Freshwater and Marine Organisms
This manual describes test procedures for effluents and receiving waters and includes guidelines on test species selection and mobile toxicity test laboratory design. The acute toxicity tests generally involve exposure of any of 20 test organisms to each of five effluent concentrations and a control water. The test duration ranges from 24 to 96 hours.
The methods are approved under Clean Water Act section 304(h) and specified at 40 CFR 136.3, Table I A.
Errata sheet (2016)
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Whole Effluent Toxicity Methods Errata Sheet (PDF)(28 pp, 534 K,
December 2016,
821-R-02-012-ES)
Corrections and clarifications to three WET methods manuals; promulgated as part of the 2017 Clean Water Act Methods Update Rule (August 28, 2017).
- Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms; 5th ed. (PDF)(275 pp, 4 MB, October 2002, 821-R-02-012)