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 This website is no longer updated and links to external websites and some internal pages may not work.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 »

Impaired Waters and TMDLs

Establishing TMDL "Daily" Loads in Light of the Decision by the U.S. Court of Appeals for the D.C. Circuit

The memorandum clarifies EPA's expectations concerning the appropriate time increment used to express TMDLs following the decision of Friends of the Earth, Inc. v. EPA, et al.

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