Aquatic Life Criterion - Selenium
You will need Adobe Reader to view some of the files on this page. See EPA’s About PDF page to learn more.
What is selenium?
Selenium is a naturally occurring element present in sedimentary rocks, shales, coal and phosphate deposits and soils. There are around 40 known selenium-containing minerals but all are rare and generally occur together with sulfides of metals such as copper, zinc and lead.
Where does selenium enter surface water?
Selenium can be released into water resources by natural sources via weathering and by anthropogenic sources, such as surface mining, coal-fired power plants, and irrigated agriculture.
How does selenium affect aquatic life?
Selenium is a nutritionally essential element for animals in small amounts, but toxic at higher concentrations. Selenium bioaccumulates in the aquatic food chain and chronic exposure in fish and aquatic invertebrates can cause reproductive impairments (e.g., larval deformity or mortality). Selenium can also adversely affect juvenile growth and mortality.
Selenium is also toxic to water fowl and other birds that consume aquatic organisms containing excessive levels of selenium.
Final Aquatic Life Ambient Water Quality Final Criterion for Selenium- Freshwater 2016
EPA’s water quality criterion for selenium provides recommendations to states and tribes authorized to establish water quality standards under the Clean Water Act. This final criterion includes information to help states to develop site specific criteria that account for differing local conditions.
- Fact Sheet: Final Selenium Criterion (June 2016)
- Federal Register: 2016 Selenium Criterion (July 13, 2016)
- Final Criterion: Aquatic Life Ambient Water Quality Criterion for Selenium - Freshwater 2016 (June 30, 2016)
- Response to Public Comment: 2015 Draft Selenium Aquatic Life Criterion (June 30, 2016)
Draft Aquatic Life Chronic Criterion for Selenium in Freshwater
EPA updated the recommended aquatic life water quality chronic criterion for selenium in freshwater on June 30, 2016. Below is the draft criterion that was released for public comment in July 2015.
Once finalized, EPA's water quality criterion for selenium will provide recommendations to states and tribes authorized to establish water quality standards under the Clean Water Act.
- 2015 Draft Criterion: Aquatic Life Ambient Water Quality Criterion for Selenium – Freshwater 2015
- 2014 Draft Document: External Peer Review Draft Aquatic Life Ambient Water Quality Criterion for Selenium- Freshwater 2014
- Peer Review Comments: on 2014 External Peer Review Draft Aquatic Life Ambient Water Quality Criterion for Selenium- Freshwater
- Response to Peer Review Comment: on 2014 External Peer Review Draft Aquatic Life Ambient Water Quality Criterion for Selenium- Freshwater
- Response to Public Comment: on 2014 External Peer Review Draft Aquatic Life Amberint Water Quality Criterion for Selenium- Freshwater (July 2016)
- View public comments and other supporting documents on regulations.gov by searching for Docket Number EPA-HQ-OW-2004-0019