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 This website is no longer updated and links to external websites and some internal pages may not work.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

Technical Support for Numeric Nutrient Water Quality Criteria Development

EPA has developed a number of resources to help states with developing criteria. In March 2011, EPA issued a comprehensive framework to assist states, territories and tribes in addressing nitrogen and phosphorus pollution. With respect to the framework, our goal is to assist in the development of numeric nitrogen and phosphorus criteria, which will help states, territories, and tribes move toward adopting water quality standards for nitrogen and phosphorus. Additionally, EPA has published technical resources, such as technical guidance documents that describe the techniques for developing numeric criteria for nitrogen and phosphorus pollution for different water bodies, technical documents describing ecoregional criteria, online databases and clearinghouses, and data concerning impaired waters and TMDLs.

Draft Updated Ambient Water Quality Criteria Recommendations for Lakes and Reservoirs of the Conterminous United States: Information Supporting the Development of Numeric Nutrient Criteria

EPA requested scientific views on its draft ambient numeric nutrient water quality criteria recommendations for lakes and reservoirs. Scientific views were submitted on (Docket ID No. EPA–HQ–OW–2019-0675). The comment period for this draft document closed on August 20, 2020. The agency is currently reviewing the comments and will consider them as it works to finalize the recommended criteria. Once final, these recommendations will replace those published by EPA in 2000 and 2001 for lakes and reservoirs.

Reference Documents

Other Resources