans, 
finding them to be consistent with the requirements of section 
303(c)(2)(B) of the CWA and with EPA's national criteria guidance 
published pursuant to section 304(a) of the CWA.
    EPA noted the lack of criteria for some pollutants, and found that, 
because of the omissions, the plans did not fully satisfy CWA section 
303(c)(2)(B). The plans did not contain criteria for all listed 
pollutants for which EPA had published national criteria guidance. The 
ISWP contained human health criteria for only 65 pollutants, and the 
EBEP contained human health criteria for only 61 pollutants for which 
EPA had issued section 304(a) guidance criteria. Both the ISWP and EBEP 
contained aquatic life criteria for all pollutants except cyanide and 
chromium III (freshwater only) for which EPA has CWA section

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304(a) criteria guidance. The SWRCB's administrative record stated that 
all priority pollutants with EPA criteria guidance were likely to be 
present in California waters. However, the SWRCB's record contained 
insufficient information to support a finding that the excluded 
pollutants were not reasonably expected to interfere with designated 
uses of the waters of the State.
    Although EPA approved the statewide selenium objective in the ISWP 
and EBEP, EPA disapproved the objective for the San Francisco Bay and 
Delta, because there was clear evidence that the objective would not 
protect the designated fish and wildlife uses (the California 
Department of Health Services had issued waterfowl consumption 
advisories due to selenium concentrations, and scientific studies had 
documented selenium toxicity to fish and wildlife). EPA restated its 
commitment to object to National Pollutant Discharge Elimination System 
(NPDES) permits issued for San Francisco Bay that contained effluent 
limits based on an objective greater than 5 parts per billion (ppb) 
(four day average) and 20 ppb (1 hour average), the freshwater 
criteria. EPA reaffirmed its disapproval of Californias' site-specific 
selenium objective for portions of the San Joaquin River, Salt Slough, 
and Mud Slough. EPA also disapproved of the categorical deferrals and 
exemptions. These disapprovals included the disapproval of the State's 
deferral of water quality objectives to effluent dominated streams 
(Category a) and to streams dominated by agricultural drainage 
(Category b), and the disapproval of the exemption of water quality 
objectives to constructed agricultural drains (Category c). EPA found 
the definitions of the categories imprecise and overly broad which 
could have led to an incorrect interpretation.
    Since EPA had disapproved portions of each of the California 
statewide plans which were necessary to satisfy CWA section 
303(c)(2)(B), certain disapproved aspects of California's water quality 
standards were included in EPA's promulgation of the National Toxics 
Rule (NTR) (40 CFR 131.36, 57 FR 60848). EPA promulgated specific 
criteria for certain water bodies in California.
    The NTR was amended, effective April 14, 1995, to stay certain 
metals criteria which had been promulgated as total recoverable. 
Effective April 15, 1995, EPA promulgated interim final metals criteria 
as dissolved concentrations for those metals which had been stayed 
(Administrative Stay of Federal Water Quality Criteria for Metals and 
Interim Final Rule, Water Quality Standards; Establishment of Numeric 
Criteria for Priority Toxic Pollutants; States' Compliance--Revision of 
Metals Criteria; 60 FR 22228, 22229, May 4, 1995 [the NTR, as 
amended]). The stay was in response to a lawsuit against EPA 
challenging, among other issues, metals criteria expressed as total 
recoverable concentrations. A partial Settlement Agreement required EPA 
to stay specific metals criteria in the NTR. EPA then promulgated 
certain metals criteria in the dissolved form through the use of 
conversion factors. These factors are listed in the NTR, as amended. A 
scientific discussion of these criteria is found in a subsequent 
section of this preamble.
    Since certain criteria have already been promulgated for specific 
water bodies in the State of California in the NTR, as amended, they 
are not within the scope of today's final rule. However, for clarity in 
reading a comprehensive rule for the State of California, these 
criteria are incorporated into 40 CFR 131.38(d)(2). Footnotes to the 
Table in 40 CFR 131.38(b)(1) and 40 CFR 131.38(d)(3) clarify which 
criteria (and for which specific water bodies) were promulgated by the 
NTR, as amended, and are therefore excluded from this final rule. The 
appropriate (freshwater or saltwater) aquatic life criteria which were 
promulgated in the NTR, as amended, for all inland surface waters and 
enclosed bays and estuaries include: chromium III and cyanide. The 
appropriate (water and organism or organism only) human health criteria 
which were promulgated in the NTR, as amended, for all inland surface 
waters and enclosed bays and estuaries include:

antimony
thallium
asbestos
acrolein
acrylonitrile
carbon tetrachloride
chlorobenzene
1,2-dichloroethane
1,1-dichloroethylene
1,3-dichloropropylene
ethylbenzene
1,1,2,2-tetrachloroethane
tetrachloroethylene
1,1,2-trichloroethane
trichloroethylene
vinyl chloride
2,4-dichlorophenol
2-methyl-4,6-dinitrophenol
2,4-dinitrophenol
benzidine
bis(2-chloroethyl)ether
bis(2-ethylhexyl)phthalate
3,3-dichlorobenzidine
diethyl phthalate
dimethyl phthalate
di-n-butyl phthalate
2,4-dinitrotoluene
1,2-diphenylhydrazine
hexachlorobutadiene
hexachlorocyclopentadiene
hexachloroethane
isophorone
nitrobenzene
n-nitrosodimethylamine
n-nitrosodiphenylamine

    Other pollutant criteria were promulgated in the NTR, as amended, 
for specific water bodies, but not all inland surface waters and 
enclosed bays and estuaries.

3. Status of Implementation of CWA Section 303(c)(2)(B)

    Shortly after the SWRCB adopted the ISWP and EBEP, several 
dischargers filed suit against the State alleging that it had not 
adopted the two plans in compliance with State law. The plaintiffs in a 
consolidated case included: the County of Sacramento, Sacramento County 
Water Agency; Sacramento Regional County Sanitation District; the City 
of Sacramento; the City of Sunnyvale; the City of San Jose; the City of 
Stockton; and Simpson Paper Company.
    The dischargers alleged that the State had not adopted the ISWP and 
EBEP in compliance with the California Administrative Procedures Act 
(Gov Code. Section 11340, et seq.), the California Environmental 
Quality Act (Pub. Re Code, Section 21000, et seq.), and the Porter-
Cologne Act (Wat. Code, Section 13200, et seq.). The allegation that 
the State did not sufficiently consider economics when adopting water 
quality objectives, as allegedly required by Section 13241 of the 
Porter Cologne Act, was an important issue in the litigation.
    In October of 1993, the Superior Court of California, County of 
Sacramento, issued a tentative decision in favor of the dischargers. In 
March of 1994, the Court issued a substantively similar final decision 
in favor of the dischargers. Final judgments from the Court in July of 
1994 ordered the SWRCB to rescind the ISWP and EBEP. On September 22, 
1994, the SWRCB formally rescinded the two statewide water quality 
control plans. The State is currently in the process of readopting 
water quality control plans for inland surface waters, enclosed bays 
and estuaries.
    CWA section 303(c)(2)(B) was fully implemented in the State of 
California from December of 1992, when the NTR was promulgated, until 
September of 1994, when the SWRCB was required to rescind the ISWP and 
EBEP. The provisions for California in EPA's NTR together with the 
approved portions of

[[Page 31686]]

California's ISWP and EBEP implemented the requirements of CWA section 
303(c)(2)(B). However, since September of 1994, when the SWRCB 
rescinded the ISWP and EBEP, the requirements of section 303(c)(2)(B) 
have not been fully implemented in California.
    The scope of today's rule is to re-establish criteria for the 
remaining priority toxic pollutants to meet the requirements of section 
303(c)(2)(B) of the CWA. Pursuant to section 303(c)(4), the 
Administrator has determined that it is necessary to include in today's 
action criteria for priority toxic pollutants, which are not covered by 
the NTR, as amended, or by the State through EPA-approved site-specific 
criteria, for waters of the United States in the State of California.

4. State-Adopted, Site-Specific Criteria for Priority Toxic Pollutants

    The State has the discretion to develop site-specific criteria when 
appropriate e.g., when statewide criteria appear over-or under-
protective of designated uses. Periodically, the State through its 
RWQCBs will adopt site-specific criteria for priority toxic pollutants 
within respective Basin Plans. These criteria are intended to be 
effective throughout the Basin or throughout a designated water body. 
Under California law, these criteria must be publicly reviewed and 
approved by the RWQCB, the SWRCB, and the State's Office of 
Administrative Law (OAL). Once this adoption process is complete, the 
criteria become State law.
    These criteria must be submitted to the EPA Regional Administrator 
for review and approval under CWA section 303. These criteria are 
usually submitted to EPA as part of a RWQCB Basin Plan Amendment, after 
the Amendment has been adopted under the State's process and has become 
State law.
a. State-Adopted Site-Specific Criteria Under EPA Review
    The State of California has recently reviewed and updated all of 
its RWQCB Basin Plans. All of the Basin Plans have completed the State 
review and adoption process and have been submitted to EPA for review 
and approval. Some of the Basin Plans contain site-specific criteria. 
In these cases, the State-adopted site-specific criteria are used for 
water quality programs.
    EPA has not yet concluded consultation under the Endangered Species 
Act with the U.S. Department of Interior, Fish and Wildlife Service, 
and the U.S. Department of Commerce, National Marine Fisheries Service, 
on EPA's tentative approval/disapproval actions on the RWQCB Basin 
Plans. In this situation, the more stringent of the two criteria (the 
State-adopted site-specific criteria in the RWQCB Basin Plans, or the 
Federal criteria in this final rule), would be used for water quality 
programs including the calculation of water quality-based effluent 
criteria in National Pollutant Discharge Elimination System (NPDES) 
permits.
b. State-Adopted Site-Specific Criteria With EPA Approval
    In several cases, the EPA Regional Administrator has already 
reviewed and approved State-adopted site-specific criteria within the 
State of California. Several of these cases are discussed in this 
section. All of the EPA approval letters referenced in today's preamble 
are contained in the administrative record for today's rule.
    Sacramento River: EPA has approved site-specific acute criteria for 
copper, cadmium and zinc in the Sacramento River, upstream of Hamilton 
City, in the Central Valley Region (RWQCB for the Central Valley 
Region) of the State of California. EPA approved these site-specific 
criteria by letter dated August 7, 1985. Specifically, EPA approved for 
the Sacramento River (and tributaries) above Hamilton City, a copper 
criterion of 5.6 g/l (maximum), a zinc criterion of 16 
g/l (maximum) and a cadmium criterion of 0.22 g/l 
(maximum), all in the dissolved form using a hardness of 40 mg/l as 
CaCO3. (These criteria were actually adopted by the State and approved 
by EPA as equations which vary with hardness.) These ``maximum'' 
criteria correspond to acute criteria in today's final rule. Therefore, 
Federal acute criteria for copper, cadmium, and zinc for the Sacramento 
River (and tributaries) above Hamilton City are not necessary to 
protect the designated uses and are not included in the final rule. 
However, the EPA Administrator is making a finding that it is necessary 
to include chronic criteria for copper, cadmium and zinc for the 
Sacramento River (and tributaries) above Hamilton City, as part of the 
statewide criteria promulgated in today's final rule.
    San Joaquin River: The selenium criteria in this rule are not 
applicable to portions of the San Joaquin River, in the Central Valley 
Region, because selenium criteria have been either previously approved 
by EPA or previously promulgated by EPA as part of the NTR. EPA 
approved and disapproved State-adopted site-specific selenium criteria 
in portions of the San Joaquin River, in the Central Valley Region of 
the State of California (RWQCB for the Central Valley Region). EPA's 
determination on these site-specific criteria is contained in a letter 
dated April 13, 1990.
    Specifically, EPA approved for the San Joaquin River, mouth of 
Merced River to Vernalis, an aquatic life selenium criterion of 12 
g/l (maximum with the understanding that the instantaneous 
maximum concentration may not exceed the objective more than once every 
three years). Today's final rule does not affect this Federally-
approved, State-adopted site-specific acute criterion, and it remains 
in effect for the San Joaquin River, mouth of Merced River to Vernalis. 
Therefore, an acute criterion for selenium in the San Joaquin River, 
mouth of Merced River to Vernalis is not necessary to protect the 
designated use and thus is not included in this final rule.
    By letter dated April 13, 1990, EPA also approved for the San 
Joaquin River, mouth of Merced River to Vernalis, a State-adopted site-
specific aquatic life selenium criterion of 5 g/l (monthly 
mean); however, EPA disapproved a State-adopted site-specific selenium 
criterion of 8 g/l (monthly mean--critical year only) for 
these waters. Subsequently, EPA promulgated a chronic selenium 
criterion of 5 g/l (4 day average) for waters of the San 
Joaquin River from the mouth of the Merced River to Vernalis in the 
NTR. This chronic criterion applies to all water quality programs 
concerning the San Joaquin River, mouth of Merced River to Vernalis. 
Today's final rule does not affect the Federally-promulgated chronic 
selenium criterion of 5 g/l (4 day average) set forth in the 
NTR. This previously Federally-promulgated criterion remains in effect 
for the San Joaquin River, mouth of Merced River to Vernalis.
    Grassland Water District, San Luis National Wildlife Refuge, and 
Los Banos State Wildlife Refuge: EPA approved for the Grassland Water 
District, San Luis National Wildlife Refuge, and Los Banos State 
Wildlife Refuge, a State-adopted site-specific aquatic life selenium 
criterion of 2 g/l (monthly mean) by letter dated April 13, 
1990. This Federally-approved, State-adopted site-specific chronic 
criterion remains in effect for the Grassland Water District, San Luis 
National Wildlife Refuge and Los Banos State Wildlife Refuge. Therefore 
it is not necessary to include in today's final rule, a chronic 
criterion for selenium for the Grassland Water District, San Luis 
National Wildlife Refuge and Los Banos State Wildlife Refuge, and thus, 
it is not included in this final rule.

[[Page 31687]]

    San Francisco Regional Board Basin Plan of 1986: EPA approved 
several priority toxic pollutant objectives (CWA criteria) that were 
contained in the1986 San Francisco Regional Board Basin Plan, as 
amended by SWRCB Resolution Numbers 87-49, 87-82 and 87-92, by letters 
dated September 2, 1987 and December 24, 1987. This Basin Plan, the 
SWRCB Resolutions, and the EPA approval letters are contained in the 
administrative record for this rulemaking. It is not necessary to 
include these criteria for priority toxic pollutants that are contained 
in the San Francisco Regional Board's 1986 Basin Plan as amended, and 
approved by EPA. Priority pollutants in this situation are footnoted in 
the matrix at 131.38(b)(1) with footnote ``b.'' Where gaps exist in the 
State adoption and EPA approval of priority toxic pollutant objectives, 
the criteria in today's rule apply.
    EPA is assigning ``human health, water and organism consumption'' 
criteria to waters with the States' municipal or ``MUN'' beneficial use 
designation in the Basin Plan. Also, some pollutants regulated through 
the Basin Plan have different averaging periods, e.g., one hour as 
compared with the rule's ``short-term.'' However, where classes of 
chemicals, such as polynuclear aromatic hydrocarbons, or PAHs, and 
phenols, are regulated through the Basin Plan, but not specific 
chemicals within the category, specific chemicals within the category 
are regulated by today's rule.

E. Rationale and Approach for Developing the Final Rule

    This section explains EPA's legal basis for today's final rule, and 
discusses EPA's general approach for developing the specific 
requirements for the State of California.

1. Legal Basis

    CWA section 303(c) specifies that adoption of water quality 
standards is primarily the responsibility of the States. However, CWA 
section 303(c) also describes a role for the Federal government to 
oversee State actions to ensure compliance with CWA requirements. If 
EPA's review of the States' standards finds flaws or omissions, then 
the CWA authorizes EPA to correct the deficiencies (see CWA section 
303(c)(4)). This water quality standards promulgation authority has 
been used by EPA to issue final rules on several separate occasions, 
including the NTR, as amended, which promulgated criteria similar to 
those included here for a number of States. These actions have 
addressed both insufficiently protective State criteria and/or 
designated uses and failure to adopt needed criteria. Thus, today's 
action is not unique.
    The CWA in section 303(c)(4) provides two bases for promulgation of 
Federal water quality standards. The first basis, in paragraph (A), 
applies when a State submits new or revised standards that EPA 
determines are not consistent with the applicable requirements of the 
CWA. If, after EPA's disapproval, the State does not amend its rules so 
as to be consistent with the CWA, EPA is to promptly propose 
appropriate Federal water quality standards for that State. The second 
basis for an EPA action is in paragraph (B), which provides that EPA 
shall promptly initiate promulgation ``* * * in any case where the 
Administrator determines that a revised or new standard is necessary to 
meet the requirements of this Act.'' EPA is using section 303(c)(4)(B) 
as the legal basis for today's final rule.
    As discussed in the preamble to the NTR, the Administrator's 
determination under CWA section 303(c)(4) that criteria are necessary 
to meet the requirements of the Act could be supported in several ways. 
Consistent with EPA's approach in the NTR, EPA interprets section 
303(c)(2)(B) of the CWA to allow EPA to act where the State has not 
succeeded in establishing numeric water quality standards for toxic 
pollutants. This inaction can be the basis for the Administrator's 
determination under section 303(c)(4) that new or revised criteria are 
necessary to ensure designated uses are protected.
    EPA does not believe that it is necessary to support the criteria 
in today's rule on a pollutant-specific, water body-by-water-body 
basis. For EPA to undertake an effort to conduct research and studies 
of each stream segment or water body across the State of California to 
demonstrate that for each toxic pollutant for which EPA has issued CWA 
section 304(a) criteria guidance there is a ``discharge or presence'' 
of that pollutant which could reasonably ``be expected to interfere 
with'' the designated use would impose an enormous administrative 
burden and would be contrary to the statutory directive for swift 
action manifested by the 1987 addition of section 303(c)(2)(B) to the 
CWA. Moreover, because these criteria are ambient criteria that define 
attainment of the designated uses, their application to all water 
bodies will result in additional controls on dischargers only where 
necessary to protect the designated uses.
    EPA's interpretation of section 303(c)(2)(B) is supported by the 
language of the provision, the statutory framework and purpose of 
section 303, and the legislative history. In adding section 
303(c)(2)(B) to the CWA, Congress understood the existing requirements 
in section 303(c)(1) for States to conduct triennial reviews of their 
water quality standards and submit the results of those reviews to EPA 
and in section 303(c)(4)(B) for promulgation. CWA section 303(c) 
includes numerous deadlines and section 303(c)(4) directs the 
Administrator to act ``promptly'' where the Administrator determines 
that a revised or new standard is necessary to meet the requirements of 
the Act. Congress, by linking section 303(c)(2)(B) to the section 
303(c)(1) three-year review period, gave States a last chance to 
correct this deficiency on their own. The legislative history of the 
provision demonstrates that chief Senate sponsors, including Senators 
Stafford, Chaffee and others wanted the provision to eliminate State 
and EPA delays and force quick action. Thus, to interpret CWA section 
303(c)(2)(B) and (c)(4) to require such a cumbersome pollutant specific 
effort on each stream segment would essentially render section 
303(c)(2)(B) meaningless. The provision and its legislative background 
indicate that the Administrator's determination to invoke section 
303(c)(4)(B) authority can be met by the Administrator making a generic 
finding of inaction by the State without the need to develop pollutant 
specific data for individual stream segments. Finally, the reference in 
section 303(c)(2)(B) to section 304(a) criteria suggests that section 
304(a) criteria serve as default criteria; that once EPA has issued 
them, States were to adopt numeric criteria for those pollutants based 
on the 304(a) criteria, unless they had other scientifically defensible 
criteria. EPA also notes that this rule follows the approach EPA took 
nationally in promulgating the NTR for States that failed to comply 
with CWA section 303(c)(2)(B). 57 FR 60848, December 22, 1992. EPA 
incorporates the discussion in the NTR preamble as part of this 
rulemaking record.
    This determination is supported by information in the rulemaking 
record showing the discharge or presence of priority toxic pollutants 
throughout the State. While this data is not necessarily complete, it 
constitutes a strong record supporting the need for numeric criteria 
for priority toxic pollutants with section 304(a) criteria guidance 
where the State does not have numeric criteria.
    Today's final rule would not impose any undue or inappropriate 
burden on the State of California or its dischargers. It merely puts in 
place numeric criteria

[[Page 31688]]

for toxic pollutants that are already used in other States in 
implementing CWA programs. Under this rulemaking, the State of 
California retains the ability to adopt alternative water quality 
criteria simply by completing its criteria adoption process. Upon EPA 
approval of those criteria, EPA will initiate action to stay the 
Federally-promulgated criteria and subsequently withdraw them.

2. Approach for Developing This Rule

    In summary, EPA developed the criteria promulgated in today's final 
rule as follows. Where EPA promulgated criteria for California in the 
NTR, EPA has not acted to amend the criteria in the NTR. Where criteria 
for California were not included in the NTR, EPA used section 304(a) 
National criteria guidance documents as a starting point for the 
criteria promulgated in this rule. EPA then determined whether new 
information since the development of the national criteria guidance 
documents warranted any changes. New information came primarily from 
two sources. For human health criteria, new or revised risk reference 
doses and cancer potency factors on EPA's Integrated Risk Information 
System (IRIS) as of October 1996 form the basis for criteria values 
(see also 63 FR 68354). For aquatic life criteria, updated data sets 
resulting in revised criteria maximum concentrations (CMCs) and 
criteria continuous concentrations (CCCs) formed the basis for 
differences from the national criteria guidance documents. Both of 
these types of changes are discussed in more detail in the following 
sections. This revised information was used to develop the water 
quality criteria promulgated here for the State of California.

