Numeric Nutrient Water Quality Criteria
During the past two decades EPA has encouraged states and tribes to adopt numeric nutrient criteria as an approach to reduce nutrient pollution. As part of this effort, EPA’s National Numeric Nutrient Criteria Program has developed policies, guidance, provided technical and financial support for criteria development, and encouraged state and tribal collaboration and accountability through publicly sharing their plans and progress in adopting numeric nutrient criteria.
The inception, development, and progress made at the national level to reduce nutrient pollution through adoption of numeric nutrient criteria is summarized in the programmatic information on this page. It contains EPA’s Numeric Nutrient Criteria Strategy, accompanying memos, state status adoption reports and recommendations on how to implement additional nutrient reduction strategies.
Numeric nutrient criteria are quantitative expressions of water quality management goals. To assist states in the development and adoption of numeric nutrient criteria, EPA has developed and published technical resources such as factsheets, technical guidance documents, and ecoregional criteria recommendations. These documents address the rationale and scientific basis for dual control of nitrogen and phosphorus, describe and illustrate the main approaches that can be used in criteria development and provide interested states with numeric thresholds that can be adopted as criteria.
EPA has developed an interactive website to show state progress on developing numeric nutrient criteria. The site features maps and tables showing development of nitrogen and phosphorus criteria from 2016 projected through 2019. It also includes each state's existing numeric criteria and development plans. EPA will update this website with new information as it becomes available.