The Environmental Protection Agency (EPA) is announcing the release of Ambient Water Quality Criteria to Address Nutrient Pollution in Lakes and Reservoirs. These national recommended criteria are models for total nitrogen and total phosphorus concentrations in lakes and reservoirs to protect three different designated uses—aquatic life, recreation, and drinking water source protection—from the adverse effects of nutrient pollution. Nutrient pollution can degrade the conditions of water bodies worldwide, and the effects of excess nitrogen and phosphorus may be particularly evident in lakes and reservoirs. These recommended criteria are based on stressor-response models, which link nutrient pollution stressors (nitrogen, phosphorus) to responses associated with protection of designated uses. Models and associated criteria provided in this document are based on national data. States and authorized tribes can also incorporate local data, when available, into the national models, helping states and authorized tribes to derive numeric nutrient criteria that apply relationships estimated from national data while accounting for unique local conditions. These recommended criteria replace numeric nutrient criteria recommended by EPA in 2000 and 2001 for lakes and reservoirs for 12 out of 14 ecoregions of the conterminous United States. This document was released for 60-day public comment in the Federal Register on May 22, 2020. The comment period was extended 30 days, for a total comment period of 90 days. EPA has considered the comments, made minor revisions to the draft document in response, and published this final document to provide recommendations for states and authorized tribes interested in establishing water quality standards under the Clean Water Act (CWA) to protect the designated uses of their lakes and reservoirs from nutrient pollution.

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