F. Derivation of Criteria

1. Section 304(a) Criteria Guidance Process

    Under CWA section 304(a), EPA has developed methodologies and 
specific criteria guidance to protect aquatic life and human health. 
These methodologies are intended to provide protection for all surface 
waters on a national basis. The methodologies have been subject to 
public review, as have the individual criteria guidance documents. 
Additionally, the methodologies have been reviewed by EPA's Science 
Advisory Board (SAB) of external experts.
    EPA has included in the record of this rule the aquatic life 
methodology as described in ``Appendix B--Guidelines for Deriving Water 
Quality Criteria for the Protection of Aquatic Life and Its Uses'' to 
the ``Water Quality Criteria Documents; Availability'' (45 FR 79341, 
November 28, 1980) as amended by the ``Summary of Revisions to 
Guidelines for Deriving Numerical National Water Quality Criteria for 
the Protection of Aquatic Organisms and Their Uses'' (50 FR 30792, July 
29, 1985). (Note: Throughout the remainder of this preamble, this 
reference is described as the 1985 Guidelines. Any page number 
references are to the actual guidance document, not the notice of 
availability in the Federal Register. A copy of the 1985 Guidelines is 
available through the National Technical Information Service (PB85-
227049), is in the administrative record for this rule, and is 
abstracted in Appendix A of Quality Criteria for Water, 1986.) EPA has 
also included in the administrative record of this rule the human 
health methodology as described in ``Appendix C--Guidelines and 
Methodology Used in the Preparation of Health Effects Assessment 
Chapters of the Consent Decree Water Criteria Documents'' (45 FR 79347, 
November 28, 1980). (Note: Throughout the remainder of this preamble, 
this reference is described as the Human Health Guidelines or the 1980 
Guidelines.) EPA also recommends that the following be reviewed: 
``Appendix D--Response to Comments on Guidelines for Deriving Water 
Quality Criteria for the Protection of Aquatic Life and Its Uses,'' (45 
FR 79357, November 28, 1980); ``Appendix E--Responses to Public 
Comments on the Human Health Effects Methodology for Deriving Ambient 
Water Quality Criteria'' (45 FR 79368, November 28, 1980); and 
``Appendix B--Response to Comments on Guidelines for Deriving Numerical 
National Water Quality Criteria for the Protection of Aquatic Organisms 
and Their Uses'' (50 FR 30793, July 29, 1985). EPA placed into the 
administrative record for this rulemaking the most current individual 
criteria guidance for the priority toxic pollutants included in today's 
rule. (Note: All references to appendices are to the associated Federal 
Register publication.)
    EPA received many comments related to the issue of what criteria 
should apply in the CTR if the CWA section 304(a) criteria guidance is 
undergoing re-evaluation, or if new data are developed that may affect 
a recommended criterion. As science is always evolving, EPA is faced 
with the challenge of promulgating criteria that reflect the best 
science and sound science. EPA addressed this challenge in some detail 
in its Federal Register notice that contained the Agency's current 
section 304(a) criteria guidance (63 FR 68335, December 10, 1998). 
There, EPA articulated its policy, reiterated here, that the existing 
criteria guidance represent the Agency's best assessment until such 
time as EPA's re-evaluation of a criteria guidance value for a 
particular chemical is complete. The reason for this is that both EPA's 
human health criteria guidance and aquatic life criteria guidance are 
developed taking into account numerous variables. For example, for 
human health criteria guidance, EPA evaluates many diverse toxicity 
studies, whose results feed into a reference dose or cancer potency 
estimate that, along with a number of exposure factors and 
determination of risk level, results in a guidance criterion. For 
aquatic life, EPA evaluates many diverse aquatic toxicity studies to 
determine chronic and acute toxicity taking into account how other 
factors (such as pH, temperature or hardness) affect toxicity. EPA 
also, to the extent possible, addresses bioaccumulation or 
bioconcentration. EPA then uses this toxicity information along with 
exposure information to determine the guidance criterion. Importantly, 
EPA subjects such evaluation to peer review and/or public comment.
    For these reasons, EPA generally does not make a change to the 
304(a) criteria guidance based on a partial picture of the evolving 
science. This makes sense, because to address one piece of new data 
without looking at all relevant data is less efficient and results in 
regulatory impacts that may go back and forth, when in the end, the 
criteria guidance value does not change that much. Certain new changes, 
however, do warrant change in criteria guidance, such as a change in a 
value in EPA's Integrated Risk Information System (IRIS) because it 
represents the Agency consensus about human health impacts. These 
changes are sufficiently examined across the Agency such that EPA 
believes they can be incorporated into EPA's water quality criteria 
guidance. EPA has followed this approach in the CTR. Included in the 
administrative record for today's rule is a document entitled ``Status 
of Clean Water Act Section 304(a) Criteria'' which further explains 
EPA's policy on managing change to criteria guidance.

2. Aquatic Life Criteria

    Aquatic life criteria may be expressed in numeric or narrative 
form. EPA's 1985 Guidelines describe an objective, internally 
consistent and appropriate way of deriving chemical-specific, numeric 
water quality criteria for the protection of the presence of, as well 
as

[[Page 31689]]

the uses of, both fresh and salt water aquatic organisms.
    An aquatic life criterion derived using EPA's CWA section 304(a) 
method ``might be thought of as an estimate of the highest 
concentration of a substance in water which does not present a 
significant risk to the aquatic organisms in the water and their 
uses.'' (45 FR 79341.) EPA's guidelines are designed to derive criteria 
that protect aquatic communities. EPA's 1985 Guidelines attempt to 
provide a reasonable and adequate amount of protection with only a 
small possibility of substantial overprotection or underprotection. As 
discussed in detail below, there are several individual factors which 
may make the criteria somewhat overprotective or underprotective. The 
approach EPA is using is believed to be as well balanced as possible, 
given the state of the science.
    Numerical aquatic life criteria derived using EPA's 1985 Guidelines 
are expressed as short-term and long-term averages, rather than one 
number, in order that the criterion more accurately reflect 
toxicological and practical realities. The combination of a criterion 
maximum concentration (CMC), a short-term concentration limit, and a 
criterion continuous concentration (CCC), a four-day average 
concentration limit, are designed to provide protection of aquatic life 
and its uses from acute and chronic toxicity to animals and plants, 
without being as restrictive as a one-number criterion would have to be 
(1985 Guidelines, pages 4 & 5). The terms CMC and CCC are the formal 
names for the two (acute and chronic) values of a criterion for a 
pollutant; however, this document will also use the informal synonyms 
acute criterion and chronic criterion.
    The two-number criteria are intended to identify average pollutant 
concentrations which will produce water quality generally suited to 
maintenance of aquatic life and designated uses while restricting the 
duration of excursions over the average so that total exposures will 
not cause unacceptable adverse effects. Merely specifying an average 
value over a time period may be insufficient unless the time period is 
short, because excursions higher than the average may kill or cause 
substantial damage in short periods.
    A minimum data set of eight specified families is recommended for 
criteria development (details are given in the 1985 Guidelines, page 
22). The eight specific families are intended to be representative of a 
wide spectrum of aquatic life. For this reason it is not necessary that 
the specific organisms tested be actually present in the water body. 
EPA's application of its guidelines to develop the criteria matrix in 
this rule is judged by the Agency to be appropriate for all waters of 
the United States (U.S.), and to all ecosystems (1985 Guidelines, page 
4) including those waters of the U.S. and ecosystems in the State of 
California.
    Fresh water and salt water (including both estuarine and marine 
waters) have different chemical compositions, and freshwater and 
saltwater species often do not inhabit the same water. To provide 
additional accuracy, criteria are developed for fresh water and for 
salt water.
    For this rule, EPA updated freshwater aquatic life criteria 
contained in CWA section 304(a) criteria guidance first published in 
the early 1980's and later modified in the NTR, as amended, for the 
following ten pollutants: arsenic, cadmium, chromium (VI), copper, 
dieldrin, endrin, lindane (gamma BHC), nickel, pentachlorophenol, and 
zinc. The updates used as the basis for this rule are explained in a 
technical support document entitled, 1995 Updates: Water Quality 
Criteria Documents for the Protection of Aquatic Life in Ambient Water 
(U.S. EPA-820-B-96-001, September 1996), available in the 
administrative record to this rulemaking; this document presents the 
derivation of each of the final CMCs and CCCs and the toxicity studies 
from which the updated freshwater criteria for the ten pollutants were 
derived.
    The polychlorinated biphenyls (PCB) criteria in the criteria matrix 
for this rule differs from that in the NTR, as amended; for this rule, 
the criteria are expressed as the sum of seven aroclors, while for the 
NTR, as amended, the criteria are expressed for each of seven aroclors. 
The aquatic life criteria for PCBs in the CTR are based on the criteria 
contained in the 1980 criteria guidance document for PCBs which is 
included in the administrative record for this rule. This criteria 
document explains the derivation of aquatic life criteria based on 
total PCBs. For more information see the Response to Comments document 
for this rule. Today's chronic aquatic life criteria for PCBs are based 
on a final residue value (FRV). In EPA's guidelines for deriving 
aquatic life criteria, an FRV-based criterion is intended to prevent 
concentrations of pollutants in commercially or recreationally 
important aquatic species from affecting the marketability of those 
species or affecting the wildlife that consume aquatic life.
    The proposed CTR included an updated freshwater and saltwater 
aquatic life criteria for mercury. In today's final rule, EPA has 
reserved the mercury criteria for freshwater and saltwater aquatic 
life, but is promulgating human health criteria for mercury for all 
surface waters in California. In some instances, the human health 
mercury criteria included in today's final rule may not protect some 
aquatic species or threatened or endangered species. In such instances, 
more stringent mercury limits may be determined and implemented through 
use of the State's narrative criterion. The reasons for reserving the 
mercury aquatic life numbers are explained in further detail in Section 
L, Endangered Species Act.
a. Freshwater Acute Selenium Criterion
    EPA proposed a different freshwater acute aquatic life criterion 
for selenium for this rule than was promulgated in the NTR, as amended. 
EPA's proposed action was consistent with EPA's proposed selenium 
criterion maximum concentration for the Water Quality Guidance for the 
Great Lakes System (61 FR 58444, November 14, 1996). This proposal took 
into account data showing that selenium's two most prevalent oxidation 
states, selenite and selenate, present differing potentials for aquatic 
toxicity, as well as new data which indicated that various forms of 
selenium are additive. Additivity increases the toxicity of mixtures of 
different forms of the pollutant. The proposed approach produces a 
different selenium acute criterion concentration, or CMC, depending 
upon the relative proportions of selenite, selenate, and other forms of 
selenium that are present.
    The preamble to the August 5, 1997, proposed rule provided a 
lengthy discussion of this proposed criterion for the State of 
California. See 62 FR 42160-42208. EPA incorporates that discussion 
here as part of this rulemaking record. In 1996, a similar discussion 
was included in the proposed rule for the Great Lakes System. 
Commenters questioned several aspects of the Great Lakes proposal. EPA 
is continuing to respond to those comments, and to follow up with 
additional literature review and toxicity testing. In addition, the 
U.S. FWS and U.S. NMFS (collectively, the Services) are concerned that 
EPA's proposed criterion may not be sufficiently protective of certain 
threatened and endangered species in California. Because the Services 
believe there is a lack of data to show for certain that the proposed 
criterion would not affect threatened and endangered species, the 
Services prefer that EPA further investigate the protectiveness of the

[[Page 31690]]

criterion before finalizing the proposed criterion. Therefore, EPA is 
not promulgating a final acute freshwater selenium criterion at this 
time.
b. Dissolved Metals Criteria
    In December of 1992, in the NTR, EPA promulgated water quality 
criteria for several States that had failed to meet the requirements of 
CWA section 303(c)(2)(B). Included among the water quality criteria 
promulgated were numeric criteria for the protection of aquatic life 
for 11 metals: arsenic, cadmium, chromium (III), chromium (VI), copper, 
lead, mercury, nickel, selenium, silver and zinc. Criteria for two 
metals applied to the State of California: chromium III and selenium.
    The Agency received extensive public comment during the development 
of the NTR regarding the most appropriate approach for expressing the 
aquatic life metals criteria. The principal issue was the correlation 
between metals that are measured and metals that are bioavailable and 
toxic to aquatic life. It is now the Agency's policy that the use of 
dissolved metal to set and measure compliance with aquatic life water 
quality standards is the recommended approach, because dissolved metal 
more closely approximates the bioavailable fraction of the metal in the 
water column than does total recoverable metal.
    Since EPA's previous aquatic life criteria guidance had been 
expressed as total recoverable metal, to express the criteria as 
dissolved, conversion factors were developed to account for the 
possible presence of particulate metal in the laboratory toxicity tests 
used to develop the total recoverable criteria. EPA included a set of 
recommended freshwater conversion factors with its Metals Policy (see 
Office of Water Policy and Technical Guidance on Interpretation and 
Implementation of Aquatic Life Metals Criteria, Martha G. Prothro, 
Acting Assistant Administrator for Water, October 1, 1993). Based on 
additional laboratory evaluations that simulated the original toxicity 
tests, EPA refined the procedures used to develop freshwater conversion 
factors for aquatic life criteria. These new conversion factors were 
made available for public review and comment in the amendments to the 
NTR on May 4, 1995, at 60 FR 22229. They are also contained in today's 
rule at 40 CFR 131.38(b)(2).
    The preamble to the August 5, 1997, proposed rule provided a more 
detailed discussion of EPA's metals policy concerning the aquatic life 
water quality criteria for the State of California. See 62 FR 42160-
42208. EPA incorporates that discussion here as part of this rulemaking 
record. Many commenters strongly supported the Agency's policy on 
dissolved metals aquatic life criteria. A few commenters expressed an 
opinion that the metals policy may not provide criteria that are 
adequately protective of aquatic or other species. Responses to those 
comments are contained in a memo to the CTR record entitled 
``Discussion of the Use of Dissolved Metals in the CTR'' (February 1, 
2000, Jeanette Wiltse) and EPA's response to comments document which 
are both contained in the administrative record for the final rule.
    Calculation of Aquatic Life Dissolved Metals Criteria: Metals 
criteria values for aquatic life in today's rule in the matrix at 
131.38(b)(1) are shown as dissolved metal. These criteria have been 
calculated in one of two ways. For freshwater metals criteria that are 
hardness-dependent, the metals criteria value is calculated separately 
for each hardness using the table at 40 CFR 131.38(b)(2). (The 
hardness-dependent freshwater values presented in the matrix at 40 CFR 
131.38(b)(1) have been calculated using a hardness of 100 mg/l as CaCO3 
for illustrative purposes only.) The hardness-dependent criteria are 
then multiplied by the appropriate conversion factors in the table at 
40 CFR 131.38(b)(2). Saltwater and freshwater metals criteria that are 
not hardness-dependent are calculated by taking the total recoverable 
criteria values (from EPA's national section 304(a) criteria guidance, 
as updated and described in section F.2.a.) before rounding, and 
multiplying them by the appropriate conversion factors. The final 
dissolved metals criteria values, as they appear in the matrix at 40 
CFR 131.38(b)(1), are rounded to two significant figures.
    Translators for Dissolved to Total Recoverable Metals Limits: EPA's 
National Pollutant Discharge Elimination System (NPDES) regulations 
require that limits for metals in permits be stated as total 
recoverable in most cases (see 40 CFR 122.45(c)) except when an 
effluent guideline specifies the limitation in another form of the 
metal, the approved analytical methods measure only dissolved metal, or 
the permit writer expresses a metal's limit in another form (e.g., 
dissolved, specific valence, or total) when required to carry out 
provisions of the CWA. This is because the chemical conditions in 
ambient waters frequently differ substantially from those in the 
effluent and these differences result in changes in the partitioning 
between dissolved and absorbed forms of the metal. This means that if 
effluent limits were expressed in the dissolved form, additional 
particulate metal could dissolve in the receiving water causing the 
criteria to be exceeded. Expressing criteria as dissolved metal 
requires translation between different metal forms in the calculation 
of the permit limit so that a total recoverable permit limit can be 
established that will achieve water quality standards. Thus, it is 
important that permitting authorities and other authorities have the 
ability to translate between dissolved metal in ambient waters and 
total recoverable metal in effluent.
    EPA has completed guidance on the use of translators to convert 
from dissolved metals criteria to total recoverable permit limits. The 
document, The Metals Translator: Guidance for Calculating a Total 
Recoverable Permit Limit From a Dissolved Criterion (EPA 823-B-96-007, 
June 1996), is included in the administrative record for today's rule. 
This technical guidance examines how to develop a metals translator 
which is defined as the fraction of total recoverable metal in the 
downstream water that is dissolved, i.e., the dissolved metal 
concentration divided by the total recoverable metal concentration. A 
translator may take one of three forms: (1) It may be assumed to be 
equivalent to the criteria guidance conversion factors; (2) it may be 
developed directly as the ratio of dissolved to total recoverable 
metal; and (3) it may be developed through the use of a partition 
coefficient that is functionally related to the number of metal binding 
sites on the adsorbent in the water column (e.g., concentrations of 
total suspended solids or TSS). This guidance document discusses these 
three forms of translators, as well as field study designs, data 
generation and analysis, and site-specific study plans to generate 
site-specific translators.
    California Regional Water Quality Control Boards may use any of 
these methods in developing water quality-based permit limits to meet 
water quality standards based on dissolved metals criteria. EPA 
encourages the State to adopt a statewide policy on the use of 
translators so that the most appropriate method or methods are used 
consistently within California.
c. Application of Metals Criteria
    In selecting an approach for implementing the metals criteria, the 
principal issue is the correlation between metals that are measured and 
metals that are biologically available and toxic. In order to assure 
that the metals criteria are appropriate for the chemical conditions 
under which they are applied, EPA is providing for the

[[Page 31691]]

adjustment of the criteria through application of the ``water-effect 
ratio'' procedure. EPA notes that performing the testing to use a site-
specific water-effect ratio is optional on the part of the State.
    In the NTR, as amended, EPA identified the water-effect ratio (WER) 
procedure as a method for optional site-specific criteria development 
for certain metals. The WER approach compares bioavailability and 
toxicity of a specific pollutant in receiving waters and in laboratory 
waters. A WER is an appropriate measure of the toxicity of a material 
obtained in a site water divided by the same measure of the toxicity of 
the same material obtained simultaneously in a laboratory dilution 
water.
    On February 22, 1994, EPA issued Interim Guidance on the 
Determination and Use of the Water-Effect Ratios for Metals (EPA 823-B-
94-001) now incorporated into the updated Second Edition of the Water 
Quality Standards Handbook, Appendix L. A copy of the Handbook is 
contained in the administrative record for today's rule. In accordance 
with the WER guidance and where application of the WER is deemed 
appropriate, EPA strongly encourages the application of the WER on a 
watershed or water body basis as part of a water quality criteria in 
California as opposed to the application on a discharger-by-discharger 
basis through individual NPDES permits. This approach is technically 
sound and an efficient use of resources. However, discharger specific 
WERs for individual NPDES permit limits are possible and potentially 
efficient where the NPDES discharger is the only point source 
discharger to a specific water body.
    The rule requires a default WER value of 1.0 which will be assumed, 
if no site-specific WER is determined. To use a WER other than the 
default of 1.0, the rule requires that the WER must be determined as 
set forth in EPA's WER guidance or by another scientifically defensible 
method that has been adopted by the State as part of its water quality 
standards program and approved by EPA.
    The WER is a more comprehensive mechanism for addressing 
bioavailability issues than simply expressing the criteria in terms of 
dissolved metal. Consequently, expressing the criteria in terms of 
dissolved metal, as done in today's rule for California, does not 
completely eliminate the utility of the WER. This is particularly true 
for copper, a metal that forms reduced-toxicity complexes with 
dissolved organic matter.
    The Interim Guidance on Determination and Use of Water-Effect 
Ratios for Metals explains the relationship between WERs for dissolved 
criteria and WERs for total recoverable criteria. Dissolved 
measurements are to be used in the site-specific toxicity testing 
underlying the WERs for dissolved criteria. Because WERs for dissolved 
criteria generally are little affected by elevated particulate 
concentrations, EPA expects those WERs to be somewhat less than WERs 
for total recoverable criteria in such situations. Nevertheless, after 
the site-specific ratio of dissolved to total metal has been taken into 
account, EPA expects a permit limit derived using a WER for a dissolved 
criterion to be similar to the permit limit that would be derived from 
the WER for the corresponding total recoverable criterion.
d. Saltwater Copper Criteria
    The saltwater copper criteria for aquatic life in today's rule are 
4.8 g/l (CMC) and 3.1 g/l (CCC) in the dissolved 
form. These criteria reflect new data including data collected from 
studies for the New York/New Jersey Harbor and the San Francisco Bay 
indicating a need to revise the former copper 304(a) criteria guidance 
document to reflect a change in the saltwater CMC and CCC aquatic life 
values. These data also reflect a comprehensive literature search 
resulting in added toxicity test data for seven new species to the 
database for the saltwater copper criteria. EPA believes these new data 
have national implications and the national criteria guidance now 
contains a CMC of 4.8 g/l dissolved and a CCC of 3.1 
g/l dissolved. In the amendments to the NTR, EPA noticed the 
availability of data to support these changes to the NTR, and solicited 
comments. The data can be found in the draft document entitled, Ambient 
Water Quality Criteria--Copper, Addendum 1995. This document is 
available from the Office of Water Resource Center and is available for 
review in the administrative record for today's rule.
e. Chronic Averaging Period
    In establishing water quality criteria, EPA generally recommends an 
``averaging period'' which reflects the duration of exposure required 
to elicit effects in individual organisms (TSD, Appendix D-2). The 
criteria continuous concentration, or CCC, is intended to be the 
highest concentration that could be maintained indefinitely in a water 
body without causing an unacceptable effect on the aquatic community or 
its uses (TSD, Appendix D-1). As aquatic organisms do not generally 
experience steady exposure, but rather fluctuating exposures to 
pollutants, and because aquatic organisms can generally tolerate higher 
concentrations of pollutants over a shorter periods of time, EPA 
expects that the concentration of a pollutant can exceed the CCC 
without causing an unacceptable effect if (a) the magnitude and 
duration of exceedences are appropriately limited and (b) there are 
compensating periods of time during which the concentration is below 
the CCC. This is done by specifying a duration of an ``averaging 
period'' over which the average concentration should not exceed the CCC 
more often than specified by the frequency (TSD, Appendix D-1).
    EPA is promulgating a 4-day averaging period for chronic criteria, 
which means that measured or predicted ambient pollutant concentrations 
should be averaged over a 4-day period to determine attainment of 
chronic criteria. The State may apply to EPA for approval of an 
alternative averaging period. To do so, the State must submit to EPA 
the basis for such alternative averaging period.
    The most important consideration for setting an appropriate 
averaging period is the length of time that sensitive organisms can 
tolerate exposure to a pollutant at levels exceeding a criterion 
without showing adverse effects on survival, growth, or reproduction. 
EPA believes that the chronic averaging period must be shorter than the 
duration of the chronic tests on which the CCC is based, since, in some 
cases, effects are elicited before exposure of the entire duration. 
Most of the toxicity tests used to establish the chronic criteria are 
conducted using steady exposure to toxicants for a least 28 days (TSD, 
page 35). Some chronic tests, however, are much shorter than this (TSD, 
Appendix D-2). EPA selected the 4-day averaging period based on the 
shortest duration in which chronic test effects are sometimes observed 
for certain species and toxicants. In addition, EPA believes that the 
results of some chronic tests are due to an acute effect on a sensitive 
life stage that occurs some time during the test, rather than being 
caused by long-term stress or long-term accumulation of the test 
material in the organisms.
    Additional discussion of the rationale for the 4-day averaging 
period is contained in Appendix D of the TSD. Balancing all of the 
above factors and data, EPA believes that the 4-day averaging period 
falls within the scientifically reasonable range of values for choice 
of the averaging period, and is an appropriate length of time of

