The U.S. EPA's National Water Quality Inventory: 2000 Report to Congress cites nutrients (nitrogen and phosphorus) as one of the leading causes of water quality impairment in our Nation's rivers, lakes and estuaries. If a waterbody is impaired, it means it is not safe for everyday human uses -- fishing, swimming, and other normal activities.
Despite the scale of the water quality problem, no national water quality criteria exist for nutrients. However, the US EPA recently developed national criteria guidance documents and the states must soon incorporate nutrient criteria into their water quality standards.
