United States
            Environmental Protection
            Agency	
Office of Water
(4303T)
EPA-821-F-02-024
October 2002
             Fact Sheet

Guidelines  Establishing Test Procedures for the
Analysis of Pollutants; Whole Effluent Toxicity Test
Methods;  Final Rule

Summary
EPA is approving revisions to several whole effluent toxicity (WET) test methods that are
currently approved at 40 CFR Part 136.  These methods are for use in Clean Water Act (CWA)
data gathering and compliance monitoring programs.  In addition, this final rule ratifies EPA's
previous approval of ten  WET methods at 40 CFR Part 136 for nationwide use and removes two
other methods from the Part 136 listing.	
Background

In 1995, EPA amended the "Guidelines
Establishing Test Procedures for the Analysis of
Pollutants" to add a series of standardized
whole effluent toxicity (WET) test methods to the
list of methods approved at 40 CFR Part 136
(WET final rule). The WET final rule approved
17 methods for measuring the acute and short-
term chronic toxicity of effluents and receiving
waters to freshwater, marine, and estuarine
organisms.

Several parties filed suit challenging the 1995
rulemaking.  To resolve that litigation, EPA
entered into settlement agreements with them.
This final rule partially fulfills the requirements of
two settlement agreements between EPA and
stakeholders (Edison Electric Institute etal. v.
EPA, Settlement Agreement, July 24, 1998, and
Lone Star Steel v. EPA, Settlement Agreement,
March 4, 1998).

Final Rule

This final rule updates WET test methods, to
makes minor corrections and clarifications, and
addresses specific stakeholder concerns.

Updates include revised method precision
statements that reflect recent variability studies,
incorporation of all previous addenda and errata,
and corrections for additional technical errors
not noted  in previous errata.
        Revisions also address the following specific
        stakeholder concerns:
        •  blocking by known parentage
        •  pH drift
        •  concentration-response relationships
        •  confidence intervals
        •  dilution series selection
        •  dilution water acceptability
        •  pathogen interference

        Lastly, this final rule ratifies ten methods that are
        approved at 40  CFR Part 136 for nationwide use
        and removes two other methods from the Part
        136 listing.

        Additional Information and Copies

        For further information concerning this final rule,
        please contact Marion Kelly at the U.S. EPA
        Office of Water, Engineering and Analysis
        Division (4303), 1200 Pennsylvania Avenue,
        Washington, D.C. 20460; (Email:
        kelly.marion@epa.gov) or Debra Denton at U.S.
        EPA Region 9, c/o SWRCB, 1001 I Street,
        Sacramento, CA 95814 (E-mail:
        denton.debra@epa.gov).

        You may view or download the complete text of
        the Federal Register notice and the revised
        editions of the three supporting WET method
        manuals on the Internet at
        http://www.epa.gov/waterscience/WET.  You
        can find all references cited in the preamble
        through  the Water Docket, EPA West Building,
        Room B135, 1301 Constitution Ave. NW,
        Washington, D.C. 20004; (e-mail: OW-
        docket@epa.gov).

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