[[Page 31692]]

pollutant exposure to ensure protection of sensitive organisms.
    EPA established a 4-day averaging period in the NTR. In settlement 
of litigation on the NTR, EPA stated that it was ``in the midst of 
conducting, sponsoring, or planning research related to the basis for 
and application of'' water quality criteria and mentioned the issue of 
averaging period. See Partial Settlement Agreement in American Forest 
and Paper Ass'n, Inc. et al. v. U.S. EPA (Consolidated Case No. 93-0694 
(RMU), D.D.C.). EPA is re-evaluating issues raised about averaging 
periods and will, if appropriate, revise the 1985 Guidelines.
    EPA received public comment relevant to the averaging period during 
the comment period for the 1995 Amendments to the NTR (60 FR 22228, May 
4, 1995), although these public comments did not address the chronic 
averaging period separately from the allowable excursion frequency and 
the design flow. Comments recommended that EPA use the 30Q5 design flow 
for chronic criteria.
    While EPA is undertaking analysis of the chronic design conditions 
as part of the revisions to the 1985 Guidelines, EPA has not yet 
completed this work. Until this work is complete, for the reasons set 
forth in the TSD, EPA continues to believe that the 4-day chronic 
averaging period represents a reasonable, defensible value for this 
parameter.
    EPA added language to the final rule which will enable the State to 
adopt alternative averaging periods and frequencies and associated 
design flows where appropriate. The State may apply to EPA for approval 
of alternative averaging periods and frequencies and related design 
flows; the State must submit the bases for any changes. Before 
approving any change, EPA will publish for public comment, a notice 
proposing the changes.
f. Hardness
    Freshwater aquatic life criteria for certain metals are expressed 
as a function of hardness because hardness and/or water quality 
characteristics that are usually correlated with hardness can reduce or 
increase the toxicities of some metals. Hardness is used as a surrogate 
for a number of water quality characteristics which affect the toxicity 
of metals in a variety of ways. Increasing hardness has the effect of 
decreasing the toxicity of metals. Water quality criteria to protect 
aquatic life may be calculated at different concentrations of 
hardnesses measured in milligrams per liter (mg/l) as calcium carbonate 
(CaCO3).
    Section 131.38(b)(2) of the final rule presents the hardness-
dependent equations for freshwater metals criteria. For example, using 
the equation for zinc, the total recoverable CMCs at a hardness of 10, 
50, 100 or 200 mg/l as CaCO3 are 17, 67, 120 and 220 
micrograms per liter (g/l), respectively. Thus, the specific 
value in the table in the regulatory text is for illustrative purposes 
only. Most of the data used to develop these hardness equations for 
deriving aquatic life criteria for metals were in the range of 25 mg/l 
to 400 mg/l as CaCO3, and the formulas are therefore most 
accurate in this range. The majority of surface waters nationwide and 
in California have a hardness of less than 400 mg/l as 
CaCO3.
    In the past, EPA generally recommended that 25 mg/l as 
CaCO3 be used as a default hardness value in deriving 
freshwater aquatic life criteria for metals when the ambient (or 
actual) hardness value is below 25 mg/l as CaCO3. However, 
use of the approach results in criteria that may not be fully 
protective. Therefore, for waters with a hardness of less than 25 mg/l 
as CaCO3, criteria should be calculated using the actual 
ambient hardness of the surface water.
    In the past, EPA generally recommended that if the hardness was 
over 400 mg/l, two options were available: (1) Calculate the criterion 
using a default WER of 1.0 and using a hardness of 400 mg/l in the 
hardness equation; or (2) calculate the criterion using a WER and the 
actual ambient hardness of the surface water in the equation. Use of 
the second option is expected to result in the level of protection 
intended in the 1985 Guidelines whereas use of the first option is 
thought to result in an even more protective aquatic life criterion. At 
high hardness there is an indication that hardness and related 
inorganic water quality characteristics do not have as much of an 
effect on toxicity of metals as they do at lower hardnesses. Related 
water quality characteristics do not correlate as well at higher 
hardnesses as they do at lower hardnesses. Therefore, if hardness is 
over 400 mg/l as CaCO3, a hardness of 400 mg/l as 
CaCO3 should be used with a default WER of 1.0; 
alternatively, the WER and actual hardness of the surface water may be 
used.
    EPA requested comments in the NTR amendments on the use of actual 
ambient hardness for calculating criteria when the hardness is below 25 
mg/l as CaCO3, and when hardness is greater than 400 mg/l as 
CaCO3. Most of the comments received were in favor of using 
the actual hardness with the use of the water-effect ratio (1.0 unless 
otherwise specified by the permitting authority) when the hardness is 
greater than 400 mg/l as CaCO3. A few commenters did not 
want the water-effect ratio to be mandatory in calculating hardness, 
and other commenters had concerns about being responsible for deriving 
an appropriate water-effect ratio. Overall, the commenters were in 
favor of using the actual hardness when calculating hardness-dependent 
freshwater metals criteria for hardness between 0-400 mg/l as 
CaCO3. EPA took those comments into account in promulgating 
today's rule.
    A hardness equation is most accurate when the relationships between 
hardness and the other important inorganic constituents, notably 
alkalinity and pH, are nearly identical in all of the dilution waters 
used in the toxicity tests and in the surface waters to which the 
equation is to be applied. If an effluent raises hardness but not 
alkalinity and/or pH, using the hardness of the downstream water might 
provide a lower level of protection than intended by the 1985 
guidelines. If it appears that an effluent causes hardness to be 
inconsistent with alkalinity and/or pH, the intended level of 
protection will usually be maintained or exceeded if either (1) data 
are available to demonstrate that alkalinity and/or pH do not affect 
the toxicity of the metal, or (2) the hardness used in the hardness 
equation is the hardness of upstream water that does not contain the 
effluent. The level of protection intended by the 1985 guidelines can 
also be provided by using the WER procedure.
    In some cases, capping hardness at 400 mg/l might result in a level 
of protection that is higher than that intended by the 1985 guidelines, 
but any such increase in the level of protection can be overcome by use 
of the WER procedure. For metals whose criteria are expressed as 
hardness equations, use of the WER procedure will generally be intended 
to account for effects of such water quality characteristics as total 
organic carbon on the toxicities of metals. The WER procedure is 
equally useful for accounting for any deviation from a hardness 
equation in a site water.

3. Human Health Criteria

    EPA's CWA section 304(a) human health criteria guidance provides 
criteria recommendations to minimize adverse human effects due to 
substances in ambient water. EPA's CWA section 304(a) criteria guidance 
for human health are based on two types of

[[Page 31693]]

toxicological endpoints: (1) carcinogenicity and (2) systemic toxicity 
(i.e., all other adverse effects other than cancer). Thus, there are 
two procedures for assessing these health effects: one for carcinogens 
and one for non-carcinogens.
    If there are no data on how a chemical agent causes cancer, EPA's 
existing human health guidelines assume that carcinogenicity is a 
``non-threshold phenomenon,'' that is, there are no ``safe'' or ``no-
effect levels'' because even extremely small doses are assumed to cause 
a finite increase in the incidence of the effect (i.e., cancer). 
Therefore, EPA's water quality criteria guidance for carcinogens are 
presented as pollutant concentrations corresponding to increases in the 
risk of developing cancer. See Human Health Guidelines at 45 FR 79347.
    With existing criteria, pollutants that do not manifest any 
apparent carcinogenic effect in animal studies (i.e., systemic 
toxicants), EPA assumes that the pollutant has a threshold below which 
no effect will be observed. This assumption is based on the premise 
that a physiological mechanism exists within living organisms to avoid 
or overcome the adverse effect of the pollutant below the threshold 
concentration.

    Note: Recent changes in the Agency's cancer guidelines 
addressing these assumptions are described in the Draft Water 
Quality Criteria Methodology: Human Health, 63 FR 43756, August 14, 
1998.


    The human health risks of a substance cannot be determined with any 
degree of confidence unless dose-response relationships are quantified. 
Therefore, a dose-response assessment is required before a criterion 
can be calculated. The dose-response assessment determines the 
quantitative relationships between the amount of exposure to a 
substance and the onset of toxic injury or disease. Data for 
determining dose-response relationships are typically derived from 
animal studies, or less frequently, from epidemiological studies in 
exposed populations.
    The dose-response information needed for carcinogens is an estimate 
of the carcinogenic potency of the compound. Carcinogenic potency is 
defined here as a general term for a chemical's human cancer-causing 
potential. This term is often used loosely to refer to the more 
specific carcinogenic or cancer slope factor which is defined as an 
estimate of carcinogenic potency derived from animal studies or 
epidemiological data of human exposure. It is based on extrapolation 
from test exposures of high doses over relatively short periods of time 
to more realistic low doses over a lifetime exposure period by use of 
linear extrapolation models. The cancer slope factor, q1*, is EPA's 
estimate of carcinogenic potency and is intended to be a conservative 
upper bound estimate (e.g. 95% upper bound confidence limit).
    For non-carcinogens, EPA uses the reference dose (RfD) as the dose-
response parameter in calculating the criteria. For non-carcinogens, 
oral RfD assessments (hereinafter simply ``RfDs'') are developed based 
on pollutant concentrations that cause threshold effects. The RfD is an 
estimate (with uncertainty spanning perhaps an order of magnitude) of a 
daily exposure to the human population (including sensitive subgroups) 
that is likely to be without appreciable risk of deleterious effects 
during a lifetime. See Human Health Guidelines. The RfD was formerly 
referred to as an ``Acceptable Daily Intake'' or ADI. The RfD is useful 
as a reference point for gauging the potential effect of other doses. 
Doses that are less than the RfD are not likely to be associated with 
any health risks, and are therefore less likely to be of regulatory 
concern. As the frequency of exposures exceeding the RfD increases and 
as the size of the excess increases, the probability increases that 
adverse effect may be observed in a human population. Nonetheless, a 
clear conclusion cannot be categorically drawn that all doses below the 
RfD are ``acceptable'' and that all doses in excess of the RfD are 
``unacceptable.'' In extrapolating non-carcinogen animal test data to 
humans to derive an RfD, EPA divides either a No Observed-Adverse 
Effect Level (NOAEL), Lowest Observed Adverse Effect Level (LOAEL), or 
other benchmark dose observed in animal studies by an ``uncertainty 
factor'' which is based on professional judgment of toxicologists and 
typically ranges from 10 to 10,000.
    For CWA section 304(a) human health criteria development, EPA 
typically considers only exposures to a pollutant that occur through 
the ingestion of water and contaminated fish and shellfish. Thus, the 
criteria are based on an assessment of risks related to the surface 
water exposure route only where designated uses are drinking water and 
fish and shellfish consumption.
    The assumed exposure pathways in calculating the criteria are the 
consumption of 2 liters per day of water at the criteria concentration 
and the consumption of 6.5 grams per day of fish and shellfish 
contaminated at a level equal to the criteria concentration but 
multiplied by a ``bioconcentration factor.'' The use of fish and 
shellfish consumption as an exposure factor requires the quantification 
of pollutant residues in the edible portions of the ingested species.
    Bioconcentration factors (BCFs) are used to relate pollutant 
residues in aquatic organisms to the pollutant concentration in ambient 
waters. BCFs are quantified by various procedures depending on the 
lipid solubility of the pollutant. For lipid soluble pollutants, the 
average BCF is calculated from the weighted average percent lipids in 
the edible portions of fish and shellfish, which is about 3%; or it is 
calculated from theoretical considerations using the octanol/water 
partition coefficient. For non-lipid soluble compounds, the BCF is 
determined empirically. The assumed water consumption is taken from the 
National Academy of Sciences publication Drinking Water and Health 
(1977). (Referenced in the Human Health Guidelines.) This value is 
appropriate as it includes a margin of safety so that the general 
population is protected. See also EPA's discussion of the 2.0 liters/
day assumption at 61 FR 65183 (Dec. 11, 1996). The 6.5 grams per day 
contaminated fish and shellfish consumption value was equivalent to the 
average per-capita consumption rate of all (contaminated and non-
contaminated) freshwater and estuarine fish and shellfish for the U.S. 
population. See Human Health Guidelines.
    EPA assumes in calculating water quality criteria that the exposed 
individual is an average adult with body weight of 70 kilograms. EPA 
assumes 6.5 grams per day of contaminated fish and shellfish 
consumption and 2.0 liters per day of contaminated drinking water 
consumption for a 70 kilogram person in calculating the criteria. 
Regarding issues concerning criteria development and differences in 
dose per kilogram of body weight, RfDs are always derived based on the 
most sensitive health effect endpoint. Therefore, when that basis is 
due to a chronic or lifetime health effect, the exposure parameters 
assume the exposed individual to be the average adult, as indicated 
above.
    In the absence of this final rule, there may be particular risks to 
children. EPA believes that children are protected by the human health 
criteria contained in this final rule. Children are protected against 
other less sensitive adverse health endpoints due to the conservative 
way that the RfDs are derived. An RfD is a public health protective 
endpoint. It is an amount of a chemical that can be consumed on a daily 
basis for a lifetime without expecting an adverse effect. RfDs are 
based on sensitive health endpoints and

[[Page 31694]]

are calculated to be protective for sensitive human sub-populations 
including children. If the basis of the RfD was due to an acute or 
shorter-term developmental effect, EPA uses exposure parameters other 
than those indicated above. Specifically, EPA uses parameters most 
representative of the population of concern (e.g., the health criteria 
for nitrates based on infant exposure parameters). For carcinogens, the 
risk assessments are upper bound one in a million (10-6) 
lifetime risk numbers. The risk to children is not likely to exceed 
these upper bounds estimates and may be zero at low doses. The exposure 
assumptions for drinking water and fish protect children because they 
are conservative for infants and children. EPA assumes 2 liters of 
untreated surface water and 6.5 grams of freshwater and estuarine fish 
are consumed each day. EPA believes the adult fish consumption 
assumption is conservative for children because children generally 
consume marine fish not freshwater and estuarine.
    EPA has a process to develop a scientific consensus on oral 
reference dose assessments and carcinogenicity assessments (hereinafter 
simply cancer slope factors or slope factors or q1*s). Through this 
process, EPA develops a consensus of Agency opinion which is then used 
throughout EPA in risk management decision-making. EPA maintains an 
electronic data base which contains the official Agency consensus for 
oral RfD assessments and carcinogenicity assessments which is known as 
the Integrated Risk Information System (IRIS). It is available for use 
by the public on the National Institutes of Health's National Library 
of Medicine's TOXNET system, and through diskettes from the National 
Technical Information Service (NTIS). (NTIS access number is PB 90-
591330.)
    Section 304(a)(1) of the CWA requires EPA to periodically revise 
its criteria guidance to reflect the latest scientific knowledge: ``(A) 
On the kind and extent of all identifiable effects on health and 
welfare * * *; (B) on the concentration and dispersal of pollutants, or 
their byproducts, through biological, physical, and chemical processes; 
and (C) on the effects of pollutants on the biological community 
diversity, productivity, and stability, including information on the 
factors affecting eutrophication rates of organic and inorganic 
sedimentation for varying types of receiving waters.'' In developing 
up-to-date water quality criteria for the protection of human health, 
EPA uses the most recent IRIS values (RfDs and q1*s) as the 
toxicological basis in the criterion calculation. IRIS reflects EPA's 
most current consensus on the toxicological assessment for a chemical. 
In developing the criteria in today's rule, the IRIS values as of 
October 1996 were used together with currently accepted exposure 
parameters for bioconcentration, fish and shellfish and water 
consumption, and body weight. The IRIS cover sheet for each pollutant 
criteria included in today's rule is contained in the administrative 
record.
    For the human health criteria included in today's rule, EPA used 
the Human Health Guidelines on which criteria recommendations from the 
appropriate CWA section 304(a) criteria guidance document were based. 
(These documents are also placed in the administrative record for 
today's rule.) Where EPA has changed any parameters in IRIS used in 
criteria derivation since issuance of the criteria guidance document, 
EPA recalculated the criteria recommendation with the latest IRIS 
information. Thus, there are differences between the original 1980 
criteria guidance document recommendations, and those in this rule, but 
this rule presents EPA's most current CWA section 304(a) criteria 
recommendation. The basis (q1* or RfD) and BCF for each pollutant 
criterion in today's rule is contained in the rule's Administrative 
Record Matrix which is included in the administrative record for the 
rule. In addition, all recalculated human health numbers are denoted by 
an ``a'' in the criteria matrix in 40 CFR 131.38(b)(1) of the rule. The 
pollutants for which a revised human health criterion has been 
calculated since the December 1992 NTR include:
mercury
dichlorobromomethane
1,2-dichloropropane
1,2-trans-dichloroethylene
2,4-dimethylphenol
acenaphthene
benzo(a)anthracene
benzo(a)pyrene
benzo(b)flouranthene
benzo(k)flouranthene
2-chloronaphthalene
chrysene
dibenzo(a,h)anthracene
indeno(1,2,3-cd)pyrene
N-nitrosodi-n-propylamine
alpha-endosulfan
beta-endosulfan
endosulfan sulfate
2-chlorophenol
butylbenzyl phthalate
polychlorinated biphenyls.

    In November of 1991, the proposed NTR presented criteria for 
several pollutants in parentheses. These were pollutants for which, in 
1980, insufficient information existed to develop human health water 
quality criteria, but for which, in 1991, sufficient information 
existed. Since these criteria did not undergo the public review and 
comment in a manner similar to the other water quality criteria 
presented in the NTR (for which sufficient information was available in 
1980 to develop a criterion, as presented in the 1980 criteria guidance 
documents), they were not proposed for adoption into the water quality 
criteria, but were presented to serve as notice for inclusion in future 
State triennial reviews. Today's rule promulgates criteria for these 
nine pollutants:

copper
1, 2-dichloropropane
1,2-trans-dichloroethylene
2,4-dimethylphenol
acenaphthene
2-chloronaphthalene
N-nitrosodi-n-propylamine
2-chlorophenol
butylbenzene phthalate

    All the criteria are based on IRIS values--either an RfD or q1*--
which were listed on IRIS as of November 1991, the date of the proposed 
NTR. These values have not changed since the final NTR was published in 
December of 1992. The rule's Administrative Record Matrix in the 
administrative record of today's rule contains the specific RfDs, q1*s, 
and BCFs used in calculating these criteria.
    Proposed Changes to the Human Health Criteria Methodology: EPA 
recently proposed revisions to the 1980 ambient water quality criteria 
derivation guidelines (the Human Health Guidelines). See Draft Water 
Quality Criteria Methodology: Human Health, 63 FR 43756, August 14, 
1998; see also Draft Water Quality Criteria Methodology: Human Health, 
U.S. EPA Office of Water, EPA 822-Z-98-001. The EPA revisions consist 
of five documents: Draft Water Quality Criteria Methodology: Human 
Health, EPA 822-Z-98-001; Ambient Water Quality Criteria Derivation 
Methodology Human Health, Technical Support Document, Final Draft, EPA-
822-B-98-005; and three Ambient Water Quality Criteria for the 
Protection of Human Health, Drafts--one each for Acrylonitrile, 1,3-
Dichloropropene (1,3-DCP), and Hexachlorobutadiene (HCBD), 
respectively, EPA-822-R-98-006, -005, and -004. All five documents are 
contained in the administrative record for today's rule.
    The proposed methodology revisions reflect significant scientific 
advances that have occurred during the past nineteen years in such key 
areas as cancer and noncancer risk assessments, exposure assessments 
and bioaccumulation. For specific details on

[[Page 31695]]

these proposed changes and others, please refer to the Federal Register 
notice or the EPA document.
    It should be noted that some of the proposed changes may result in 
significant numeric changes in the ambient water quality criteria. 
However, EPA will continue to rely on existing criteria as the basis 
for regulatory and non-regulatory decisions, until EPA revises and 
reissues a 304(a) criteria guidance using the revised final human 
health criteria methodology. The existing criteria are still viewed as 
scientifically acceptable by EPA. The intention of the proposed 
methodology revisions is to present the latest scientific advancements 
in the areas of risk and exposure assessment in order to incrementally 
improve the already sound toxicological and exposure bases for these 
criteria. As EPA's current human health criteria are the product of 
many years worth of development and peer review, it is reasonable to 
assume that revisiting all existing criteria, and incorporating peer 
review into such review, could require comparable amounts of time and 
resources. Given these circumstances, EPA proposed a process for 
revisiting these criteria as part of the overall revisions to the 
methodology for deriving human health criteria. This process is 
discussed in the Implementation Section of the Notice of Draft 
Revisions to the Methodology for Deriving Ambient Water Quality 
Criteria for the Protection of Human Health (see 63 FR 43771-43776, 
August 14, 1998).
    The State of California in its Ocean Plan, adopted in 1990 and 
approved by EPA in 1991, established numeric water quality criteria 
using an average fish and shellfish consumption rate of 23 grams per 
day. This value is based on an earlier California Department of Health 
Services estimate. The State is currently in the process of readopting 
its water quality control plans for inland surface waters, enclosed 
bays, and estuaries. The State intends to consider information on fish 
and shellfish consumption rates evaluated and summarized in a report 
prepared by the State's Pesticide and Environmental Toxicology Section 
of the Office of Environmental Health Hazard Assessment of the 
California Environmental Protection Agency. The report, entitled, 
Chemicals in Fish Report No. 1: Consumption of Fish and Shellfish in 
California and the United States, was published in final draft form in 
July of 1997, and released to the public on September 16, 1997. The 
report is currently undergoing final evaluation, and is expected to 
published in final form in the near future. This final draft report is 
contained in the administrative record for today's rule. Although EPA 
has not used this fish consumption value here because this information 
has not yet been finalized, the State may use any appropriate higher 
state-specific fish and shellfish consumption rates in its readoption 
of criteria in its statewide plans.
a. 2,3,7,8-TCDD (Dioxin) Criteria
    In today's action, EPA is promulgating human health water quality 
criteria for 2,3,7,8-tetrachlorodibenzo-p-dioxin (``dioxin'') at the 
same levels as promulgated in the NTR, as amended. These criteria are 
derived from EPA's 1984 CWA section 304(a) criteria guidance document 
for dioxin.
    For National Pollutant Discharge Elimination System (NPDES) 
purposes, EPA supports the regulation of other dioxin and dioxin-like 
compounds through the use of toxicity equivalencies or TEQs in NPDES 
permits (see discussion below). For California waters, if the discharge 
of dioxin or dioxin-like compounds has reasonable potential to cause or 
contribute to a violation of a narrative criterion, numeric water 
quality-based effluent limits for dioxin or dioxin-like compounds 
should be included in NPDES permits and should be expressed using a TEQ 
scheme.
    EPA has been evaluating the health threat posed by dioxin nearly 
continuously for over two decades. Following issuance of the 1984 
criteria guidance document, evaluating the health effects of dioxin and 
recommending human health criteria for dioxin, EPA prepared draft 
reassessments reviewing new scientific information relating to dioxin 
in 1985 and 1988. EPA's Science Advisory Board (SAB), reviewing the 
1988 draft reassessment, concluded that while the risk assessment 
approach used in 1984 criteria guidance document had inadequacies, a 
better alternative was unavailable (see SAB's Dioxin Panel Review of 
Documents from the Office or Research and Development relating to the 
Risk and Exposure Assessment of 2,3,7,8-TCDD (EPA-SAB-EC-90-003, 
November 28, 1989) included in the administrative record for today's 
rule). Between 1988 and 1990, EPA issued numerous reports and guidances 
relating to the control of dioxin discharges from pulp and paper mills. 
See e.g., EPA Memorandum, ``Strategy for the Regulation of Discharges 
of PHDDs & PHDFs from Pulp and Paper Mills to the Waters of the United 
States,'' from Assistant Administrator for Water to Regional Water 
Management Division Directors and NPDES State Directors, dated May 21, 
1990 (AR NL-16); EPA Memorandum, ``State Policies, Water Quality 
Standards, and Permit Limitations Related to 2,3,7,8-TCDD in Surface 
Water,'' from the Assistant Administrator for Water to Regional Water 
Management Division Directors, dated January 5, 1990 (AR VA-66). These 
documents are available in the administrative record for today's rule.
    In 1991, EPA's Administrator announced another scientific 
reassessment of the risks of exposure to dioxin (see Memorandum from 
Administrator William K. Reilly to Erich W. Bretthauer, Assistant 
Administrator for Research and Development and E. Donald Elliott, 
General Counsel, entitled Dioxin: Follow-Up to Briefing on Scientific 
Developments, April 8, 1991, included in the administrative record for 
today's rule). At that time, the Administrator made clear that while 
the reassessment was underway, EPA would continue to regulate dioxin in 
accordance with existing Agency policy. Thereafter, the Agency 
proceeded to regulate dioxin in a number of environmental programs, 
including standards under the Safe Drinking Water Act and the CWA.
    The Administrator's promulgation of the dioxin human health 
criteria in the 1992 NTR affirmed the Agency's decision that the 
ongoing reassessment should not defer or delay regulating this potent 
contaminant, and further, that the risk assessment in the 1984 criteria 
guidance document for dioxin continued to be scientifically defensible. 
Until the reassessment process was completed, the Agency could not 
``say with any certainty what the degree or directions of any changes 
in the risk estimates might be'' (57 FR 60863-64).
    The basis for the dioxin criteria as well as the decision to 
include the dioxin criteria in the 1992 NTR pending the results of the 
reassessment were challenged. See American Forest and Paper Ass'n, Inc. 
et al. v. U.S. EPA (Consolidated Case No. 93-0694 (RMU) D.D.C.). By 
order dated September 4, 1996, the Court upheld EPA's decision. EPA's 
brief and the Court's decision are included in the administrative 
record for today's rule.
    EPA has undertaken significant effort toward completion of the 
dioxin reassessment. On September 13, 1994, EPA released for public 
review and comment a draft reassessment of toxicity and exposure to 
dioxin. See Health Assessment Document for 2,3,7,8-Tetrachlorobenzo-p-
Dioxin (TCDD) and Related Compounds, U.S. EPA, 1994. EPA is currently 
addressing comments made by the public and the SAB and anticipates that 
the final

