An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Northwest Water Quality Temperature Guidance for Salmon, Steelhead and Bull Trout


Water temperature is a critical attribute of the freshwater habitat of Pacific Northwest salmon and trout. Native salmon and trout require cold water for spawning, rearing and migrating.

State and tribal temperature water quality standards play an important role in helping to maintain and restore the cold temperatures of Northwest rivers and streams to protect salmon and trout and aid in their recovery.

Related Documents

Guidance for Pacific Northwest State and Tribal Temperature Water Quality Standards 

The guidance is intended to assist states and tribes in adopting water quality standards for temperature that are consistent with the Clean Water Act and the Endangered Species Act.

Technical Synthesis

The Technical Synthesis, along with the Technical Issue Papers below, summarizes the science and forms the basis for EPA's temperature guidance referenced above. 

Cold-Water Refuges Primer

The Primer is a guide for the identification of cold water refuges, which are features of the thermal regime important to salmon and trout.

Related information:

​Technical Issue Papers

You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.