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Nutrient Management (NM)

Nitrogen and Our Surface Water

Surface Water Quality: Nutrient Criteria for Nitrogen (N)

Protection Agency (EPA) requires states and authorized tribes to develop and publish water quality standards to protect the nation’s waters from over-enrichment associated with human activities. EPA has published nutrient benchmarks to assist states in the development of nutrient standards. Algae in surface waters require N for growth. When other nutrients are adequate, high levels of N in surface waters leads to eutrophication, a condition where high nutrient levels stimulate algal blooms. The primary forms of N that contribute to lowering surface water quality are nitrite, nitrate, ammonium, and organic N. The first three forms are inorganic and are readily available to aquatic vegetation. Organic N gradually becomes available over time. A challenge in developing nutrient criteria is to establish levels that protect water quality but are also achievable at acceptable costs.

Educational Resources

US EPA Nutrient Water Quality Criteria

EPA Summary Table for the Nutrient Criteria Documents

Nutrient Stream Study

Extension Publications

Scientific Review Articles

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National Water Program

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- This material is based upon work supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under Agreement No. 2008-51130-19526.

Photograph by Tom Schultz, Department of Natural Resource Ecology and Management, Iowa State University

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