[[Page 31696]]

revised reassessment will go to the SAB in the near future. With 
today's rule, the Agency reaffirms that, notwithstanding the on-going 
risk reassessment, EPA intends to continue to regulate dioxin to avoid 
further harm to public health, and the basis for the dioxin criteria, 
both in terms of the cancer potency and the exposure estimates, remains 
scientifically defensible. The fact that EPA is reassessing the risk of 
dioxin, virtually a continuous process to evaluate new scientific 
information, does not mean that the current risk assessment is 
``wrong''. It continues to be EPA's position that until the risk 
assessment for dioxin is revised, EPA supports and will continue to use 
the existing risk assessment for the regulation of dioxin in the 
environment. Accordingly, EPA today promulgates dioxin criteria based 
on the 1984 criteria guidance document for dioxin and promulgated in 
the NTR in 1992.
    Toxicity Equivalency: The State of California, in its 1991 water 
quality control plans, adopted human health criteria for dioxin and 
dioxin-like compounds based on the concept of toxicity equivalency 
(TEQ) using toxicity equivalency factors (TEFs). EPA Region 9 reviewed 
and approved the State's use of the TEQ concept and TEFs in setting the 
State's human health water quality criteria for dioxin and dioxin-like 
compounds.
    In 1987, EPA formally embraced the TEQ concept as an interim 
procedure to estimate the risks associated with exposures to 210 
chlorinated dibenzo-p-dioxin and chlorinated dibenzofuran (CDD/CDF) 
congeners, including 2,3,7,8-TCDD. This procedure uses a set of derived 
TEFs to convert the concentration of any CDD/CDF congener into an 
equivalent concentration of 2,3,7,8-TCDD. In 1989, EPA updated its TEFs 
based on an examination of relevant scientific evidence and a 
recognition of the value of international consistency. This updated 
information can be found in EPA's 1989 Update to the Interim Procedures 
for Estimating Risks Associated with Exposures to Mixtures of 
Chlorinated Dibenzo-p-dioxins and -dibenzofurans (CDDs and CDFs) (EPA/
625/3-89/016, March 1989). EPA had been active in an international 
effort aimed at adopting a common set of TEFs (International TEFs/89 or 
I-TEFs/89), to facilitate information exchange on environmental 
contamination of CDD/CDF. This document reflects EPA's support of an 
internationally consistent set of TEFs, the I-TEFs/89. EPA uses I-TEFs/
89 in many of its regulatory programs.
    In 1994, the World Health Organization (WHO) revised the TEF scheme 
for dioxins and furans to include toxicity from dioxin-like compounds 
(Ahlborg et al., 1994). However, no changes were made to the TEFs for 
dioxins and furans. In 1998, the WHO re-evaluated and revised the 
previously established TEFs for dioxins (Ds), furans (Fs) and dioxin-
like compounds (Vanden Bers, 1998). The nomenclature for this TEF 
scheme is TEQDFP-WHO98, where TEQ represents the 2,3,7,8-TCDD Toxic 
Equivalence of the mixture, and the subscript DFP indicates that 
dioxins (Ds) furans (Fs) and dioxin-like compounds (P) are included in 
the TEF scheme. The subscript 98 following WHO displays the year 
changes were made to the TEF scheme.
    EPA intends to use the 1998 WHO TEF scheme in the near future. At 
this point however, EPA will support the use of either the 1989 interim 
procedures or the 1998 WHO TEF scheme but encourages the use of the 
1998 WHO TEF scheme in State programs. EPA expects California to use a 
TEF scheme in implementing the 2,3,7,8-TCDD water quality criteria 
contained in today's rule. The TEQ and TEF approach provide a 
methodology for setting NPDES water quality-based permit limits that 
are protective of human health for dioxin and dioxin-like compounds.
    Several commenters requested EPA to promulgate criteria for other 
forms of dioxin, in addition to 2,3,7,8-TCDD. EPA's draft reassessment 
for dioxin examines toxicity based on the TEQ concept and I-TEFs/89. 
When EPA completes the dioxin reassessment, the Agency intends to adopt 
revised 304(a) water quality criteria guidance based on the 
reassessment for dioxin. If necessary, EPA will then act to amend the 
NTR and CTR to reflect the revised 304(a) water quality criteria 
guidance.
b. Arsenic Criteria
    EPA is not promulgating human health criteria for arsenic in 
today's rule. EPA recognizes that it promulgated human health water 
quality criteria for arsenic for a number of States in 1992, in the 
NTR, based on EPA's 1980 section 304(a) criteria guidance for arsenic 
established, in part, from IRIS values current at that time. However, a 
number of issues and uncertainties existed at the time of the CTR 
proposal concerning the health effects of arsenic. These issues and 
uncertainties were summarized in ``Issues Related to Health Risk of 
Arsenic'' which is contained in the administrative record for today's 
rule. During the period of this rulemaking action, EPA commissioned a 
study of arsenic health effects by the National Research Council (NRC) 
arm of the National Academy of Sciences. EPA received the NRC report in 
March of 1999. EPA scientists reviewed the report, which recommended 
that EPA lower the Safe Drinking Water Act arsenic maximum contaminant 
level (MCL) as soon as possible (The arsenic MCL is currently 50 
g/l.) The bladder cancer analysis in the NRC report will 
provide part of the basis for the risk assessment of a proposed revised 
arsenic MCL in the near future. After promulgating a revised MCL for 
drinking water, the Agency plans to revise the CWA 304(a) human health 
criteria for arsenic in order to harmonize the two standards. Today's 
rule defers promulgating arsenic criteria based on the Agency's 
previous risk assessment of skin cancer. In the meantime, permitting 
authorities in California should rely on existing narrative water 
quality criteria to establish effluent limitations as necessary for 
arsenic. California has previously expressed its science and policy 
position by establishing a criterion level of 5 g/l for 
arsenic. Permitting authorities may, among other considerations, 
consider that value when evaluating and interpreting narrative water 
quality criteria.
c. Mercury Criteria
    The human health criteria promulgated here use the latest RfD in 
EPA's Integrated Risk Information System (IRIS) and the weighted 
average practical bioconcentration factor (PBCF) from the 1980 section 
304(a) criteria guidance document for mercury. EPA considered the 
approach used in the Great Lakes Water Quality Guidance (``Guidance'') 
incorporating Bioaccumulation Factors (BAFs), but rejected this 
approach for reasons outlined below. The equation used here to derive 
an ambient water quality criterion for mercury from exposure to 
organisms and water is:
[GRAPHIC] [TIFF OMITTED] TR18MY00.011

Where:

RfD = Reference Dose
BW = Body Weight
WC = Water Consumption
FC = Total Fish and Shellfish Consumption per Day
PBCF = Practical Bioconcentration Factor (weighted average)

    For mercury, the most current RfD from IRIS is 1 x 10-4 
mg/kg/day. The RfD used a benchmark dose as an estimate of a No 
Observed Adverse Effect Level (NOAEL). The benchmark dose was 
calculated by applying a Weibel model

[[Page 31697]]

for extra risk to all neurological effects observed in 81 Iraqi 
children exposed in utero as reported in Marsh, et. al. (1987). 
Maternal hair mercury was the measure of exposure. Extra risk refers to 
an adjustment for background incidence of a given health effect. 
Specifically, the extra risk is the added incidence of observing an 
effect above the background rate relative to the proportion of the 
population of interest that is not expected to exhibit such as effect. 
The resulting estimate was the lower 95% statistical bound on the 10% 
extra risk; this was 11 ppm mercury in maternal hair. This dose in hair 
was converted to an equivalent ingested amount by applying a model 
based on data from human studies; the resulting benchmark dose was 1 x 
10-3 mg/kg body weight /day. The RfD was calculated by 
dividing the benchmark dose by a composite uncertainty factor of 10. 
The uncertainty factor was used to account for variability in the human 
population, in particular the wide variation in biological half-life of 
methylmercury and the variation that is observed in the ration of hair 
mercury to mercury in the blood. In addition the uncertainty factor 
accounts for lack of a two-generation reproductive study and the lack 
of data on long term effects of childhood mercury exposures. The RfD 
thus calculated is 1 x 10-4 mg/kg body weight/day or 0.1 
g/kg/day. The body weight used in the equation for the mercury 
criteria, as discussed in the Human Health Guidelines, is a mean adult 
human body weight of 70 kg. The drinking water consumption rate, as 
discussed in the Human Health Guidelines, is 2.0 liters per day.
    The bioconcentration factor or BCF is defined as the ratio of 
chemical concentration in the organism to that in surrounding water. 
Bioconcentration occurs through uptake and retention of a substance 
from water only, through gill membranes or other external body 
surfaces. In the context of setting exposure criteria it is generally 
understood that the terms ``BCF'' and ``steady-state BCF'' are 
synonymous. A steady-state condition occurs when the organism is 
exposed for a sufficient length of time that the ratio does not change 
substantially.
    The BCFs that were used herein are the ``Practical Bioconcentration 
Factors (PBCFs)'' that were derived in 1980: 5500 for fresh water, 3765 
for estuarine coastal waters, and 9000 for open oceans. See pages C-
100-1 of Ambient Water Quality Criteria for Mercury (EPA 440/5-80-058) 
for a complete discussion on the PBCF. Because of the way they were 
derived, these PBCFs take into account uptake from food as well as 
uptake from water. A weighted average PBCF was calculated to take into 
account the average consumption from the three waters using the 
following equation:
[GRAPHIC] [TIFF OMITTED] TR18MY00.012

Given the large value for the weighted average PBCF, the contribution 
of drinking water to total daily intake is negligible so that 
assumptions concerning the chemical form of mercury in drinking water 
become less important. The human health mercury criteria promulgated 
for this rule are based on the latest RfD as listed in IRIS and a 
weighted PBCF from the 1980 Sec. 304(a) criteria guidance document for 
mercury.
    On March 23, 1995 (60 FR 15366), EPA promulgated the Great Lakes 
Water Quality Guidance (``Guidance''). The Guidance incorporated 
bioaccumulation factors (BAFs) in the derivation of criteria to protect 
human health because it is believed that BAFs are a better predictor 
than BCFs of the concentration of a chemical within fish tissue since 
BAFs include consideration of the uptake of contaminants from all 
routes of exposure. A bioaccumulation factor is defined as the ratio 
(in L/kg) of a substance's concentration in tissue to the concentration 
in the ambient water, in situations where both the organism and its 
food are exposed and the ratio does not change substantially over time. 
The final Great Lakes Guidance establishes a hierarchy of four methods 
for deriving BAFs for non-polar organic chemicals: (1) Field-measured 
BAFs; (2) predicted BAFs derived using a field-measured biota-sediment 
accumulation factor; (3) predicted BAFs derived by multiplying a 
laboratory-measured BCF by a food chain multiplier; and (4) predicted 
BAFs derived by multiplying a BCF calculated from the log Kow by a 
food-chain multiplier. The final Great Lakes Guidance developed BAFs 
for trophic levels three and four fish of the Great Lakes Basin. 
Respectively, the BAFs for mercury for trophic level 3 and 4 fish were: 
27,900 and 140,000.
    The BAF promulgated in the GLI was developed specifically for the 
Great Lakes System. It is uncertain whether the BAFs of 27,900 and 
140,000 are appropriate for use in California at this time; therefore, 
today's final rule does not use the GLI BAF in establishing human 
health criteria for mercury in California. The magnitude of the BAF for 
mercury in a given system depends on how much of the total mercury is 
present in the methylated form. Methylation rates vary widely from one 
water body to another for reasons that are not fully understood. 
Lacking the data, it is difficult to determine if the BAF used in the 
GLI represents the true potential for mercury to bioaccumulate in 
California surface waters. The true, average BAF for California could 
be higher or lower. For more information see EPA's Response to Comments 
document in the administrative record for this rule (specifically 
comments CTR-002-007(b) and CTR-016-007).
    EPA is developing a national BAF for mercury as part of revisions 
to its 304(a) criteria for human health; however, the BAF methodology 
that will be used is currently under evaluation as part of EPA's 
revisions to its National Human Health Methodology (see section F.3 
above). EPA applied a similar methodology in its Mercury Study Report 
to Congress (MSRC) to derive a BAF for methylmercury. The MSRC is 
available through NTIS (EPA-452/R-97-003). Although a BAF was derived 
in the MSRC, EPA does not intend to use this BAF for National 
application. EPA is engaged in a separate effort to incorporate 
additional mercury bioaccumulation data that was not considered in the 
MSRC, and to assess uncertainties with using a National BAF approach 
for mercury. Once the proposed revised human health methodology, 
including the BAF component, is finalized, EPA will revise its 304(a) 
criteria for mercury to reflect changes in the underlying methodology, 
recommendations contained in the MSRC, and recommendations in a 
National Academy of Science report on human health assessment of 
methylmercury. When EPA changes its 304(a) criteria recommendation for 
mercury, States and Tribes will be expected to review their water 
quality standards for mercury and make any revisions necessary to 
ensure their standards are scientifically defensible.
    New information may become available regarding the bioaccumulation

[[Page 31698]]

of mercury in certain water bodies in California. EPA supports the use 
of this information to develop site-specific criteria for mercury. 
Further, if a California water body is impaired due to mercury fish 
tissue or sediment contamination, loadings of mercury could contribute 
to or exacerbate the impairment. Therefore, one option regulatory 
authorities should consider is to include water quality-based effluent 
limits (WQBELs) in permits based on mass for discharges to the impaired 
water body. Such WQBELs must be derived from and comply with applicable 
State water quality standards (including both numeric and narrative 
criteria) and assure that the discharge does not cause or contribute to 
a violation of water quality standards.
d. Polychlorinated Biphenyls (PCBs) Criteria
    The NTR, as amended, calculated human health criteria for PCBs 
using a cancer potency factor of 7.7 per mg/kg-day from the Agency's 
IRIS. This cancer potency factor was derived from the Norback and 
Weltman (1985) study which looked at rats that were fed Aroclor 1260. 
The study used the linearized multistage model with a default cross-
species scaling factor (body weight ratio to the \2/3\ power). Although 
it is known that PCB mixtures vary greatly as to their potency in 
producing biological effects, for purposes of its carcinogenicity 
assessment, EPA considered Aroclor 1260 to be representative of all PCB 
mixtures. The Agency did not pool data from all available congener 
studies or generate a geometric mean from these studies, since the 
Norback and Weltman study was judged by EPA as acceptable, and not of 
marginal quality, in design or conduct as compared with other studies. 
Thereafter, the Institute for Evaluating Health Risks (IEHR, 1991) 
reviewed the pathological slides from the Norback and Weltman study, 
and concluded that some of the malignant liver tumors should have been 
interpreted as nonmalignant lesions, and that the cancer potency factor 
should be 5.1 per mg/kg-day as compared with EPA's 7.7 per mg/kg-day.
    The Agency's peer-reviewed reassessment of the cancer potency of 
PCBs published in a final report, PCBs: Cancer Dose-Response Assessment 
and Applications to Environmental Mixtures (EPA/600/P-96/001F), adopts 
a different approach that distinguishes among PCB mixtures by using 
information on environmental processes. (The report is included in the 
administrative record of today's rule.) The report considers all cancer 
studies (which used commercial mixtures only) to develop a range of 
cancer potency factors, then uses information on environmental 
processes to provide guidance on choosing an appropriate potency factor 
for representative classes of environmental mixtures and different 
pathways. The reassessment provides that, depending on the specific 
application, either central estimates or upper bounds can be 
appropriate. Central estimates describe a typical individual's risk, 
while upper bounds provide assurance (i.e., 95% confidence) that this 
risk is not likely to be underestimated if the underlying model is 
correct. Central estimates are used for comparing or ranking 
environmental hazards, while upper bounds provide information about the 
precision of the comparison or ranking. In the reassessment, the use of 
the upper bound values were found to increase cancer potency estimates 
by two or three-fold over those using central tendency. Upper bounds 
are useful for estimating risks or setting exposure-related standards 
to protect public health, and are used by EPA in quantitative cancer 
risk assessment. Thus, the cancer potency of PCB mixtures is determined 
using a tiered approach based on environmental exposure routes with 
upper-bound potency factors (using a body weight ratio to the \3/4\ 
power) ranging from 0.07 (lowest risk and persistence) to 2 (high risk 
and persistence) per mg/kg-day for average lifetime exposures to PCBs. 
It is noteworthy that bioaccumulated PCBs appear to be more toxic than 
commercial PCBs and appear to be more persistent in the body. For 
exposure through the food chain, risks can be higher than other 
exposures.
    EPA issued the final reassessment report on September 27, 1996, and 
updated IRIS to include the reassessment on October 1, 1996. EPA 
updated the human health criteria for PCBs in the National Toxics Rule 
on September 27, 1999. For today's rule, EPA derived the human health 
criteria for PCBs using a cancer potency factor of 2 per mg/kg-day, an 
upper bound potency factor reflecting high risk and persistence. This 
decision is based on recent multimedia studies indicating that the 
major pathway of exposure to persistent toxic substances such as PCBs 
is via dietary exposure (i.e., contaminated fish and shellfish 
consumption).
    Following is the calculation of the human health criterion (HHC) 
for organism and water consumption:
[GRAPHIC] [TIFF OMITTED] TR18MY00.013

Where:

RF = Risk Factor = 1 x 10-6
BW = Body Weight = 70 kg
q1* = Cancer slope factor = 2 per mg/kg-day
WC = Water Consumption = 2 l/day
FC = Fish and Shellfish Consumption = 0.0065 kg/day
BCF = Bioconcentration Factor = 31,200

the HHC (g/l) = 0.00017 g/l (rounded to two 
significant digits).
    Following is the calculation of the human health criterion for 
organism only consumption:
[GRAPHIC] [TIFF OMITTED] TR18MY00.014

Where:

RF = Risk Factor = 1 x 10-6
 BW = Body Weight = 70 kg
q1* = Cancer slope factor = 2 per mg/kg-day
FC = Total Fish and Shellfish Consumption per Day = 0.0065 kg/day
BCF = Bioconcentration Factor = 31,200

the HHC (g/l) = 0.00017 g/l (rounded to two 
significant digits).
    The criteria are both equal to 0.00017 g/l and apply to 
total PCBs. See PCBs: Cancer Dose Response Assessment and Application 
to Environmental Mixtures (EPA/600/9-96-001F). For a discussion of the 
body weight, water consumption, and fish and shellfish consumption 
factors, see the Human Health Guidelines. For a discussion of the BCF, 
see the 304(a) criteria guidance document for PCBs (included in the 
administrative record for today's rule).
e. Excluded Section 304(a) Human Health Criteria
    As is the case in the NTR, as amended, today's rule does not 
promulgate criteria for certain priority pollutants for which CWA 
section 304(a) criteria guidance exists because those criteria were not 
based on toxicity to humans or aquatic organisms. The basis for those 
particular criteria is organoleptic effects (e.g., taste and odor) 
which would make water and edible aquatic life unpalatable but not 
toxic. Because the basis for this rule is to protect the public health 
and aquatic life from toxicity consistent with the language and intent 
in CWA section 303(c)(2)(B), EPA is promulgating criteria only for 
those priority toxic pollutants whose criteria recommendations are 
based on toxicity. The CWA section 304(a) human health criteria based 
on organoleptic effects for zinc and 3-methyl-4-chlorophenol are 
excluded for this reason. See the 1992 NTR discussion at 57 FR 60864.

