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National Pollutant Discharge Elimination System (NPDES) |  |
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Whole Effluent ToxicityWhole Effluent Toxicity (WET) is a term used to describe the aggregate toxic effect of an aqueous sample (e.g., whole effluent wastewater discharge) as measured by an organism's response upon exposure to the sample (e.g., lethality, impaired growth or reproduction). WET tests replicate the total effect and actual environmental exposure of aquatic life to toxic pollutants in an effluent without requiring the identification of the specific pollutants. WET testing is a vital component of the water quality standards implementation through the NPDES permitting process and supports meeting the goals of the Clean Water Act (Section 402), "..maintain the chemical, physical and biological integrity of the nation's waters."Click here to view WET Guidance Documents.
WET Requirements
WET tests are designed to predict the impact and toxicity of effluents discharges from point sources into waters of the U.S. WET limits developed by permitting authorities are included in NPDES permits to ensure that the state or tribal water quality criteria for aquatic life protection (WET) are met. WET monitoring requirements that are representative of the discharge effluent (40 CFR Part 122.44(d)(1)(ii)) are included in NPDES permits to generate WET data used to determine whether reasonable potential for WET has been demonstrated. If reasonable potntial has been demonstrated then a WET limit must be included in the permit (40 CFR Part 122.44(d)(1)(iv) and (v)). WET test results are also used in determining compliance with NPDES WET permit limits. Key ReferencesWET Training Tools: EPA Whole Effluent Toxicity (WET) DVDs (freshwater and saltwater series) - EPA has produced training DVDs on EPA WET test methods and culturing of test organisms and a supplemental training guide to use with the DVDs for each WET test method listed below. These DVD WET materials were produced to be used as an important training tool for EPA Regions, states and private laboratories to use as part of their NPDES WET program implementation. These WET training DVDs provide an overview of EPA's WET test methods promulgated at 40 CFR Part 136. The training DVDs were developed so that permit writers, their permittees and commercial laboratories can have a better understanding of the EPA WET test methods and how to properly conduct them. They are excellent for training new staff and for NPDES WET training courses. However, these training materials are not intended to replace a thorough understanding and reading of the EPA WET test method manuals. The following WET training materials are available for download: NOTE: The download times for these files may be lengthy, depending on the speed of your connection. If the files take more than several minutes to download to your internet browser, please consider right clicking on the URL and selecting 'Save Target As' to save to your computer to reduce the amount of time taken to view the video. EPA Freshwater Series:
EPA Saltwater Series:
To Order WET Test Method Training Materials: WET test method video training packages (electronic copies of supplemental guides and the DVDs), please contact the National Service Center for Environmental Publications (NSCEP) at (800) 490-9198 or nscep@bps-lmit.com. Make sure to include the appropriate WET publication number in your request. For further information or questions, contact Laura Phillips. EPA NPDES WET Contacts:
EPA NPDES WET Guidance Documents: |
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EPA's promulgated 