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| Analytical MethodsUnited States Environmental ProtectionAgencyOffice of Water4303EPA-821-F-01-011September 2001Guidelines Establishing Test Procedures for theAnalysis of Pollutants; Whole Effluent Toxicity TestMethods; Proposed RuleBackground
	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 (60 FR53529; October 16, 1995) (WET final rule).  The WET final rule approved 17 methods for measuring the acute and short-term chronictoxicity of effluents and receiving waters to fresh water, marine, and estuarine organisms. 

	After promulgation, a variety of parties filed suitchallenging the EPA rulemaking.  To resolve that litigation, EPA entered into settlement agreements with the various parties.  This proposed rule, inpart, fulfills the requirements of two settlement agreements between EPA and stakeholders (*Edison Electric Institute et al. v. EPA*, Settlement Agreement, July 24, 1998; *Lone Star Steel v. EPA*, Settlement Agreement, March 4, 1998).
Proposed Rule
This proposed rule would revise WET test methods to update the methods, to provide minor corrections and clarifications, and to address specific stakeholder concerns.  Proposed updates to the methods include revising method precision statements to reflect recent variability studies, incorporating all previous addenda and errata, and correcting additional technical errors not noted inprevious errata.  Proposed revisions also address the following specific stakeholder concerns: blocking by known parent age, pH drift, concentration-response relationships, nominal error rate adjustments, confidence intervals, dilution series selection, dilution water acceptability, and pathogen interference.  Lastly,this proposed rule presents the final results of an interlaboratory variability study of WET test methods and proposes to ratify the previous approval of those methods evaluated in the study.
Additional Information and Copies
	For further information concerning this proposed rule, please contact Marion Kelly at the U.S. EPA, OW, Engineering and Analysis Division (4303T), Ariel Rios Building, 1200 Pennsylvania Ave. N.W.,Washington, D.C.  20460; (e-mail:Kelly.Marion@epa.gov) or Teresa Norberg-King atthe U.S. EPA, ORD, 6201 Congdon Blvd., Duluth, MN 55804-2595; (e-mail:Norberg-King.Teresa@epa.gov).

The complete text of the *Federal Register* notice may be viewed or downloaded on the Internet at http://www.epa.gov/fedrgstr/.  Two supporting documents (*Proposed Changes to Whole Effluent Toxicity Method Manuals (EPA 821-B-01-002)*; and*Final Report: Interlaboratory Variability Study of EPA Short-term Chronic and Acute Whole Effluent Toxicity Test Methods*) are available on the Internet at http://www.epa.gov/waterscience/WET/. All references cited in the preamble can beobtained through the Water Docket, East Tower Basement, Room EB57, 401 M Street, S.W., Washington, D.C. 20460; (e-mail: OW-docket@epa.gov).

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