[[Page 31699]]

f. Cancer Risk Level
    EPA's CWA section 304(a) criteria guidance documents for priority 
toxic pollutants that are based on carcinogenicity present 
concentrations for upper bound risk levels of 1 excess cancer case per 
100,000 people (10-5), per 1,000,000 people 
(10-6), and per 10,000,000 people (10-7). 
However, the criteria documents do not recommend a particular risk 
level as EPA policy.
    As part of the proposed rule, EPA requested and received comment on 
the adoption of a 10 -5 risk level for carcinogenic 
pollutants. The effect of a 10-5 risk level would have been 
to increase (i.e., make less stringent) carcinogenic pollutant criteria 
values (noted in the matrix by footnote c) that are not already 
promulgated in the NTR, by one order of magnitude. For example, the 
organism-only criterion for gamma BHC (pollutant number 105 in the 
matrix) is 0.013 g/l; the criterion based on a 10-5 
risk level would have been 0.13 g/l. EPA received several 
comments that indicated a preference for a higher (10-4 and 
10-5) risk level for effluent dependent waters or other 
types of special circumstances.
    In today's rule, EPA is promulgating criteria that protect the 
general population at an incremental cancer risk level of one in a 
million (10-6) for all priority toxic pollutants regulated 
as carcinogens, consistent with the criteria promulgated in the NTR for 
the State of California. Standards adopted by the State contained in 
the Enclosed Bays and Estuaries Plan (EBEP), and the Inland Surface 
Waters Plan (ISWP), partially approved by EPA on November 6, 1991, and 
the Ocean Plan approved by EPA on June 28, 1990, contained a risk level 
of 10-6 for most carcinogens. The State has historically 
protected at a 10-6 risk level for carcinogenic pollutants.
    EPA, in its recent human health methodology revisions, proposed 
acceptable lifetime cancer risk for the general population in the range 
of 10-5 to 10-6. EPA also proposed that States 
and Tribes ensure the most highly exposed populations do not exceed a 
10-4 risk level. However, EPA's draft methodology revisions 
also stated that it will derive 304(a) criteria at a 10-6 
risk level, which the Agency believes reflects the appropriate risk for 
the general population and which applies a risk management policy which 
ensures protection for all exposed population groups. (Draft Water 
Quality Criteria Methodology: Human Health, EPA 822-Z-98-001, August 
1998, Appendix II, page 72).
    Subpopulations within a State may exist, such as recreational and 
subsistence anglers, who as a result of greater exposure to a 
contaminant are at greater risk than the standard 70 kilogram person 
eating 6.5 grams per day of fish and shellfish and drinking 2.0 liters 
per day of drinking water with pollutant levels meeting the water 
quality criteria. EPA acknowledges that at any given risk level for the 
general population, those segments of the population that are more 
highly exposed face a higher relative risk. For example, if fish are 
contaminated at a level permitted by criteria derived on the basis of a 
risk level of 10-6, individuals consuming up to 10 times the 
assumed fish consumption rate would still be protected at a 
10-5 risk level. Similarly, individuals consuming 100 times 
the general population rate would be protected at a 10-4 
risk level. EPA, therefore, believes that derivation of criteria at the 
10-6 risk level is a reasonable risk management decision 
protective of designated uses under the CWA. While outside the scope of 
this rule, EPA notes that States and Tribes, however, have the 
discretion to adopt water quality criteria that result in a higher risk 
level (e.g., 10-5). EPA expects to approve such criteria if 
the State or Tribe has identified the most highly exposed subpopulation 
within the State or Tribe, demonstrates the chosen risk level is 
adequately protective of the most highly exposed subpopulation, and has 
completed all necessary public participation.
    This demonstration has not happened in California. Further, the 
information that is available on highly exposed subpopulations in 
California supports the need to protect the general population at the 
10-6 level. California has cited the Santa Monica Bay 
Seafood Consumption Study as providing the best available data set for 
estimating consumption of sport fish and shellfish in California for 
both marine or freshwater sources (Chemicals in Fish Report No. 1: 
Consumption of Fish and Shellfish in California and the United States, 
Final Draft Report, July 1997). Consumption rates of sport fish and 
shellfish of 21g/day, 50 g/day, 107 g/day, and 161 g/day for the 
median, mean, 90th, and 95th percentile rates, respectively, were 
determined from this study. Additional consumption of commercial 
species in the range of approximately 8 to 42 g/day would further 
increase these values. Clearly the consumption rates for the most 
highly exposed subpopulation within the State exceeds 10 times the 6.5 
g/day rates used in the CTR. Therefore, use of a risk level of 
10-5 for the general population would not be sufficient to 
protect the most highly exposed population in California at a 
10-4 risk level. On the other hand, even the most highly 
exposed subpopulations cited in the California study do not have 
consumption rates approaching 100 times the 6.5 g/day rates used in the 
CTR. The use of the 10-6 risk level to protect average level 
consumers does not subject these subpopulations to risk levels as high 
as 10-4.
    EPA believes its decision to establish a 10-6 risk level 
for the CTR is also consistent with EPA's policy in the NTR to select 
the risk level that reflect the policies or preferences of CWA programs 
in the affected States. California adopted standards for priority toxic 
pollutants for its ocean waters in 1990 using a 10-6 risk 
level to protect human health (California Ocean Plan, 1990). In April 
1991, and again in November 1992, California adopted standards for its 
inland surface waters and enclosed bays and estuaries in its Inland 
Surface Waters Plan (ISWP) and its Enclosed Bays and Estuaries Plan 
(EBEP) using a 10-6 risk level. To be consistent with the 
State's water quality standards, EPA used a 10-6 risk level 
for California in the NTR at 57 FR 60867. The State has continued using 
a 10-6 risk level to protect human health for its standards 
that were not withdrawn with the ISWP and EBEP. The most recent 
expression of risk level preference is contained in the Draft 
Functional Equivalent Document, Amendment of the Water Quality Control 
Plan for Ocean Waters of California, October 1998, where the State 
recommended maintaining a consistent risk level of 10-6 for 
the human health standards that it was proposing to revise.
    EPA received several comments requesting a 10-5 risk 
level based on the risk level chosen for the Great Lakes Water Quality 
Guidance (the Guidance). There are several differences between the 
guidelines for the derivation of human health criteria contained in the 
Guidance and the California Toxics Rule (CTR) that make a 
10-5 risk factor appropriate for the Guidance, but not for 
the CTR. These differences result in criteria developed using the 
10-5 risk factor in the Guidance being at least as stringent 
as criteria derived under the CTR using a 10-6 risk factor. 
The relevant aspects of the Guidance include:
     Use of fish consumption rates that are considerably higher 
than fish consumption rates for the CTR.
     Use of bioaccumulation factors rather than 
bioconcentration factors in

[[Page 31700]]

estimating exposure, considerably increasing the dose of carcinogens to 
sensitive subgroups.
     Consideration of additivity of effects of mixtures for 
both carcinogenic and noncarcinogenic pollutants.
    This combination of factors increase the calculated carcinogenic 
risk substantially under the Guidance (the combination would generally 
be more than one order of magnitude), making a lower overall risk 
factor acceptable. The Guidance risk factor provides, in fact, criteria 
with at least the same level of protection against carcinogens as 
criteria derived with a higher risk factor using the CTR. A lower risk 
factor for the CTR would not be appropriate absent concomitant changes 
in the derivation procedures that provide equivalent risk protection.

G. Description of Final Rule

1. Scope

    Paragraph (a) in 40 CFR 131.38, entitled ``Scope,'' states that 
this rule is a promulgation of criteria for priority toxic pollutants 
in the State of California for inland surface waters, enclosed bays, 
and estuaries. Paragraph (a) in 40 CFR 131.38 also states that this 
rule contains an authorizing compliance schedule provision.
    2. EPA Criteria for Priority Toxic Pollutants
    EPA's criteria for California are presented in tabular form at 40 
CFR 131.38. For ease of presentation, the table that appears combines 
water quality criteria promulgated in the NTR, as amended, that are 
outside the scope of this rulemaking, with the criteria that are within 
the scope of today's rule. This is intended to help readers determine 
applicable water quality criteria for the State of California. The 
table contains footnotes for clarification.
    Paragraph (b) in 40 CFR 131.38 presents a matrix of the applicable 
EPA aquatic life and/or human health criteria for priority toxic 
pollutants in California. Section 303(c)(2)(B) of the CWA addresses 
only pollutants listed as ``toxic'' pursuant to section 307(a) of the 
CWA for which EPA has developed section 304(a) criteria guidance. As 
discussed earlier in this preamble, the section 307(a) list of toxics 
contains 65 compounds and families of compounds, which potentially 
include thousands of specific compounds. Of these, the Agency 
identified a list of 126 ``priority toxic pollutants'' to implement the 
CWA (see 40 CFR 131.36(b)). Reference in this rule to priority toxic 
pollutants, toxic pollutants, or toxics refers to the 126 priority 
toxic pollutants.
    EPA has not developed both aquatic life and human health CWA 
section 304(a) criterion guidance for all of the priority toxic 
pollutants. The matrix in 40 CFR 131.38(b) contains human health 
criteria in Column D for 92 priority toxic pollutants which are divided 
into Column 1: criteria for water consumption (i.e., 2.0 liters per 
day) and aquatic organism consumption (i.e., 6.5 grams per day of 
aquatic organisms); and Column 2: criteria for aquatic organism 
consumption only. The term aquatic organism includes fish and shellfish 
such as shrimp, clams, oysters and mussels. One reason the total number 
of priority toxic pollutants with criteria today differs from the total 
number of priority toxic pollutants contained in earlier published CWA 
section 304(a) criteria guidance is because EPA has developed and is 
promulgating chromium criteria for two valence states with respect to 
aquatic life criteria. Thus, although chromium is a single priority 
toxic pollutant, there are two criteria for chromium for aquatic life 
protection. See pollutant 5 in today's rule at 40 CFR 131.38(b). 
Another reason is that EPA is promulgating human health criteria for 
nine priority pollutants for which health-based national criteria have 
been calculated based on information obtained from EPA's IRIS database 
(EPA provided notice of these nine criteria in the NTR for inclusion in 
future State triennial reviews. See 57 FR 60848, 60890).
    The matrix contains aquatic life criteria for 23 priority 
pollutants. These are divided into freshwater criteria (Column B) and 
saltwater criteria (Column C). These columns are further divided into 
acute and chronic criteria. The aquatic life criteria are considered by 
EPA to be protective when applied under the conditions described in the 
section 304(a) criteria documents and in the TSD. For example, water 
body uses should be protected if the criteria are not exceeded, on 
average, once every three year period. It should be noted that the 
criteria maximum concentrations (the acute criteria) are short-term 
concentrations and that the criteria continuous concentrations (the 
chronic criteria) are four-day averages. It should also be noted that 
for certain metals, the actual criteria are equations which are 
included as footnotes to the matrix. The toxicity of these metals is 
water hardness dependent and may be adjusted. The values shown in the 
table are illustrative only, based on a hardness expressed as calcium 
carbonate of 100 mg/l. Finally, the criterion for pentachlorophenol is 
pH dependent. The equation is the actual criterion and is included as a 
footnote. The value shown in the matrix is for a pH of 7.8. Several of 
the freshwater aquatic life criteria are incorporated into the matrix 
in the format used in the 1980 criteria methodology which uses a final 
acute value instead of a continuous maximum concentration. This 
distinction is noted in footnote g of the table.
    The final rule at 40 CFR 131.38(c) establishes the applicability of 
the criteria to the State of California. 40 CFR 131.38(d) is described 
later in Section F, of this preamble. EPA has included in this rule 
provisions necessary to implement numeric criteria in a way that 
maintains the level of protection intended. These provisions are 
included in 40 CFR 131.38(c) of today's rule. For example, in order to 
do steady state waste load allocation analyses, most States have low 
flow values for streams and rivers which establish flow rates for 
various purposes. These low flow values become design flows for sizing 
treatment plants and developing water quality-based effluent limits 
and/or TMDLs. Historically, these design flows were selected for the 
purposes of waste load allocation analyses which focused on instream 
dissolved oxygen concentrations and protection of aquatic life. With 
the publication of the 1985 TSD, EPA introduced hydrologically and 
biologically based analyses for the protection of aquatic life and 
human health. (These concepts have been expanded subsequently in EPA's 
Technical Guidance Manual for Performing Wasteload Allocations, Book 6, 
Design Conditions, U.S. EPA, 1986. These analyses are included in 
Appendix D of the revised TSD. The discussion here is greatly 
simplified and is provided to support EPA's decision to promulgate 
design flows for instream flows and thereby maintain the adequacy of 
the criteria for priority toxic pollutants.) EPA recommended either of 
two methods for calculating acceptable low flows, the traditional 
hydrologic method developed by the U.S. Geological Survey or a 
biological based method developed by EPA. Other methods for evaluating 
the instream flow record may be available; use of these methods may 
result in TMDLs and/or water quality-based effluent limitations which 
adequately protect human health and/or aquatic life. The results of 
either of these two methods, or an equally protective alternative 
method, may be used.
    The State of California may adopt specific design flows for streams 
and rivers to protect designated uses against the effects of toxics. 
EPA believes it is

[[Page 31701]]

important to specify design flows in today's rule so that, in the 
absence of state design flows, the criteria promulgated today would be 
implemented appropriately. The TSD also recommends the use of three 
dynamic models to perform wasteload allocations. Dynamic wasteload 
models do not generally use specific steady state design flows but 
accomplish the same effect by factoring in the probability of 
occurrence of stream flows based on the historical flow record.
    The low flows specified in the rule explicitly contain duration and 
frequency of occurrence which represent certain probabilities of 
occurrence. Likewise, the criteria for priority toxic pollutants are 
defined with duration and frequency components. Dynamic modeling 
techniques explicitly predict the effects of variability in receiving 
water, effluent flow, and pollution variation. Dynamic modeling 
techniques, as described in the TSD, allow for calculating wasteload 
allocations that meet the criteria for priority toxic pollutants 
without using a single, worst-case concentration based on a critical 
condition. Either dynamic modeling or steady state modeling can be used 
to implement the criteria promulgated today. For simplicity, only 
steady state conditions are discussed here. Clearly, if the criteria 
were implemented using design flows that are too high, the resulting 
toxic controls would not be adequate, because the resulting ambient 
concentrations would exceed EPA's criteria.
    In the case of aquatic life, assuming exceedences occur more 
frequently than once in three years on the average, exceedences would 
result in diminished vitality of stream ecosystems characterized by the 
loss of desired species. Numeric water quality criteria should apply at 
all flows that are equal to or greater than flows specified below. The 
low flow values are:

------------------------------------------------------------------------
             Type of criteria                        Design flow
------------------------------------------------------------------------
Acute Aquatic Life (CMC)..................  1 Q 10 or 1 B 3
Chronic Aquatic Life (CCC)................  7 Q 10 or 4 B 3
Human Health..............................  harmonic mean flow
------------------------------------------------------------------------

Where:

1 Q 10 is the lowest one day flow with an average recurrence frequency 
of once in 10 years determined hydrologically;
1 B 3 is biologically based and indicates an allowable exceedence of 
once every 3 years. It is determined by EPA's computerized method 
(DFLOW model);
7 Q 10 is the lowest average 7 consecutive day low flow with an average 
recurrence frequency of once in 10 years determined hydrologically;
4 B 3 is biologically based and indicates an allowable exceedences for 
4 consecutive days once every 3 years. It is determined by EPA's 
computerized method (DFLOW model);

    EPA is requiring that the harmonic mean flow be applied with human 
health criteria. The harmonic mean is a standard calculated statistical 
value. EPA's model for human health effects assumes that such effects 
occur because of a long-term exposure to low concentration of a toxic 
pollutant, for example, two liters of water per day for seventy years. 
To estimate the concentrations of the toxic pollutant in those two 
liters per day by withdrawal from streams with a high daily variation 
in flow, EPA believes the harmonic mean flow is the correct statistic 
to use in computing such design flows rather than other averaging 
techniques. (For a description of harmonic means see ``Design Stream 
Flows Based on Harmonic Means,'' Lewis A. Rossman, Jr. of Hydraulics 
Engineering, Vol. 116, No. 7, July, 1990.)
    All waters (including lakes, estuaries, and marine waters), whether 
or not suitable for such hydrologic calculations, are subject to the 
criteria promulgated today. Such criteria will need to be attained at 
the end of the discharge pipe, unless the State authorizes a mixing 
zone. Where the State plans to authorize a mixing zone, the criteria 
would apply at the locations allowed by the mixing zone. For example, 
the chronic criteria (CCC) would apply at the defined boundary of the 
chronic mixing zone. Discussion of and guidance on these factors are 
included in the revised TSD in Chapter 4.
    EPA is aware that the criteria promulgated today for some of the 
priority toxic pollutants are at concentrations less than EPA's current 
analytical detection limits. Analytical detection limits have never 
been an acceptable basis for setting water quality criteria since they 
are not related to actual environmental impacts. The environmental 
impact of a pollutant is based on a scientific determination, not a 
measuring technique which is subject to change. Setting the criteria at 
levels that reflect adequate protection tends to be a forcing mechanism 
to improve analytical detection methods. See 1985 Guidelines, page 21. 
As the methods improve, limits based on the actual criteria necessary 
to protect aquatic life and human health become measurable. The Agency 
does not believe it is appropriate to promulgate criteria that are not 
sufficiently protective. EPA discusses this issue further in its 
Response to Comment Document for today's final rule.
    EPA does believe, however, that the use of analytical detection 
limits are appropriate for assessing compliance with National Pollutant 
Discharge Elimination System (NPDES) permit limits. This view of the 
role of detection limits was first articulated in guidance for 
translating dioxin criteria into NPDES permit limits. See ``Strategy 
for the Regulation of Discharges of PHDDs and PHDFs from Pulp and Paper 
Mills to Waters of the U.S.'' Memorandum from the Assistant 
Administrator for Water to the Regional Water Management Division 
Directors, May 21, 1990. This guidance presented a model for addressing 
toxic pollutants which have criteria less than current detection 
limits. EPA, in more recent guidance, recommends the use of the 
``minimum level'' or ML for reporting sample results to assess 
compliance with WQBELs (TSD page 111). The ML, also called the 
``quantification level,'' is the level at which the entire analytical 
system gives recognizable mass spectra and acceptable calibration 
points, i.e., the point at which the method can reliably quantify the 
amount of pollutant in the sample. States can use their own procedures 
to average and otherwise account for monitoring data, e.g., quantifying 
results below the ML. These results can then be used to assess 
compliance with WQBELs. (See 40 CFR part 132, Appendix F, Procedure 
8.B.) This approach is applicable to priority toxic pollutants with 
criteria less than current detection limits. EPA's guidance explains 
that standard analytical methods may be used for purposes of assessing 
compliance with permit limits, but not for purposes of establishing 
water quality criteria or permit limits. Under the CWA, analytical 
methods are appropriately used in connection with NPDES permit limit 
compliance assessments. Because of the function of water quality 
criteria, EPA has not considered the sensitivity of analytical methods 
in deriving the criteria promulgated today.
    EPA has promulgated 40 CFR 131.38(c)(3) to determine when 
freshwater or saltwater aquatic life criteria apply. This provision 
incorporates a time parameter to better define the critical condition. 
The structure of the paragraph is to establish

[[Page 31702]]

applicable rules and to allow for site-specific exceptions where the 
rules are not consistent with actual field conditions. Because a 
distinct separation generally does not exist between freshwater and 
saltwater aquatic communities, EPA is establishing the following: (1) 
The freshwater criteria apply at salinities of 1 part per thousand and 
below at locations where this occurs 95% or more of the time; (2) 
saltwater criteria apply at salinities of 10 parts per thousand and 
above at locations where this occurs 95% more of the time; and (3) at 
salinities between 1 and 10 parts per thousand the more stringent of 
the two apply unless EPA approves the application of the freshwater or 
saltwater criteria based on an appropriate biological assessment. The 
percentiles included here were selected to minimize the chance of 
overlap, that is, one site meeting both criteria. Determination of 
these percentiles can be done by any reasonable means such as 
interpolation between points with measured data or by the application 
of calibrated and verified mathematical models (or hydraulic models). 
It is not EPA's intent to require actual data collection at particular 
locations.
    In the brackish water transition zones of estuaries with varying 
salinities, there generally will be a mix of freshwater and saltwater 
species. Generally, therefore, it is reasonable for the more stringent 
of the freshwater or saltwater criteria to apply. In evaluating 
appropriate data supporting the alternative set of criteria, EPA will 
focus on the species composition as its preferred method. This 
assignment of criteria for fresh, brackish and salt waters was 
developed in consultation with EPA's research laboratories at Duluth, 
Minnesota and Narragansett, Rhode Island. The Agency believes such an 
approach is consistent with field experience.
    Paragraph (d) in 40 CFR 131.38 lists the designated water and use 
classifications for which the criteria apply. The criteria are applied 
to the beneficial use designations adopted by the State of California; 
EPA has not promulgated any new use classifications in this rule.
    Exceedences Frequency: In a water quality criterion for aquatic 
life, EPA recommends an allowable frequency for excursions of the 
criteria. See 1985 Guidelines, pages 11-13. This allowable frequency 
provides an appropriate period of time during which the aquatic 
community can recover from the effect of an excursion and then function 
normally for a period of time before the next excursion. An excursion 
is defined as an occurrence of when the average concentration over the 
duration of the averaging period is above the CCC or the CMC. As 
ecological communities are naturally subjected to a series of stresses, 
the allowable frequency of pollutant stress may be set at a value that 
does not significantly increase the frequency or severity of all 
stresses combined. See also TSD, Appendix D. In addition, providing an 
allowable frequency for exceeding the criterion recognizes that it is 
not generally possible to assure that criteria are never exceeded. 
(TSD, page 36.)
    Based on the available data, today's rule requires that the acute 
criterion for a pollutant be exceeded no more than once in three years 
on the average. EPA is also requiring that the chronic criterion for a 
pollutant be exceeded no more than once in three years on the average. 
EPA acknowledges that States may develop allowable frequencies that 
differ from these allowable frequencies, so long as they are 
scientifically supportable, but believes that these allowable 
frequencies are protective of the designated uses where EPA is 
promulgating criteria.
    The use of aquatic life criteria for developing water quality-based 
effluent limits in permits requires the permitting official to use an 
appropriate wasteload allocation model. (TSD, Appendix D-6.) As 
discussed above, there are generally two methods for determining design 
flows, the hydrologically-based method and the biologically-based 
method.
    The biologically-based method directly uses the averaging periods 
and frequencies specified in the aquatic life criteria for determining 
design flows. (TSD, Appendix. D-8.) Because the biologically-based 
method calculates the design flow directly from the duration and 
allowable frequency, it most accurately provides the allowed number of 
excursions. The hydrologically based method applies the CMC at a design 
flow equal to or equivalent to the 1Q10 design flow (i.e., the lowest 
one-day flow with an average recurrence frequency of once in ten 
years), and applies the CCC at the 7Q10 design flow (i.e., the lowest 
average seven consecutive day flow with a recurrence frequency of once 
in ten years).
    EPA established a three year allowable frequency in the NTR. In 
settlement of the litigation on the NTR, EPA stated that it was in the 
midst of conducting, sponsoring, or planning research aimed at 
addressing scientific issues related to the basis for and application 
of water quality criteria and mentioned the issue of allowable 
frequency. See Partial Settlement Agreement in American Forest and 
Paper Ass'n, Inc. et al. v. U.S. EPA (Consolidated Case No. 93-0694 
(RMU) D.D.C. To that end, EPA is reevaluating issues raised about 
allowable frequency as part of its work in revising the 1985 
Guidelines.
    EPA recognizes that additional data concerning (a) the probable 
frequency of lethal events for an assemblage of taxa covering a range 
of sensitivities to pollutants, (b) the probable frequency of sublethal 
effects for such taxa, (c) the differing effects of lethal and 
sublethal events in reducing populations of such taxa, and (d) the time 
needed to replace organisms lost as a result of toxicity, may lead to 
further refinement of the allowable frequency value. EPA has not yet 
completed this work. Until this work is complete, EPA believes that 
where EPA promulgates criteria, the three year allowable frequency 
represents a value in the reasonable range for this parameter.

