In 1998, EPA published a Numeric Nutrient Strategy describing the approach the Agency would follow to develop nutrient information and work with the states and tribes to help them adopt numeric nutrient criteria into their water quality standards.

• Numeric Nutrient Criteria Strategy (PDF) (53 pp, 271 K)
• Numeric Nutrient Criteria Fact Sheet

In 2001, EPA wrote a memo to states and authorized tribes that provided additional guidance for developing nutrient criteria plans and describing the role of the plans, the flexibility available to states and tribes, and EPA’s expectations for the time frame in which states and tribes should develop a plan and adopt nutrient criteria into their water quality standards.

• Development and Adoption of Nutrient Criteria into Water Quality Standards (November 2001 EPA Memo) (PDF) (21 pp, 67 K)

Then, in 2007, EPA published a memo providing a national update on the development of numeric nutrient water quality standards and described EPA’s commitment to accelerating the pace of state and tribal progress.

• Nutrient Pollution and Numeric Water Quality Standards (May 2007 EPA Memo) (PDF) (8 pp, 132 K)

In 2008, EPA published "State Adoption of Numeric Nutrient Standards 1998–2008". This document was the first national report on progress made by the states in adopting numeric nutrient water quality standards (WQS). In recognition of the urgency of addressing nitrogen and phosphorus pollution, EPA formed the Nutrient Innovations Task Group (NITG) to focus on reducing nitrogen and phosphorus pollution in U.S. waters. In 2009, the NITG published a report to draw public attention to the need for nutrient reduction strategies.

• An Urgent Call to Action: Report of the State-EPA Nutrient Innovations Task Group
• Nutrient Innovations Task Group, Report Fact Sheet

In 2011, EPA published a comprehensive memorandum reaffirming its commitment to partnering with states and stakeholders to address nitrogen and phosphorus pollution. This memorandum presents a framework that states can use to reduce nitrogen and phosphorus pollution while developing numeric criteria.

• Working in Partnership with States to Address Phosphorus and Nitrogen Pollution through Use of a Framework for State Nutrient Reductions (March 2011 EPA Memo)

In 2016, EPA reaffirmed its commitment to support states and stakeholders to collaborate in reducing nutrient pollution. This memo announces support for state planning or implementation of watershed-based, multi-stakeholder projects to reduce public health impacts from nitrates in drinking water sources and from nitrogen and phosphorus pollution contributing to harmful algal blooms in water bodies.

• Renewed Call to Action to Reduce Nutrient Pollution and Support for Incremental Actions to Protect Water Quality and Public Health (September 2016 EPA Memo)