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 This website is no longer updated and links to external websites and some internal pages may not work.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

Section 404 of the Clean Water Act

Memorandum: Assessment of Stream Ecosystem Structure and Function under Clean Water Act Section 404 Associated with Review of Permits for Appalachian Surface Coal Mining

This document clarifies the agencies’ interpretation of current regulatory requirements at 40 CFR 230.11(e) for determining “the nature and degree of effect that the proposed discharge will have…on the structure and function of the aquatic ecosystem and organisms.”

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