3. Implementation

    Once the applicable designated uses and water quality criteria for 
a water body are determined, under the National Pollutant Discharge 
Elimination System (NPDES) program discharges to the water body must be 
characterized and the permitting authority must determine the need for 
permit limits. If a discharge causes, has the reasonable potential to 
cause, or contributes to an excursion of a numeric or narrative water 
quality criteria, the permitting authority must develop permit limits 
as necessary to meet water quality standards. These permit limits are 
water quality-based effluent limitations or WQBELs. The terms 
``cause,'' ``reasonable potential to cause,'' and ``contribute to'' are 
the terms in the NPDES regulations for conditions under which water 
quality-based permit limits are required. See 40 CFR 122.44(d)(1).
    Since the publication of the proposed CTR, the State of California 
adopted procedures which detail how water quality criteria will be 
implemented through NPDES permits, waste discharge requirements, and 
other regulatory approaches. These procedures entitled, Policy for 
Implementation of Toxics Standards for Inland Surface Waters, Enclosed 
Bays, and Estuaries of California were adopted on March 2, 2000. Once 
these procedures are submitted for review under CWA section 303(c), EPA 
will review them as they relate to water quality standards, and approve 
or disapprove them.
    Several commenters understood the language in the preamble to the 
proposed rule regarding implementation

[[Page 31703]]

to mean that site-specific criteria, variances, and other actions would 
be prohibited or severely limited by the CTR. Site-specific criteria, 
variances and other actions modifying criteria are neither prohibited 
nor limited by the CTR. The State, if it so chooses, still can make 
these changes to its water quality standards, subject to EPA approval. 
However, with this Federal rule in effect, the State cannot implement 
any modifications that are less stringent than the CTR without an 
amendment to the CTR to reflect these modifications. EPA will make 
every effort to expeditiously accommodate Federal rulemaking of 
appropriate modifications to California's water quality standards. In 
the preamble to the proposed CTR, and here today, EPA is emphasizing 
that these efforts to amend the CTR on a case-by-case basis will 
generally increase the time before a modification can be implemented.

4. Wet Weather Flows

    EPA has for a longtime maintained that CWA section 301(b)(1)(C) 
applies to NPDES permits for discharges from municipal separate storm 
sewer systems. Recently, the U.S. Court of Appeals for the Ninth 
Circuit upheld NPDES permits issued by EPA for five Arizona municipal 
separate storm sewer systems and addressed this issue specifically. 
Defenders of Wildlife, et al. v. Browner, No. 98-71080 (9th Cir., 
October 1999). The Court held that the CWA does not require ``strict 
compliance'' with State water quality standards for municipal storm 
sewer permits under section 301(b)(1)(C), but that at the same time, 
the CWA does give EPA discretion to incorporate appropriate water 
quality-based effluent limitations under another provision, CWA section 
402(p)(3)(B)(iii).
    The Court based its decision on the structure of section 402(p)(3), 
which contains distinct language for discharges of industrial storm 
water and municipal storm water. In section 402(p)(3)(A), Congress 
requires that ``dischargers associated with industrial activity shall 
meet all applicable provisions of [section 402] and section [301].'' 33 
U.S.C. section 1342(p)(3)(A). The Court noted, therefore, that by 
incorporation, industrial storm water discharges need to achieve ``any 
more stringent limitation, including those necessary to meet water 
quality standards * * *'' The Court explained that industrial storm 
water discharges ``must comply strictly with State water quality 
standards'' but that Congress chose not to include a similar provision 
for municipal storm sewer discharges, including instead a requirement 
for controls to reduce pollutants to the maximum extent practicable or 
MEP standard in section 402(p)(3)(B). Reading the two related sections 
together, the Court concluded that section 402(p)(3)(B)(iii) does not 
require ``strict compliance'' by municipal storm sewer discharges 
according to section 301(b)(1)(C). At the same time, however, the Court 
found that the language in CWA section 402(p)(3)(B)(iii) which states 
that permits for discharges from municipal storm sewers shall require 
``such other provisions as the Administrator of the state determines 
appropriate for the control of such pollutants'' provides EPA with 
discretion to incorporate provisions lending to ultimate compliance 
with water quality standards.
    EPA believes that compliance with water quality standards through 
the use of Best Management Practices (BMPs) is appropriate. EPA 
articulated its position on the use of BMPs in storm water permits in 
the policy memorandum entitled, ``Interim Permitting Approach for Water 
Quality-Based Effluent Limitations In Storm Water Permits'' which was 
signed by the Assistant Administrator for Water, Robert Perciasepe on 
August 1, 1996 (61 FR 43761, August 9, 1996). A copy of this memorandum 
is contained in the administrative record for today's rule. The policy 
affirms the use of BMPs as a means to attain water quality standards in 
municipal storm water permits, and embraces BMPs as an interim 
permitting approach.
    The interim permitting approach uses BMPs in first-round storm 
water permits, and expanded or better-tailored BMPs in subsequent 
permits, where necessary, to provide for the attainment of water 
quality standards. In cases where adequate information exists to 
develop more specific conditions or limitations to meet water quality 
standards, these conditions or limitations are to be incorporated into 
storm water permits, as necessary and appropriate.
    This interim permitting approach, however, only applies to EPA. EPA 
encourages the State to adopt a similar policy for municipal storm 
water permits. This interim permitting approach provides time, where 
necessary, to more fully assess the range of issues and possible 
options for the control of storm water discharges for the protection of 
water quality. More information on this issue is included in the 
response to comment document in response to specific storm water issues 
raised by commenters.

5. Schedules of Compliance

    A compliance schedule refers to an enforceable sequence of interim 
requirements in a permit leading to ultimate compliance with water 
quality-based effluent limitations or WQBELs in accordance with the 
CWA. The authorizing compliance schedule provision authorizes, but does 
not require, the permit issuing authority in the State of California to 
include such compliance schedules in permits under appropriate 
circumstances. The State of California is authorized to administer the 
National Pollutant Discharge Elimination System (NPDES) program and may 
exercise its discretion when deciding if a compliance schedule is 
justified because of the technical or financial (or other) 
infeasibility of immediate compliance. An authorizing compliance 
schedule provision is included in today's rule because of the potential 
for existing dischargers to have new or more stringent effluent 
limitations for which immediate compliance would not be possible or 
practicable.
    New and Existing Dischargers: The provision allows compliance 
schedules only for an ``existing discharger'' which is defined as any 
discharger which is not a ``new California discharger.'' A ``new 
California discharger'' includes ``any building, structure, facility, 
or installation from which there is, or may be, a `discharge of 
pollutants', the construction of which commences after the effective 
date of this regulation.'' These definitions are modeled after the 
existing 40 CFR 122.2 definitions for parallel terms, but with a cut-
off date modified to reflect this rule. Only ``new California 
dischargers'' are required to comply immediately upon commencement of 
discharge with effluent limitations derived from the criteria in this 
rule. For ``existing dischargers'' whose permits are reissued or 
modified to contain new or more stringent limitations based upon 
certain water quality requirements, the permit could allow up to five 
years, or up to the length of a permit, to comply with such 
limitations. The provision applies to new or more stringent effluent 
limitations based on the criteria in this EPA rule.
    EPA has included ``increasing dischargers'' within the category of 
``existing dischargers'' since ``increasing dischargers'' are existing 
facilities with a change--an increase--in their discharge. Such 
facilities may include those with seasonal variations. ``Increasing 
dischargers'' will already have treatment systems in place for their 
current discharge, thus, they have less

[[Page 31704]]

opportunity than a new discharger does to design and build a new 
treatment system which will meet new water quality-based requirements 
for their changed discharge. Allowing existing facilities with an 
increasing discharge a compliance schedule will avoid placing the 
discharger at a competitive disadvantage vis-a-vis other existing 
dischargers who are eligible for compliance schedules.
    Today's rule does not prohibit the use of a short-term ``shake down 
period'' for new California dischargers as is provided for new sources 
or new dischargers in 40 CFR 122.29(d)(4). These regulations require 
that the owner or operator of (1) a new source; (2) a new discharger 
(as defined in 40 CFR 122.2) which commenced discharge after August 13, 
1979; or (3) a recommencing discharger shall install and implement all 
pollution control equipment to meet the conditions of the permit before 
discharging. The facility must also meet all permit conditions in the 
shortest feasible time (not to exceed 90 days). This shake-down period 
is not a compliance schedule. This approach may be used to address 
violations which may occur during a new facility's start-up, especially 
where permit limits are water quality-based and biological treatment is 
involved.
    The burden of proof to show the necessity of a compliance schedule 
is on the discharger, and the discharger must request approval from the 
permit issuing authority for a schedule of compliance. The discharger 
should submit a description of the minimum required actions or 
evaluations that must be undertaken in order to comply with the new or 
more restrictive discharge limits. Dates of completion for the required 
actions or evaluations should be included, and the proposed schedule 
should reflect the shortest practicable time to complete all minimum 
required actions.
    Duration of Compliance Schedules: Today's rule provides that 
compliance schedules may provide for up to five years to meet new or 
more stringent effluent limitations in those limited circumstances 
where the permittee can demonstrate to the permit authority that an 
extended schedule is warranted. EPA's regulations at 122.47 require 
compliance with standards as soon as possible. This means that permit 
authorities should not allow compliance schedules where the permittee 
fails to demonstrate their necessity. This provision should not be 
considered a default compliance schedule duration for existing 
facilities.
    In instances where dischargers wish to conduct toxicological 
studies, analyze results, and adopt and implement new or revised water 
quality-based effluent limitations, EPA believes that five years is 
sufficient time within which to complete this process. See the preamble 
to the proposed rule.
    Under this rule, where a schedule of compliance exceeds one year, 
interim requirements are to be specified and interim progress reports 
are to be submitted at least annually to the permit issuing authority, 
in at least one-year time intervals.
    The rule allows all compliance schedules to extend up to a maximum 
duration of five years, which is the maximum term of any NPDES permit. 
See 40 CFR 122.46. The discharger's opportunity to obtain a compliance 
schedule occurs when the existing permit for that discharge is issued, 
reissued or modified to contain more stringent limits based on the 
water quality criteria in today's rule. Such compliance schedules, 
however, cannot be extended to any indefinite point of time in the 
future because the compliance schedule provision in this rule will 
sunset on May 18, 2005. The sunset applies to the authorizing provision 
in today's rule (40 CFR 131.38(e)), not to individual schedules of 
compliance included in specific NPDES permits. Delays in reissuing 
expired permits (including those which continue in effect under 
applicable NPDES regulations) cannot indefinitely extend the period of 
time during which a compliance schedule is in effect. This would occur 
where the permit authority includes the single maximum five-year 
compliance schedule in a permit that is reissued just before the 
compliance schedule provision sunsets (having been previously issued 
without WQBELS using the rule's criteria on the eve of the effective 
date of this rule). Instead, the effect of the sunset provision is to 
limit the longest time period for compliance to ten years after the 
effective date of this rule.
    EPA recognizes that where a permit is modified during the permit 
term, and the permittee needs the full five years to comply, the five-
year schedule may extend beyond the term of the modified permit. In 
such cases, the rule allows for the modified permit to contain a 
compliance schedule with an interim limit by the end of the permit 
term. When the permit is reissued, the permit authority may extend the 
compliance schedule in the next permit, provided that, taking into 
account the amount of time allowed under the previous permit, the 
entire compliance schedule contained in the permit shall not exceed 
five years. Final permit limits and compliance dates will be included 
in the record for the permit. Final compliance dates must occur within 
five years from the date of permit issuance, reissuance, or 
modification, unless additional or less time is provided for by law.
    EPA would prefer that the State adopt an authorizing compliance 
schedule provision but recognizes that the State may not be able to 
complete this action for some time after promulgation of the CTR. Thus, 
EPA has chosen to promulgate the rule with a sunset provision which 
states that the authorizing compliance schedule provision will cease or 
sunset on May 18, 2005. However, if the State Board adopts, and EPA 
approves, a statewide authorizing compliance schedule provision 
significantly prior to May 18, 2005, EPA will act to stay the 
authorizing compliance schedule provision in today's rule. 
Additionally, if a Regional Board adopts, and the State Board adopts 
and EPA approves, a Regional Board authorizing compliance schedule 
provision, EPA will act to stay today's provision for the appropriate 
or corresponding geographic region in California. At that time, the 
State Board's or Regional Board's authorizing compliance schedule 
provision will govern the ability of the State regulatory entity to 
allow a discharger to include a compliance schedule in a discharger's 
NPDES permit.
    Antibacksliding: EPA wishes to address the potential concern over 
antibacksliding where revised permit limits based on new information 
are the result of the completion of additional studies. The Agency's 
interpretation of the CWA is that the antibacksliding requirements of 
section 402(o) of the CWA do not apply to revisions to effluent 
limitations made before the scheduled date of compliance for those 
limitations.
    State Compliance Schedule Provisions: EPA supports the State in 
adopting a statewide provision independent of or as part of the effort 
to readopt statewide water quality control plans, or in adopting 
individual basin-wide compliance schedule provisions through its nine 
Regional Water Quality Control Boards (RWQCBs). The State and RWQCBs 
have broad discretion to adopt a provision, including discretion on 
reasonable lengths of time for final compliance with WQBELs. EPA 
recognizes that practical time frames within which to set interim goals 
may be necessary to achieve meaningful, long-term improvements in water 
quality in California.
    At this time, two RWQCBs have adopted an authorizing compliance 
schedule provision as an amendment to

[[Page 31705]]

their respective Basin Plans during the Boards' last triennial review 
process. The Basin Plans have been adopted by the State and have come 
to EPA for approval. Thus, the Basin Plans' provisions are effective 
for the respective Basins. If and when EPA approves of either Regional 
Basin Plan, EPA will expeditiously act to amend the CTR, staying its 
compliance schedule provision, for the appropriate geographic region.

6. Changes From Proposed Rule

    A few changes were made in the final rule from the proposal both as 
a result of the Agency's consideration of issues raised in public 
comments and Endangered Species Act consultation with the U.S. Fish and 
Wildlife Service (FWS) and U.S. National Marine Fisheries Service 
(NMFS). The important changes include: reserving the mercury aquatic 
life criteria; reserving the selenium freshwater acute aquatic life 
criterion; reserving the chloroform human health criteria; and adding a 
sunset provision to the authorizing compliance schedule provision. EPA 
also clarified that the CTR will not replace priority toxic pollutant 
criteria which were adopted by the San Francisco Regional Water Quality 
Control Board in its 1986 Basin Plan, adopted by the State Board, and 
approved by EPA; specifying the harmonic mean for human health criteria 
for non-carcinogens and adding a provision which explicitly allows the 
State to adopt and implement an alternative averaging period, 
frequency, and design flow for a criterion after opportunity for public 
comment.
    The first two changes, the reservation of mercury criteria and 
selenium criterion, are discussed in more detail below in Section L., 
The Endangered Species Act (ESA). The selenium criterion is also 
discussed in more detail above in Section E., Derivation of Criteria, 
in subsection 2.b., Freshwater Acute Selenium Criterion. EPA has also 
decided to reserve a decision on numeric criteria for chloroform and 
therefore not promulgate chloroform criteria in the final rule. As part 
of a large-scale regulation promulgated in December l998 under the Safe 
Drinking Water Act, EPA published a health-based goal for chloroform 
(the maximum contaminant level goal or MCLG) of zero, see 63 FR 69390, 
Dec. 16, 1998. EPA provided new data and analyses concerning chloroform 
for public review and comment, including a different, mode of action 
approach for estimating the cancer risk, 63 FR 15674, March 31, 1998, 
but did not reach a conclusion on how to use that new information in 
establishing the final MCLG, pending further review by the Science 
Advisory Board. EPA has now concluded that any further actions on water 
quality criteria should take into account the new data and analysis as 
reviewed by the SAB. This decision is consistent with a recent federal 
court decision vacating the MCLG for chloroform (Chlorine Chemistry 
Council v. EPA, No. 98-1627 (DC Cir., Mar. 31,2000)). EPA intends to 
reassess the human health 304(a) criteria recommendation for 
chloroform. For these reasons, EPA has decided to reserve a decision on 
numeric criteria for chloroform in the CTR and not promulgate water 
quality criteria as proposed. Permitting authorities in California 
should continue to rely on existing narrative criteria to establish 
effluent limitations as necessary for chloroform.
    The sunset provision for the authorizing compliance schedule 
provision has been added to ease the transition from a Federal 
provision to the State's provision that was adopted in March 2000 as 
part of its' new statewide implementation plan. The sunset provision is 
discussed in more detail in Section G.5 of today's preamble. The CTR 
matrix at 40 CFR 131.38(b)(1) makes it explicit that the rule does not 
supplant priority toxic pollutant criteria which were adopted by the 
San Francisco Regional Water Quality Control Board in its 1986 Basin 
Plan, adopted by the State Board, and approved by EPA. This change is 
discussed more fully in Section D.4. of today's preamble. EPA modified 
the design flow for implementing human health criteria for non-
carcinogens from a 30Q5 to a harmonic mean. Human health criteria for 
non-carcinogens are based on an RfD, which is an acceptable daily 
exposure over a lifetime. EPA matched the criteria for protection over 
a human lifetime with the longest stream flow averaging period, i.e., 
the harmonic mean. Lastly, the CTR now contains language which is 
intended to make it easier for the State to adopt and implement an 
alternative averaging period, frequency and related design flow, for 
situations where the default parameters are inappropriate. This 
language is found at 40 CFR 131.38(c)(2)(iv).

H. Economic Analysis

    This final rule establishes ambient water quality criteria which, 
by themselves, do not directly impose economic impacts (see section K). 
These criteria combined with the State-adopted designated uses for 
inland surface waters, enclosed bays and estuaries, and implementation 
policies, will establish water quality standards. Until the State 
implements these water quality standards, there will be no effect of 
this rule on any entity. The State will implement these criteria by 
ensuring that NPDES permits result in discharges that will meet these 
criteria. In so doing, the State will have considerable discretion.
    EPA has analyzed the indirect potential costs and benefits of this 
rule. In order to estimate the indirect costs and benefits of the rule, 
an appropriate baseline must be established. The baseline is the 
starting point for measuring incremental costs and benefits of a 
regulation. The baseline is established by assessing what would occur 
in the absence of the regulation. At present, State Basin Plans contain 
a narrative water quality criterion stating that all waters shall be 
maintained free of toxic substances in concentrations that produce 
detrimental physiological responses in human, plant, animal, or aquatic 
life. EPA's regulation at 40 CFR 122.44(d)(1)(vi) requires that where a 
discharge causes or has the reasonable potential to cause an excursion 
above a narrative criterion within a State water quality standard, the 
permitting authority must establish effluent limits but may determine 
limits using a number of options. These options include establishing 
``effluent limits on a case-by-case basis, using EPA's water quality 
criteria published under section 304(a) of the CWA, supplemented where 
necessary by other relevant information'' (40 CFR 122.44(d)(1)(vi)(B)). 
Thus, to the extent that the State is implementing its narrative 
criteria by applying the CWA section 304(a) criteria, this rule does 
not impose any incremental costs because the criteria in this rule are 
identical to the CWA section 304(a) criteria. Alternatively, to the 
extent that the State is implementing its narrative criteria on a 
``case-by-case basis'' using ``other relevant information'' in its 
permits this rule may impose incremental indirect costs because the 
criteria in these permits may not be based on CWA 304(a) criteria. Both 
of these approaches to establishing effluent limits are in full 
compliance with the CWA.
    Because a specific basis for effluent limits in all existing 
permits in California is not known, it is not possible to determine a 
precise estimate of the indirect costs of this rule. The incremental 
costs of the rule may be as low as zero, or as high as $61 million. The 
high estimate of costs is based on the possibility that most of the 
effluent limits now in effect are not based on 304(a) criteria. EPA 
evaluated these

[[Page 31706]]

indirect costs using two different approaches. The first approach uses 
existing discharge data and makes assumptions about future State NPDES 
permit limits. Actual discharge levels are usually lower than the level 
set by current NPDES permit limits. This approach, representing the 
low-end scenario, also assumes that some of the discretionary 
mechanisms that would enhance flexibility (e.g., site specific 
criteria, mixing zones) would be granted by the State. The second 
approach uses a sample of existing permit limits and assumes that 
dischargers are actually discharging at the levels contained in their 
permits and makes assumptions about limits statewide that would be 
required under the rule. This approach, representing the high-end 
scenario, also assumes that none of the discretionary mechanisms that 
would enhance flexibility (e.g., site specific criteria, mixing zones) 
would be granted by the State. These two approaches recognize that the 
State has significant flexibility and discretion in how it chooses to 
implement standards within the NPDES permit program, the EA by 
necessity includes many assumptions about how the State will implement 
the water quality standards. These assumptions are based on a 
combination of EPA guidance and current permit conditions for the 
facilities examined in this analysis. To account for the uncertainty of 
EPA's implementation assumptions, this analysis estimates a wide range 
of costs and benefits. By completing the EA, EPA intends to inform the 
public about how entities might be potentially affected by State 
implementation of water quality standards in the NPDES permit program. 
The costs and benefits sections that follow summarize the methodology 
and results of the analysis.

