For the first time, the agency is setting water quality criteria which serve as recommendations to states and tribes for water quality standards for nutrients, including nitrogen and phosphorous. States are expected to adopt or revise their nutrient standards by 2004, based on the new criteria. The new criteria are expected to significantly reduce nutrients in the nation's waterways. In a 1998 water quality report to Congress, nutrients were listed as a leading cause of water pollution. About half of the nation's waters surveyed by states do not adequately support aquatic life because of excess nutrients.
Water pollution is essentially a biological problem.
Chemical measurements are like taking snapshots of the ecosystem, whereas biological measurements are like making a videotape.