This update provides guidance to States and Tribes authorized to establish water quality standards under the Clean Water Act (CWA), to protect aquatic life from acute and chronic effects of ammonia. Under the CWA, States and Tribes are to establish water quality criteria to protect designated uses. State and tribal decision makers retain the discretion to adopt approaches on a case-by-case basis that differ from this guidance when appropriate. While this update constitutes EPA’s scientific recommendations regarding ambient concentrations of ammonia that protect freshwater aquatic life, this update does not substitute for the CWA or EPA’s regulations; nor is it a regulation itself. Thus, it cannot impose legally binding requirements on EPA, States, Tribes, or the regulated community, and might not apply to a particular situation based
upon the circumstances. EPA may change this guidance in the future.
This document has been approved for publication by the Office of Science and Technology, Office of Water, U.S Environmental Protection Agency. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.