1. Costs

    EPA assessed the potential compliance costs that facilities may 
incur to meet permit limits based on the criteria in today's rule. The 
analysis focused on direct compliance costs such as capital costs and 
operation and maintenance costs (O&M) for end-of-pipe pollution 
control, indirect source controls, pollution prevention, monitoring, 
and costs of pursuing alternative methods of compliance.
    The population of facilities with NPDES permits that discharge into 
California's enclosed bays, estuaries and inland surface waters 
includes 184 major dischargers and 1,057 minor dischargers. Of the 184 
major facilities, 128 are publicly owned treatment works (POTWs) and 56 
are industrial facilities. Approximately 2,144 indirect dischargers 
designated as significant industrial users discharge wastewater to 
those POTWs. In the EA for the proposed CTR, EPA used a three-phased 
process to select a sample of facilities to represent California 
dischargers potentially affected by the State's implementation of 
permit limits based on the criteria contained in this rule.
    The first phase consisted of choosing three case study areas for 
which data was thought to exist. The three case studies with a total of 
5 facilities included: the South San Francisco Bay (the San Jose/Santa 
Clara Water Pollution Control Plant and Sunnyvale Water Pollution 
Control Plant); the Sacramento River (the Sacramento Regional 
Wastewater Treatment Plant); and the Santa Ana River (the City of 
Riverside Water Quality Control Plant and the City of Colton Municipal 
Wastewater Treatment Facility). The second phase consisted of selecting 
five additional major industrial dischargers to complement the case-
study POTWs.
    The third phase involved selecting 10 additional facilities to 
improve the basis for extrapolating the costs of the selected sample 
facilities to the entire population of potentially affected 
dischargers. The additional 10 facilities were selected such that the 
group examined: (1) Was divided between major POTWs and major 
industrial discharger categories in proportion to the numbers of 
facilities in the State; (2) gave greater proportionate representation 
to major facilities than minor facilities based on a presumption that 
the majority of compliance costs would be incurred by major facilities; 
(3) gave a proportionate representation to each of four principal 
conventional treatment processes typically used by facilities in 
specified industries in California; and (4) was representative of the 
proportionate facilities located within the different California 
Regional Water Quality Control Boards. Within these constraints, 
facilities were selected at random to complete the sample.
    In the EA for today's final rule, EPA primarily used the same 
sample as the EA for the proposed rule with some modifications. EPA 
increased the number of minor POTWs and minor industrial facilities in 
the sample. EPA randomly selected four new minor POTW facilities and 
five new minor industrial facilities to add to the sample. The number 
of sample facilities selected in each area under the jurisdiction of a 
Regional Water Quality Control Board was roughly proportional to the 
universe of facilities in each area.
    For those facilities that were projected to exceed permit limits 
based on the criteria, EPA estimated the incremental costs of 
compliance. Using a decision matrix or flow chart, costs were developed 
for two different scenarios--a ``low-end'' cost scenario and a ``high-
end'' cost scenario--to account for a range of regulatory flexibility 
available to the State when implementing permit limits based on the 
water quality criteria. The assumptions for baseline loadings also vary 
over the two scenarios. The low-end scenario generally assumed that 
facilities were discharging at the maximum effluent concentrations 
taken from actual monitoring data, while the high-end scenario 
generally assumed that facilities were discharging at their current 
effluent limits. The decision matrix specified assumptions used for 
selection of control options, such as optimization of existing 
treatment processes and operations, in-plant pollutant minimization and 
prevention, and end-of-pipe treatment.
    The annualized potential costs that direct and indirect dischargers 
may incur as a result of State implementation of permit limits based on 
water quality standards using today's criteria are estimated to be 
between $33.5 million and $61 million. EPA believes that the costs 
incurred as a result of State implementation of these permit limits 
will approach the low-end of the cost range. Costs are unlikely to 
reach the high-end of the range because State authorities are likely to 
choose implementation options that provide some degree of flexibility 
or relief to point source dischargers. Furthermore, cost estimates for 
both scenarios, but especially for the high-end scenario, may be 
overstated because the analysis tended to use conservative assumptions 
in calculating these permit limits and in establishing baseline 
loadings. The baseline loadings for the high-end were based on current 
effluent limits rather than actual pollutant discharge data. Most 
facilities discharge pollutants in concentrations well below current 
effluent limits. In addition, both the high-end and low-end cost 
estimates in the EA may be slightly overstated since potential costs 
incurred to reduce chloroform discharges were included in these 
estimates. EPA made a decision to reserve the chloroform human health 
criteria after the EA was completed.
    Under the low-end cost scenario, major industrial facilities and 
POTWs would incur about 27 percent of the potential costs, indirect 
dischargers would incur about 70 percent of the potential costs, while 
minor dischargers would incur about 3 percent. Of the major direct 
dischargers, POTWs would incur the largest share of projected costs (87 
percent). However, distributed

[[Page 31707]]

among 128 major POTWs in the State, the average cost per plant would be 
$61,000 per year. Chemical and petroleum industries would incur the 
highest cost of the industrial categories (5.6 percent of the annual 
costs, with an annual average of $25,200 per plant). About 57 percent 
of the low-end costs would be associated with pollution prevention 
activities, while nearly 38 percent would be associated with pursuing 
alternative methods of compliance under the regulations.
    Under the high-end cost scenario, major industrial facilities and 
POTWs would incur about 94 percent of the potential costs, indirect 
dischargers would incur about 17 percent of the potential costs, while 
minor dischargers would incur about 5 percent. Among the major, direct 
dischargers, two categories would incur the majority of potential 
costs--major POTWs (82 percent), Chemical/Petroleum Products (9 
percent). The average annual per plant cost for different industry 
categories would ranges from zero to $324,000. The two highest average 
cost categories would be major POTWs ($324,000 per year) and Chemical/
Petroleum Products ($221,264 per year). The shift in proportion of 
potential costs between direct and indirect dischargers is due to the 
assumption that more direct dischargers would use end-of-pipe treatment 
under the high-end scenario. Thus, a smaller proportion of indirect 
dischargers would be impacted under the high-end scenario, since some 
municipalities are projected to add end-of-pipe treatment which would 
reduce the need for controls from indirect discharges. Over 91 percent 
of the annual costs are for waste minimization and treatment 
optimization costs. Waste minimization would represent nearly 84% of 
the total annual costs. Capital and operation and maintenance costs 
would make up less than 9 percent of annual costs.
    Cost-Effectiveness: Cost-effectiveness is estimated in terms of the 
cost of reducing the loadings of toxic pollutants from point sources. 
The cost-effectiveness is derived by dividing the projected annual 
costs of implementing permit limits based on water quality standards 
using today's criteria by the toxicity-weighted pounds (pound-
equivalents) of pollutants removed. Pound-equivalents are calculated by 
multiplying pounds of each pollutant removed by the toxic weight (based 
on the toxicity of copper) for that pollutant.
    Based on this analysis, State implementation of permit limits based 
on today's criteria would be responsible for the reduction of about 1.1 
million to 2.7 million toxic pound-equivalents per year, or 15 to 50 
percent of the toxic-weighted baseline loadings for the high-and low-
end scenarios, respectively. The cost-effectiveness of the scenarios 
would range from $22 (high-end scenario) to $31 (low-end scenario) per 
pound-equivalent.

2. Benefits

    The benefits analysis is intended to provide insight into both the 
types and potential magnitude of the economic benefits expected as a 
result of implementation of water quality standards based on today's 
criteria. To the extent feasible, empirical estimates of the potential 
magnitude of the benefits were developed and then compared to the 
estimated costs of implementing water quality standards based on 
today's criteria.
    To perform a benefits analysis, the types or categories of benefits 
that apply need to be defined. EPA relied on a set of benefits 
categories that typically apply to changes in the water resource 
environment. Benefits were categorized as either use benefits or 
passive (nonuse) benefits depending on whether or not they involve 
direct use of, or contact with, the resource. The most prominent use 
benefit categories are those related to recreational fishing, boating, 
and swimming. Another use benefit category of significance is human 
health risk reduction. Human health risk reductions can be realized 
through actions that reduce human exposure to contaminants such as 
exposure through the consumption of fish containing elevated levels of 
pollutants. Passive use benefits are those improvements in 
environmental quality that are valued by individuals apart from any use 
of the resource in question.
    Benefits estimates were derived in this study using an approach in 
which benefits of discrete large-scale changes in water quality beyond 
present day conditions were estimated wherever feasible. A share of 
those benefits was then apportioned to implementation of water quality 
standards based on today's criteria. The apportionment estimate was 
based on a three-stage process:
    First, EPA assessed current total loadings from all sources that 
are contributing to the toxics-related water quality problems observed 
in the State. This defines the overall magnitude of loadings. Second, 
the share of total loadings that are attributable to sources that would 
be controlled through implementation of water quality standards based 
on today's criteria was estimated. Since this analysis was designed to 
focus only on those controls imposed on point sources, this stage of 
the process entailed estimating the portion of total loadings 
originating from point sources. Third, the percentage reduction in 
loadings expected due to implementation of today's criteria was 
estimated and then multiplied by the share of point source loadings to 
calculate the portion of benefits that could be attributed to 
implementation of water quality standards based on today's criteria.
    Total monetized annual benefits were estimated in the range of $6.9 
to $74.7 million. By category, annual benefits would be $1.3 to $4.6 
million for avoided cancer risk, $2.2 to $15.2 million for recreational 
angling, and $3.4 to $54.9 million for passive use benefits.
    There are numerous categories of potential or likely benefits that 
have been omitted from the quantified and monetized benefit estimates. 
In terms of potential magnitudes of benefit, the following are likely 
to be significant contributors to the underestimation of the monetized 
values presented above:
     Improvements in water-related (in-stream and near stream) 
recreation apart from fishing. The omission of potential motorized and 
nonmotorized boating, swimming, picnicking, and related in-stream and 
stream-side recreational activities from the benefits estimates could 
contribute to an appreciable underestimation of total benefits. Such 
recreational activities have been shown in empirical research to be 
highly valued, and even modest changes in participation and or user 
values could lead to sizable benefits statewide. Some of these 
activities can be closely associated with water quality attributes 
(notably, swimming). Other recreational activities may be less directly 
related to the water quality improvements, but might nonetheless 
increase due to their association with fishing, swimming, or other 
activities in which the participants might engage.
     Improvements in consumptive and nonconsumptive land-based 
recreation, such as hunting and wildlife observation. Improvements in 
aquatic habitats may lead (via food chain and related ecologic benefit 
mechanisms) to healthier, larger, and more diverse populations of avian 
and terrestrial species, such as waterfowl, eagles, and otters. 
Improvements in the populations for these species could manifest as 
improved hunting and wildlife viewing opportunities, which might in 
turn increase participation and user day values for such activities. 
Although the scope of the benefits analysis has not allowed a 
quantitative assessment of these values at either pre- or post-rule

[[Page 31708]]

conditions, it is conceivable that these benefits could be appreciable.
     Improvements in human health resulting from reduction of 
non-cancer risk. EPA estimated that implementation of water quality 
standards based on the criteria would result in a reduction of mercury 
concentrations in fish tissue and, thus, a reduction in the hazard from 
consumption of mercury contaminated fish. However, EPA was unable to 
monetize benefits due to reduced non-cancer health effects.
     Human health benefits for saltwater anglers outside of San 
Francisco Bay were not estimated. The number of saltwater anglers 
outside of San Francisco Bay is estimated to be 673,000 (based on 
Huppert, 1989, and U.S. FWS, 1993). The omission of other saltwater 
anglers may cause human health benefits to be underestimated. In 
addition, benefit estimates in the EA may be slightly overstated since 
potential benefits from reductions in chloroform discharges were 
included in these estimates. EPA made a decision to reserve the 
chloroform human health criteria after the EA was completed.
    EPA received a number of comments which requested the Agency use 
the cost-benefit analysis in the EA as a factor in setting water 
quality criteria. EPA does not use the EA as a basis in determining 
protective water quality criteria. EPA's current regulations at 40 CFR 
131.11 state that the criteria must be based on sound scientific 
rationale and must protect the designated use. From the outset of the 
water quality standards program, EPA has explained that while economic 
factors may be considered in designating uses, they may not be used to 
justify criteria that are not protective of those uses. 44 FR 25223-
226, April 30, 1979. See e.g. Mississippi Commission on Natural 
Resources v. Costle, 625 F. 2d 1269, 1277 (5th Cir. 1980). EPA 
reiterated this interpretation of the CWA and its implementing 
regulations in discussing section 304(a) recommended criteria guidance 
stating that ``they are based solely on data and scientific judgments 
on the relationship between pollutant concentrations and environmental 
and human health effects and do not reflect consideration of economic 
impacts or the technological feasibility of meeting the chemical 
concentrations in ambient water.'' 63 FR 36742 and 36762, July 7, 1998.

I. 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 Office of Management and Budget (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.
    It has been determined that this rule is not a ``significant 
regulatory action'' under the terms of Executive Order 12866 and is 
therefore not subject to OMB review.

J. Unfunded Mandates Reform Act of 1995

    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 any regulation 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 an Agency 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 the affected small governments 
to have meaningful and timely input in the development of regulatory 
proposals with significant Federal intergovernmental mandates, and EPA 
informing, educating, and advising small governments on compliance with 
the regulatory requirements.
    Today's rule contains no Federal mandates (under the regulatory 
provisions of Title II of the Unfunded Mandates Reform Act (UMRA)) for 
State, local, or tribal governments or the private sector. Today's rule 
imposes no enforceable duty on any State, local or Tribal governments 
or the private sector; rather, the CTR promulgates ambient water 
quality criteria which, when combined with State-adopted uses, will 
create water quality standards for those water bodies with adopted 
uses. The State will then use these resulting water quality standards 
in implementing its existing water quality control programs. Thus, 
today's rule is not subject to the requirements of sections 202 and 205 
of the UMRA.
    EPA has determined that this rule contains no regulatory 
requirements that might significantly or uniquely affect small 
governments. This rule establishes ambient water quality criteria 
which, by themselves do not directly impact any entity. The State will 
implement these criteria by ensuring that NPDES permits result in 
discharges that will meet these criteria. In so doing, the State will 
have considerable discretion. Until the State implements these water 
quality standards, there will be no effect of this rule on any entity. 
Thus, today's rule is not subject to the requirements of section 203 of 
UMRA.

K. Regulatory Flexibility Act

    The Regulatory Flexibility Act generally requires Federal agencies 
to prepare a regulatory flexibility analysis of any rule subject to 
notice and comment rulemaking requirements under the Administrative 
Procedure Act or any other statute unless the Agency certifies that the 
rule will not have a significant economic impact of a substantial 
number of small entities. Small entities include small businesses, 
small organizations, and small governmental jurisdictions. For purposes 
of assessing the impacts of today's rule on small entities, small 
entity is defined as: (1) A small business according to RFA default 
definitions for small businesses (based on SBA size

[[Page 31709]]

standards); (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.
    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. This final 
rule will not impose any requirements on small entities.
    Under the CWA water quality standards program, States must adopt 
water quality standards for their waters that must be submitted to EPA 
for approval. If the Agency disapproves a State standard and the State 
does not adopt appropriate revisions to address EPA's disapproval, EPA 
must promulgate standards consistent with the statutory requirements. 
EPA has authority to promulgate criteria or standards in any case where 
the Administrator determines that a revised or new standard is 
necessary to meet the requirements of the Act. These State standards 
(or EPA-promulgated standards) are implemented through various water 
quality control programs including the National Pollutant Discharge 
Elimination System (NPDES) program that limits discharges to navigable 
waters except in compliance with an EPA permit or permit issued under 
an approved State NPDES program. The CWA requires that all NPDES 
permits must include any limits on discharges that are necessary to 
meet State water quality standards.
    Thus, under the CWA, EPA's promulgation of water quality criteria 
or standards establishes standards that the State, in turn, implements 
through the NPDES permit process. The State has considerable discretion 
in deciding how to meet the water quality standards and in developing 
discharge limits as needed to meet the standards. In circumstances 
where there is more than one discharger to a water body that is subject 
to water quality standards or criteria, a State also has discretion in 
deciding on the appropriate limits for the different dischargers. While 
the State's implementation of federally-promulgated water quality 
criteria or standards may result indirectly in new or revised discharge 
limits for small entities, the criteria or standards themselves do not 
apply to any discharger, including small entities.
    Today's rule, as explained above, does not itself establish any 
requirements that are applicable to small entities. As a result of 
EPA's action here, the State of California will need to ensure that 
permits it issues include limits as necessary to meet the water quality 
standards established by the criteria in today's rule. In so doing, the 
State will have a number of discretionary choices associated with 
permit writing. While California's implementation of today's rule may 
ultimately result in some new or revised permit conditions for some 
dischargers, including small entities, EPA's action today does not 
impose any of these as yet unknown requirements on small entities.
    The RFA requires analysis of the economic impact of a rule only on 
the small entities subject to the rule's requirements. Courts have 
consistently held that the RFA imposes no obligation on an Agency to 
prepare a small entity analysis of the effect of a rule on entities not 
regulated by the rule. Motor & Equip. Mrfrs. Ass'n v. Nichols, 142 F.3d 
449, 467 & n.18 (D.C. Cir. 1998)(quoting United States Distribution 
Companies v. FERC, 88 F.3d 1105, 1170 (D.C. Cir. 1996); see also 
American Trucking Association, Inc. v. EPA, 175 F.3d 1027 (D.C. Cir. 
1999). This final rule will have a direct effect only on the State of 
California which is not a small entity under the RFA. Thus, individual 
dischargers, including small entities, are not directly subject to the 
requirements of the rule. Moreover, because of California's discretion 
in implementing these standards, EPA cannot assess the extent to which 
the promulgation of this rule may subsequently affect any dischargers, 
including small entities. Consequently, certification under section 
605(b) is appropriate. State of Michigan, et al. v. U.S. Environmental 
Protection Agency, No. 98-1497 (D.C. Cir. Mar. 3, 2000), slip op. at 
41-42.

L. Paperwork Reduction Act

    This action requires no new or additional information collection, 
reporting, or record keeping subject to the Paperwork Reduction Act, 44 
U.S.C. 3501 et seq.

M. Endangered Species Act

    Pursuant to section 7(a) of the Endangered Species Act (ESA), EPA 
has consulted with the U.S. Fish and Wildlife Service and the U.S. 
National Marine Fisheries Service (collectively, the Services) 
concerning EPA's rulemaking action for the State of California. EPA 
initiated informal consultation in early 1994, and completed formal 
consultation in April 2000. As a result of the consultation, EPA 
modified some of the provisions in the final rule.
    As part of the consultation process, EPA submitted to the Services 
a Biological Evaluation for their review in October of 1997. This 
evaluation found that the proposed CTR was not likely to jeopardize the 
continued existence of any Federally listed species or result in the 
destruction or adverse modification of designated critical habitat. In 
April of 1998, the Services sent EPA a draft Biological Opinion which 
tentatively found that EPA's proposed rule would jeopardize the 
continued existence of several Federally listed species and result in 
the destruction or have adverse effect on designated critical habitat. 
After lengthy discussions with the Services, EPA agreed to several 
changes in the final rule and the Services in turn issued a final 
Biological Opinion finding that EPA's action would not likely 
jeopardize the continued existence of any Federally listed species or 
result in the destruction or adverse modification of designated 
critical habitat. EPA's Biological Evaluation and the Services' final 
Biological Opinion are contained in the administrative record for 
today's rule.
    In order to ensure the continued protection of Federally listed 
threatened and endangered species and to protect their critical 
habitat, EPA agreed to reserve the aquatic life criteria for mercury 
and the acute freshwater aquatic life criterion for selenium. The 
Services believe that EPA's proposed criteria are not sufficiently 
protective of Federally listed species and should not be promulgated. 
EPA agreed that it would reevaluate these criteria in light of the 
Services concerns before promulgating them for the State of California. 
Other commitments made by EPA are described in a letter to the Services 
dated December 16, 1999; this letter is contained in the administrative 
record for today's rule.

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 rule is not a major rule as defined

[[Page 31710]]

by 5 U.S.C. 804(2). This rule will be effective May 18, 2000.

O. Executive Order 13084, Consultation and Coordination With Indian 
Tribal Governments

    Under Executive Order 13084, EPA may not issue a regulation that is 
not required by statute, that significantly or uniquely affects the 
communities of Indian tribal governments, and that imposes substantial 
direct compliance costs on those communities, unless the Federal 
government provides the funds necessary to pay the direct compliance 
costs incurred by the tribal governments, or EPA consults with those 
governments. If EPA complies by consulting, Executive Order 13084 
requires EPA to provide to the Office of Management and Budget, in a 
separately identified section of the preamble to the rule, a 
description of the extent of EPA's prior consultation with 
representatives of affected tribal governments, a summary of the nature 
of their concerns, and a statement supporting the need to issue the 
regulation. In addition, Executive Order 13084 requires EPA to develop 
an effective process permitting elected officials and other 
representatives of Indian tribal governments ``to provide meaningful 
and timely input in the development of regulatory policies on matters 
that significantly or uniquely affect their communities.''
    Today's rule does not significantly or uniquely affect the 
communities of Indian tribal governments nor does it impose substantial 
direct compliance cots on them. Today's rule will only address priority 
toxic pollutant water quality criteria for the State of California and 
does not apply to waters in Indian country. Accordingly, the 
requirements of section 3(b) of Executive Order 13084 do not apply to 
this rule.

P. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (``NTTAA''), Public Law No. 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 standards 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 final rule does not involve technical standards. Therefore, 
EPA did not consider the use of any voluntary consensus standards.

Q. Executive Order 13132 on 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.''
    Under section 6 of Executive Order 13132, EPA may not issue a 
regulation that has federalism 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 State and local governments, or EPA 
consults with State and local officials early in the process of 
developing the proposed regulation. EPA also may not issue a regulation 
that has federalism implications and that preempts State law, unless 
the Agency consults with State and local officials early in the process 
of developing the proposed regulation.
    This final rule does not have federalism implications. It will not 
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, 
as specified in Executive Order 13132. The rule does not affect the 
nature of the relationship between EPA and States generally, for the 
rule only applies to water bodies in California. Further, the rule will 
not substantially affect the relationship of EPA and the State of 
California, or the distribution of power or responsibilities between 
EPA and the State. The rule does not alter the State's authority to 
issue NPDES permits or the State's considerable discretion in 
implementing these criteria. The rule simply implements Clean Water Act 
section 303(c)(2)(B) requiring numeric ambient water quality criteria 
for which EPA has issued section 304(a) recommended criteria in a 
manner that is consistent with previous regulatory guidance that the 
Agency has issued to implement CWA section 303(c)(2)(B). Further, this 
rule does not preclude the State from adopting water quality standards 
that meet the requirements of the CWA. Thus, the requirements of 
section 6 of the Executive Order do not apply to this rule.
    Although section 6 of Executive Order 13132 does not apply to this 
rule, EPA did consult with State and local government representatives 
in developing this rule. EPA and the State reached an agreement that to 
best utilize its respective resources, EPA would promulgate water 
quality criteria and the State would concurrently work on a plan to 
implement the criteria. Since the proposal of this rule, EPA has kept 
State officials fully informed of changes to the proposal. EPA has 
continued to invite comment from the State on these changes. EPA 
believes that the final CTR incorporates comments from State officials 
and staff.

R. Executive Order 13045 on 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 Executive Order 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, 
we nonetheless have reason to believe that the environmental health or 
safety risk addressed by this action may have a disproportionate effect 
on children. As a matter of EPA policy, we therefore have assessed the 
environmental health or safety effects of ambient water quality 
criteria on children. The results of this assessment are contained in 
section F.3., Human Health Criteria.

List of Subjects in 40 CFR Part 131

    Environmental protection, Indians--lands, Intergovernmental 
relations, Reporting and recordkeeping requirements, Water pollution 
control.


[[Page 31711]]


    Dated: April 27, 2000.
Carol Browner,
Administrator.

    For the reasons set out in the preamble, part 131 of chapter I of 
title 40 of the Code of Federal Regulations is amended as follows:

PART 131--WATER QUALITY STANDARDS

    1. The authority citation for part 131 continues to read as 
follows:

    Authority: 33 U.S.C. 1251 et seq.

Subpart D--[Amended]

    2. Section 131.38 is added to subpart D to read as follows:


Sec. 131.38  Establishment of Numeric Criteria for Priority Toxic 
Pollutants for the State of California.

