[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]


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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.

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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 
0.063 <greek-m>g/L more than once every three years on the average 
and if the one-hour average concentration does not exceed 0.46 
<greek-m>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 
<greek-m>g/L more than once every three years on the average and if 
the one-hour average concentration does not exceed 0.37 <greek-m>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]
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