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On June 1, 1989, the Environmental Protection Agency issued an ambient water quality criteria document for tributyltin (TBT) for public comment [54 FR 23529]. The EPA also issued a notice of availability of additional toxicity data for TBT on October 25, 1989 [54 FR 43482]. The ambient water quality criteria document for TBT announced on August 7, 1997 [62 FR 42554], was developed by the EPA after consideration of public comment on the 1989 draft criteria, and an updated literature search that EPA conducted in January, 1997. The EPA intends to issue a final TBT ambient water quality criteria document after consideration of public comment.
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 0.063 µg/L more than once every three years on the average and if the one-hour average concentration does not exceed 0.46 µg/L more than once every three years on the average. 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 µg/L more than once every three years on the average and if the one-hour average concentration does not exceed 0.37 µg/L more than once every three years on the average.
A water quality criterion for aquatic life has regulatory effect only after it has been adopted in State water quality standards (40 CFR Part 131; 48 FR 51400). Such a criterion for a pollutant is to be set at a level protective of a particular designated use. With the approval of the 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.
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 the EPA.
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. Written comments should be submitted by October 6, 1997 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.
Federal Register, Volume 62, Number 152, August 07, 1997, p. 42554.
| Marine Environmental Update Bulletin | August 7, 1997 |