    (a) Scope. This section promulgates criteria for priority toxic 
pollutants in the State of California for inland surface waters and 
enclosed bays and estuaries. This section also contains a compliance 
schedule provision.
    (b)(1) Criteria for Priority Toxic Pollutants in the State of 
California as described in the following table:

BILLING CODE 6560-50-P

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[GRAPHIC] [TIFF OMITTED] TR18MY00.007


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[GRAPHIC] [TIFF OMITTED] TR18MY00.008


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[GRAPHIC] [TIFF OMITTED] TR18MY00.009


[[Page 31715]]


[GRAPHIC] [TIFF OMITTED] TR18MY00.010

BILLING CODE 6560-50-C

[[Page 31716]]

Footnotes to Table in Parargraph (b)(1):

    a. Criteria revised to reflect the Agency q1* or RfD, as 
contained in the Integrated Risk Information System (IRIS) as of 
October 1, 1996. The fish tissue bioconcentration factor (BCF) from 
the 1980 documents was retained in each case.
    b. Criteria apply to California waters except for those waters 
subject to objectives in Tables III-2A and III-2B of the San 
Francisco Regional Water Quality Control Board's (SFRWQCB) 1986 
Basin Plan, that were adopted by the SFRWQCB and the State Water 
Resources Control Board, approved by EPA, and which continue to 
apply.
    c. Criteria are based on carcinogenicity of 10 (-6) risk.
    d. Criteria Maximum Concentration (CMC) equals the highest 
concentration of a pollutant to which aquatic life can be exposed 
for a short period of time without deleterious effects. Criteria 
Continuous Concentration (CCC) equals the highest concentration of a 
pollutant to which aquatic life can be exposed for an extended 
period of time (4 days) without deleterious effects. ug/L equals 
micrograms per liter.
    e. Freshwater aquatic life criteria for metals are expressed as 
a function of total hardness (mg/L) in the water body. The equations 
are provided in matrix at paragraph (b)(2) of this section. Values 
displayed above in the matrix correspond to a total hardness of 100 
mg/l.
    f. Freshwater aquatic life criteria for pentachlorophenol are 
expressed as a function of pH, and are calculated as follows: Values 
displayed above in the matrix correspond to a pH of 7.8. CMC = 
exp(1.005(pH)-4.869). CCC = exp(1.005(pH)-5.134).
    g. This criterion is based on 304(a) aquatic life criterion 
issued in 1980, and was issued in one of the following documents: 
Aldrin/Dieldrin (EPA 440/5-80-019), Chlordane (EPA 440/5-80-027), 
DDT (EPA 440/5-80-038), Endosulfan (EPA 440/5-80-046), Endrin (EPA 
440/5-80-047), Heptachlor (440/5-80-052), Hexachlorocyclohexane (EPA 
440/5-80-054), Silver (EPA 440/5-80-071). The Minimum Data 
Requirements and derivation procedures were different in the 1980 
Guidelines than in the 1985 Guidelines. For example, a ``CMC'' 
derived using the 1980 Guidelines was derived to be used as an 
instantaneous maximum. If assessment is to be done using an 
averaging period, the values given should be divided by 2 to obtain 
a value that is more comparable to a CMC derived using the 1985 
Guidelines.
    h. These totals simply sum the criteria in each column. For 
aquatic life, there are 23 priority toxic pollutants with some type 
of freshwater or saltwater, acute or chronic criteria. For human 
health, there are 92 priority toxic pollutants with either ``water + 
organism'' or ``organism only'' criteria. Note that these totals 
count chromium as one pollutant even though EPA has developed 
criteria based on two valence states. In the matrix, EPA has 
assigned numbers 5a and 5b to the criteria for chromium to reflect 
the fact that the list of 126 priority pollutants includes only a 
single listing for chromium.
    i. Criteria for these metals are expressed as a function of the 
water-effect ratio, WER, as defined in paragraph (c) of this 
section. CMC = column B1 or C1 value x WER; CCC = column B2 or C2 
value x WER.
    j. No criterion for protection of human health from consumption 
of aquatic organisms (excluding water) was presented in the 1980 
criteria document or in the 1986 Quality Criteria for Water. 
Nevertheless, sufficient information was presented in the 1980 
document to allow a calculation of a criterion, even though the 
results of such a calculation were not shown in the document.
    k. The CWA 304(a) criterion for asbestos is the MCL.
    l. [Reserved]
    m. These freshwater and saltwater criteria for metals are 
expressed in terms of the dissolved fraction of the metal in the 
water column. Criterion values were calculated by using EPA's Clean 
Water Act 304(a) guidance values (described in the total recoverable 
fraction) and then applying the conversion factors in 
Sec. 131.36(b)(1) and (2).
    n. EPA is not promulgating human health criteria for these 
contaminants. However, permit authorities should address these 
contaminants in NPDES permit actions using the State's existing 
narrative criteria for toxics.
    o. These criteria were promulgated for specific waters in 
California in the National Toxics Rule (``NTR''), at Sec. 131.36. 
The specific waters to which the NTR criteria apply include: Waters 
of the State defined as bays or estuaries and waters of the State 
defined as inland, i.e., all surface waters of the State not ocean 
waters. These waters specifically include the San Francisco Bay 
upstream to and including Suisun Bay and the Sacramento-San Joaquin 
Delta. This section does not apply instead of the NTR for this 
criterion.
    p. A criterion of 20 ug/l was promulgated for specific waters in 
California in the NTR and was promulgated in the total recoverable 
form. The specific waters to which the NTR criterion applies 
include: Waters of the San Francisco Bay upstream to and including 
Suisun Bay and the Sacramento-San Joaquin Delta; and waters of Salt 
Slough, Mud Slough (north) and the San Joaquin River, Sack Dam to 
the mouth of the Merced River. This section does not apply instead 
of the NTR for this criterion. The State of California adopted and 
EPA approved a site specific criterion for the San Joaquin River, 
mouth of Merced to Vernalis; therefore, this section does not apply 
to these waters.
    q. This criterion is expressed in the total recoverable form. 
This criterion was promulgated for specific waters in California in 
the NTR and was promulgated in the total recoverable form. The 
specific waters to which the NTR criterion applies include: Waters 
of the San Francisco Bay upstream to and including Suisun Bay and 
the Sacramento-San Joaquin Delta; and waters of Salt Slough, Mud 
Slough (north) and the San Joaquin River, Sack Dam to Vernalis. This 
criterion does not apply instead of the NTR for these waters. This 
criterion applies to additional waters of the United States in the 
State of California pursuant to 40 CFR 131.38(c). The State of 
California adopted and EPA approved a site-specific criterion for 
the Grassland Water District, San Luis National Wildlife Refuge, and 
the Los Banos State Wildlife Refuge; therefore, this criterion does 
not apply to these waters.
    r. These criteria were promulgated for specific waters in 
California in the NTR. The specific waters to which the NTR criteria 
apply include: Waters of the State defined as bays or estuaries 
including the San Francisco Bay upstream to and including Suisun Bay 
and the Sacramento-San Joaquin Delta. This section does not apply 
instead of the NTR for these criteria.
    s. These criteria were promulgated for specific waters in 
California in the NTR. The specific waters to which the NTR criteria 
apply include: Waters of the Sacramento-San Joaquin Delta and waters 
of the State defined as inland ( i.e., all surface waters of the 
State not bays or estuaries or ocean) that include a MUN use 
designation. This section does not apply instead of the NTR for 
these criteria.
    t. These criteria were promulgated for specific waters in 
California in the NTR. The specific waters to which the NTR criteria 
apply include: Waters of the State defined as bays and estuaries 
including San Francisco Bay upstream to and including Suisun Bay and 
the Sacramento-San Joaquin Delta; and waters of the State defined as 
inland (i.e., all surface waters of the State not bays or estuaries 
or ocean) without a MUN use designation. This section does not apply 
instead of the NTR for these criteria.
    u. PCBs are a class of chemicals which include aroclors 1242, 
1254, 1221, 1232, 1248, 1260, and 1016, CAS numbers 53469219, 
11097691, 11104282, 11141165, 12672296, 11096825, and 12674112, 
respectively. The aquatic life criteria apply to the sum of this set 
of seven aroclors.
    v. This criterion applies to total PCBs, e.g., the sum of all 
congener or isomer or homolog or aroclor analyses.
    w. This criterion has been recalculated pursuant to the 1995 
Updates: Water Quality Criteria Documents for the Protection of 
Aquatic Life in Ambient Water, Office of Water, EPA-820-B-96-001, 
September 1996. See also Great Lakes Water Quality Initiative 
Criteria Documents for the Protection of Aquatic Life in Ambient 
Water, Office of Water, EPA-80-B-95-004, March 1995.
    x. The State of California has adopted and EPA has approved site 
specific criteria for the Sacramento River (and tributaries) above 
Hamilton City; therefore, these criteria do not apply to these 
waters.

General Notes to Table in Paragraph (b)(1)

    1. The table in this paragraph (b)(1) lists all of EPA's 
priority toxic pollutants whether or not criteria guidance are 
available. Blank spaces indicate the absence of national section 
304(a) criteria guidance. Because of variations in chemical 
nomenclature systems, this listing of toxic pollutants does not 
duplicate the listing in Appendix A to 40 CFR Part 423-126 Priority 
Pollutants. EPA has added the Chemical Abstracts Service (CAS) 
registry numbers, which provide a unique identification for each 
chemical.
    2. The following chemicals have organoleptic-based criteria 
recommendations that are not included on this chart: zinc, 3-methyl-
4-chlorophenol.

[[Page 31717]]

    3. Freshwater and saltwater aquatic life criteria apply as 
specified in paragraph (c)(3) of this section.

    (2) Factors for Calculating Metals Criteria. Final CMC and CCC 
values should be rounded to two significant figures.

  (i) CMC = WER  x  (Acute Conversion Factor)  x  (exp{mA[1n 
(hardness)]+bA})
  (ii) CCC = WER  x  (Acute Conversion Factor)  x  
(exp{mC[1n (hardness)]+bC})
  (iii) Table 1 to paragraph (b)(2) of this section:

----------------------------------------------------------------------------------------------------------------
                      Metal                             mA              bA              mC              bC
----------------------------------------------------------------------------------------------------------------
Cadmium.........................................          1.128          -3.6867          0.7852         -2.715
Copper..........................................          0.9422         -1.700           0.8545         -1.702
Chromium (III)..................................          0.8190          3.688           0.8190          1.561
Lead............................................          1.273          -1.460           1.273          -4.705
Nickel..........................................          0.8460          2.255           0.8460          0.0584
Silver..........................................          1.72           -6.52
Zinc............................................          0.8473          0.884           0.8473          0.884
----------------------------------------------------------------------------------------------------------------
Note to Table 1: The term ``exp'' represents the base e exponential function.

    (iv) Table 2 to paragraph (b)(2) of this section:

----------------------------------------------------------------------------------------------------------------
                                                    Conversion        CF for                         CF a for
                                                 factor (CF) for    freshwater        CF for         saltwater
                     Metal                          freshwater        chronic        saltwater        chronic
                                                  acute criteria     criteria     acute criteria     criteria
----------------------------------------------------------------------------------------------------------------
Antimony.......................................         (d)              (d)             (d)             (d)
Arsenic........................................           1.000            1.000           1.000           1.000
Beryllium......................................         (d)              (d)             (d)             (d)
Cadmium........................................         b 0.944          b 0.909           0.994           0.994
Chromium (III).................................           0.316            0.860         (d)             (d)
Chromium (VI)..................................           0.982            0.962           0.993           0.993
Copper.........................................           0.960            0.960           0.83            0.83
Lead...........................................         b 0.791          b 0.791           0.951           0.951
Mercury........................................  ...............  ..............  ..............  ..............
Nickel.........................................           0.998            0.997           0.990           0.990
Selenium.......................................  ...............         (c)               0.998           0.998
Silver.........................................           0.85           (d)               0.85          (d)
Thallium.......................................         (d)              (d)             (d)             (d)
Zinc...........................................           0.978            0.986           0.946           0.946 
----------------------------------------------------------------------------------------------------------------
Footnotes to Table 2 of Paragraph (b)(2):
a Conversion Factors for chronic marine criteria are not currently available. Conversion Factors for acute
  marine criteria have been used for both acute and chronic marine criteria.
b Conversion Factors for these pollutants in freshwater are hardness dependent. CFs are based on a hardness of
  100 mg/l as calcium carbonate (CaCO3). Other hardness can be used; CFs should be recalculated using the
  equations in table 3 to paragraph (b)(2) of this section.
c Bioaccumulative compound and inappropriate to adjust to percent dissolved.
d EPA has not published an aquatic life criterion value.


    Note to Table 2 of Paragraph (b)(2): The term ``Conversion 
Factor'' represents the recommended conversion factor for converting 
a metal criterion expressed as the total recoverable fraction in the 
water column to a criterion expressed as the dissolved fraction in 
the water column. See ``Office of Water Policy and Technical 
Guidance on Interpretation and Implementation of Aquatic Life Metals 
Criteria'', October 1, 1993, by Martha G. Prothro, Acting Assistant 
Administrator for Water available from Water Resource Center, USEPA, 
Mailcode RC4100, M Street SW, Washington, DC, 20460 and the note to 
Sec. 131.36(b)(1).

    (v) Table 3 to paragraph (b)(2) of this section:

------------------------------------------------------------------------
                                      Acute                Chronic
------------------------------------------------------------------------
Cadmium.....................  CF=1.136672--[(ln     CF = 1.101672--[(ln
                               {hardness})           {hardness})(0.04183
                               (0.041838)].          8)]
Lead........................  CF=1.46203--[(ln      CF = 1.46203--[(ln
                               {hardness})(0.14571   {hardness})(0.14571
                               2)].                  2)]
------------------------------------------------------------------------

    (c) Applicability. (1) The criteria in paragraph (b) of this 
section apply to the State's designated uses cited in paragraph (d) of 
this section and apply concurrently with any criteria adopted by the 
State, except when State regulations contain criteria which are more 
stringent for a particular parameter and use, or except as provided in 
footnotes p, q, and x to the table in paragraph (b)(1) of this section.
    (2) The criteria established in this section are subject to the 
State's general rules of applicability in the same way and to the same 
extent as are other Federally-adopted and State-adopted numeric toxics 
criteria when applied to the same use classifications including mixing 
zones, and low flow values below which numeric standards can be 
exceeded in flowing fresh waters.
    (i) For all waters with mixing zone regulations or implementation 
procedures, the criteria apply at the appropriate locations within or 
at the boundary of the mixing zones; otherwise the criteria apply 
throughout the water body including at the point of discharge into the 
water body.
    (ii) The State shall not use a low flow value below which numeric 
standards can be exceeded that is less stringent than the flows in 
Table 4 to paragraph (c)(2) of this section for streams and rivers.
    (iii) Table 4 to paragraph (c)(2) of this section:

[[Page 31718]]



------------------------------------------------------------------------
                 Criteria                            Design flow
------------------------------------------------------------------------
Aquatic Life Acute Criteria (CMC).........  1 Q 10 or 1 B 3
Aquatic Life Chronic Criteria (CCC).......  7 Q 10 or 4 B 3
Human Health Criteria.....................  Harmonic Mean Flow
------------------------------------------------------------------------


    Note to Table 4 of Paragraph (c)(2): 1. CMC (Criteria Maximum 
Concentration) is the water quality criteria to protect against 
acute effects in aquatic life and is the highest instream 
concentration of a priority toxic pollutant consisting of a short-
term average not to be exceeded more than once every three years on 
the average.
    2. CCC (Continuous Criteria Concentration) is the water quality 
criteria to protect against chronic effects in aquatic life and is 
the highest in stream concentration of a priority toxic pollutant 
consisting of a 4-day average not to be exceeded more than once 
every three years on the average.
    3. 1 Q 10 is the lowest one day flow with an average recurrence 
frequency of once in 10 years determined hydrologically.
    4. 1 B 3 is biologically based and indicates an allowable 
exceedence of once every 3 years. It is determined by EPA's 
computerized method (DFLOW model).
    5. 7 Q 10 is the lowest average 7 consecutive day low flow with 
an average recurrence frequency of once in 10 years determined 
hydrologically.
    6. 4 B 3 is biologically based and indicates an allowable 
exceedence for 4 consecutive days once every 3 years. It is 
determined by EPA's computerized method (DFLOW model).


    (iv) If the State does not have such a low flow value below which 
numeric standards do not apply, then the criteria included in paragraph 
(d) of this section apply at all flows.
    (v) If the CMC short-term averaging period, the CCC four-day 
averaging period, or once in three-year frequency is inappropriate for 
a criterion or the site to which a criterion applies, the State may 
apply to EPA for approval of an alternative averaging period, 
frequency, and related design flow. The State must submit to EPA the 
bases for any alternative averaging period, frequency, and related 
design flow. Before approving any change, EPA will publish for public 
comment, a document proposing the change.
    (3) The freshwater and saltwater aquatic life criteria in the 
matrix in paragraph (b)(1) of this section apply as follows:
    (i) For waters in which the salinity is equal to or less than 1 
part per thousand 95% or more of the time, the applicable criteria are 
the freshwater criteria in Column B;
    (ii) For waters in which the salinity is equal to or greater than 
10 parts per thousand 95% or more of the time, the applicable criteria 
are the saltwater criteria in Column C except for selenium in the San 
Francisco Bay estuary where the applicable criteria are the freshwater 
criteria in Column B (refer to footnotes p and q to the table in 
paragraph (b)(1) of this section); and
    (iii) For waters in which the salinity is between 1 and 10 parts 
per thousand as defined in paragraphs (c)(3)(i) and (ii) of this 
section, the applicable criteria are the more stringent of the 
freshwater or saltwater criteria. However, the Regional Administrator 
may approve the use of the alternative freshwater or saltwater criteria 
if scientifically defensible information and data demonstrate that on a 
site-specific basis the biology of the water body is dominated by 
freshwater aquatic life and that freshwater criteria are more 
appropriate; or conversely, the biology of the water body is dominated 
by saltwater aquatic life and that saltwater criteria are more 
appropriate. Before approving any change, EPA will publish for public 
comment a document proposing the change.
    (4) Application of metals criteria. (i) For purposes of calculating 
freshwater aquatic life criteria for metals from the equations in 
paragraph (b)(2) of this section, for waters with a hardness of 400 mg/
l or less as calcium carbonate, the actual ambient hardness of the 
surface water shall be used in those equations. For waters with a 
hardness of over 400 mg/l as calcium carbonate, a hardness of 400 mg/l 
as calcium carbonate shall be used with a default Water-Effect Ratio 
(WER) of 1, or the actual hardness of the ambient surface water shall 
be used with a WER. The same provisions apply for calculating the 
metals criteria for the comparisons provided for in paragraph 
(c)(3)(iii) of this section.
    (ii) The hardness values used shall be consistent with the design 
discharge conditions established in paragraph (c)(2) of this section 
for design flows and mixing zones.
    (iii) The criteria for metals (compounds #1--#13 in the table in 
paragraph (b)(1) of this section) are expressed as dissolved except 
where otherwise noted. For purposes of calculating aquatic life 
criteria for metals from the equations in footnote i to the table in 
paragraph (b)(1) of this section and the equations in paragraph (b)(2) 
of this section, the water effect ratio is generally computed as a 
specific pollutant's acute or chronic toxicity value measured in water 
from the site covered by the standard, divided by the respective acute 
or chronic toxicity value in laboratory dilution water. To use a water 
effect ratio other than the default of 1, the WER must be determined as 
set forth in Interim Guidance on Determination and Use of Water Effect 
Ratios, U.S. EPA Office of Water, EPA-823-B-94-001, February 1994, or 
alternatively, other scientifically defensible methods adopted by the 
State as part of its water quality standards program and approved by 
EPA. For calculation of criteria using site-specific values for both 
the hardness and the water effect ratio, the hardness used in the 
equations in paragraph (b)(2) of this section must be determined as 
required in paragraph (c)(4)(ii) of this section. Water hardness must 
be calculated from the measured calcium and magnesium ions present, and 
the ratio of calcium to magnesium should be approximately the same in 
standard laboratory toxicity testing water as in the site water.
    (d)(1) Except as specified in paragraph (d)(3) of this section, all 
waters assigned any aquatic life or human health use classifications in 
the Water Quality Control Plans for the various Basins of the State 
(``Basin Plans'') adopted by the California State Water Resources 
Control Board (``SWRCB''), except for ocean waters covered by the Water 
Quality Control Plan for Ocean Waters of California (``Ocean Plan'') 
adopted by the SWRCB with resolution Number 90-27 on March 22, 1990, 
are subject to the criteria in paragraph (d)(2) of this section, 
without exception. These criteria apply to waters identified in the 
Basin Plans. More particularly, these criteria apply to waters 
identified in the Basin Plan chapters designating beneficial uses for 
waters within the region. Although the State has adopted several use 
designations for each of these waters, for purposes of this action, the 
specific standards to be applied in paragraph (d)(2) of this section 
are based on the presence in all waters of some aquatic life 
designation and the presence or absence of the MUN use designation 
(municipal and domestic supply). (See Basin Plans for more detailed use 
definitions.)
    (2) The criteria from the table in paragraph (b)(1) of this section 
apply to the water and use classifications defined in paragraph (d)(1) 
of this section as follows:

[[Page 31719]]



------------------------------------------------------------------------
      Water and use classification             Applicable criteria
------------------------------------------------------------------------
(i) All inland waters of the United      (A) Columns B1 and B2--all
 States or enclosed bays and estuaries    pollutants
 that are waters of the United States    (B) Columns C1 and C2--all
 that include a MUN use designation.      pollutants
                                         (C) Column D1--all pollutants
------------------------------------------------------------------------
(ii) All inland waters of the United     (A) Columns B1 and B2--all
 States or enclosed bays and estuaries    pollutants
 that are waters of the United States    (B) Columns C1 and C2--all
 that do not include a MUN use            pollutants
 designation.                            (C) Column D2--all pollutants
------------------------------------------------------------------------

    (3) Nothing in this section is intended to apply instead of 
specific criteria, including specific criteria for the San Francisco 
Bay estuary, promulgated for California in the National Toxics Rule at 
Sec. 131.36.
    (4) The human health criteria shall be applied at the State-adopted 
10 (-6) risk level.
    (5) Nothing in this section applies to waters located in Indian 
Country.
    (e)Schedules of compliance. (1) It is presumed that new and 
existing point source dischargers will promptly comply with any new or 
more restrictive water quality-based effluent limitations (``WQBELs'') 
based on the water quality criteria set forth in this section.
    (2) When a permit issued on or after May 18, 2000 to a new 
discharger contains a WQBEL based on water quality criteria set forth 
in paragraph (b) of this section, the permittee shall comply with such 
WQBEL upon the commencement of the discharge. A new discharger is 
defined as any building, structure, facility, or installation from 
which there is or may be a ``discharge of pollutants'' (as defined in 
40 CFR 122.2) to the State of California's inland surface waters or 
enclosed bays and estuaries, the construction of which commences after 
May 18, 2000.
    (3) Where an existing discharger reasonably believes that it will 
be infeasible to promptly comply with a new or more restrictive WQBEL 
based on the water quality criteria set forth in this section, the 
discharger may request approval from the permit issuing authority for a 
schedule of compliance.
    (4) A compliance schedule shall require compliance with WQBELs 
based on water quality criteria set forth in paragraph (b) of this 
section as soon as possible, taking into account the dischargers' 
technical ability to achieve compliance with such WQBEL.
    (5) If the schedule of compliance exceeds one year from the date of 
permit issuance, reissuance or modification, the schedule shall set 
forth interim requirements and dates for their achievement. The dates 
of completion between each requirement may not exceed one year. If the 
time necessary for completion of any requirement is more than one year 
and is not readily divisible into stages for completion, the permit 
shall require, at a minimum, specified dates for annual submission of 
progress reports on the status of interim requirements.
    (6) In no event shall the permit issuing authority approve a 
schedule of compliance for a point source discharge which exceeds five 
years from the date of permit issuance, reissuance, or modification, 
whichever is sooner. Where shorter schedules of compliance are 
prescribed or schedules of compliance are prohibited by law, those 
provisions shall govern.
    (7) If a schedule of compliance exceeds the term of a permit, 
interim permit limits effective during the permit shall be included in 
the permit and addressed in the permit's fact sheet or statement of 
basis. The administrative record for the permit shall reflect final 
permit limits and final compliance dates. Final compliance dates for 
final permit limits, which do not occur during the term of the permit, 
must occur within five years from the date of issuance, reissuance or 
modification of the permit which initiates the compliance schedule. 
Where shorter schedules of compliance are prescribed or schedules of 
compliance are prohibited by law, those provisions shall govern.
    (8) The provisions in this paragraph (e), Schedules of compliance, 
shall expire on May 18, 2005.

[FR Doc. 00-11106 Filed 5-17-00; 8:45 am]
BILLING CODE 6560-50-P