[Federal Register Volume 62, Number 152 (Thursday, August 7, 1997)] [Notices] [Page 42554] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 97-20975] ----------------------------------------------------------------------- ENVIRONMENTAL PROTECTION AGENCY [OW-FRL-5872-5] Water Quality Criteria; Ambient Water Quality Criteria AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of Ambient Water Quality Criteria Document for Tributyltin (TBT) and Request for Comments. ----------------------------------------------------------------------- SUMMARY: The Environmental Protection Agency (EPA) announces the availability for public comment of an ambient water quality criteria document for tributyltin (TBT). This document contains ambient water quality criteria for the protection of aquatic organisms and their uses. These criteria are guidance to States and others, and in themselves have no binding legal effect. When published in final form, these criteria may form the basis for enforceable State water quality standards. These TBT criteria are published pursuant to Section 304(a)(1) of the Clean Water Act. DATES: Written comments should be submitted to the person listed directly below by October 6, 1997. ADDRESSES: This notice contains a summary of the criteria document for tributyltin (TBT). Copies of the complete document may be obtained from: U.S. Environmental Protection Agency , National Center for Environmental Publications and Information, 11029 Kenwood Road, Cincinnati, Ohio 45242, phone (513) 489-8190 fax (513) 489-8695. FOR FUTHER INFORMATION CONTACT: Comments should be sent to: Dr. Frank Gostomski, Health and Ecological Criteria Division (4304), Office of Science and Technology, Office of Water, U.S. Environmental Protection Agency, 401 M Street SW, Washington, DC 20460. SUPPLEMENTARY INFORMATION: Background Section 304 (a) (1) of the Clean Water Act [33 U.S.C. 1314 (a) (1)] requires EPA to publish and periodically update ambient water quality criteria. These criteria are to reflect the latest scientific knowledge on the identifiable effects of pollutants on public health and welfare, aquatic life and recreation. When published in final form, EPA water quality criteria may form the basis for enforceable State water quality standards. Criteria Document EPA previously issued an ambient water quality criteria document for TBT for public comment on June 1, 1989 [54 FR 23529]. EPA also issued a notice of availability of additional toxicity data for TBT on October 25, 1989 [54 FR 43482]. Today's ambient water quality criteria document for TBT was developed by EPA after consideration of public comment on the 1989 draft criteria and an updated literature search that EPA conducted in January, 1997. EPA intends to issue a final TBT ambient water quality criteria document after consideration of public comment. Dated: August 1, 1997. Robert Perciasepe, Assistant Administrator for Water. Appendix A--Summary of Ambient Water Quality Criteria for TBT Freshwater Aquatic Life The procedures described in the ``Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses'' indicate that, except possibly where a locally important species is very sensitive, freshwater aquatic life and their uses should not be affected unacceptably if the four-day average concentration of tributyltin does not exceed 0.063g/L more than once every three years on the average and if the one-hour average concentration does not exceed 0.46 g/L more than once every three years on the average. Saltwater Aquatic Life The procedures described in the ``Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses'' indicate that, except where a locally important species is very sensitive, saltwater organisms and their uses should not be affected unacceptably if the four-day average concentration of tributyltin does not exceed 0.010 g/L more than once every three years on the average and if the one-hour average concentration does not exceed 0.37 g/L more than once every three years on the average. Implementation As discussed in the Water Quality Standards Regulation (40 CFR Part 131; 48 FR 51400), a water quality criterion for aquatic life has regulatory effect only after it has been adopted in State water quality standards. Such a criterion for a pollutant is to be set at a level protective of a particular designated use. With the approval of EPA, States designate one or more uses for each body of water or segment thereof and adopt criteria that are protective of the use[s]. In each standard, a State may adopt the national recommended criterion, if one exists, or if adequately justified, a site- specific criterion. Site-specific criteria may include not only site-specific criterion concentrations, but also site-specific, and possibly pollutant-specific, durations of averaging periods and frequencies of allowed excursions. The averaging periods of ``one hour'' and ``four days'' were selected by EPA on the basis of data concerning how rapidly some aquatic species react to increases in the concentrations of some pollutants. It is EPA's best scientific judgment that aquatic ecosystems should not be exposed to contaminants in excess of the criterion more often than once every three years. However, various species and ecosystems react and recover at greatly differing rates. Therefore, if adequate justification is provided, site-specific and/or pollutant-specific concentrations, durations, and frequencies may be higher or lower than those given in national water quality criteria for aquatic life. Use of criteria, which have been adopted in state water quality standards, for developing water quality-based permit limits and for designing waste treatment facilities requires selection of an appropriate wasteload allocation model. Although dynamic models are preferred for the application of these criteria, limited data or other considerations might require the use of a steady-state model. Guidance on mixing zones and the design of monitoring programs is also available through EPA. [FR Doc. 97-20975 Filed 8-6-97; 8:45 am] BILLING CODE 6560-50-P