Nitrogen and phosphorus (or nutrient) pollution is a leading cause of water quality impairments in the U.S. As a consequence, EPA has made protecting and restoring the nation's waters from nitrogen and phosphorus pollution a top priority. This priority was most recently articulated in a memorandum from EPA Assistant Administrator for Water, Benjamin Grumbles, in May 2007 to State, Great Water Body, Interstate, and authorized Tribal Water Programs. During the past ten years, EPA has worked in partnership with States, Territories, authorized Tribes and certain River Basin Commissions to adopt numeric nutrient criteria into water quality standards. These standards are critical for preventing the harmful effects of nitrogen and phosphorus pollution in the nation's waters and for restoring water quality from the impairments caused by this pollution.

"EPA-821-F-08-007." "December 2008."

Purpose of the Report -- Scope of the Nitrogen and Phosphorus Pollution Problem -- Why Numeric Nutrient Standards are Important -- Measuring Progress and Reporting Results -- What States Have Achieved.