Development of Regional Nutrient Criteria and Implications for the Regulated Community

Water quality impairment due to nutrient over-enrichment is a major threat to many of the nation's surface waters. The EPA has made development of nutrient standards to protect the uses and functions of these waters a national priority (EPA, 1998). Establishment of these nutrient criteria must take into account regional differences and waterbody characteristics. EPA has published related guidance documents for development of criteria, as well as ecoregional nutrient criteria documents for lakes and reservoirs and rivers and streams. EPA envisions that these documents will serve as a starting point to develop more precise numeric levels for nutrient parameters needed to protect aquatic life, recreational, or other uses on site-specific or subregion-specific conditions. Work is underway in states across the U.S. to gather data and develop regional nutrient criteria. States currently have until 2004 to develop and adopt regional nutrient criteria and/or adopt EPA recommended criteria. Approaches for development of a database to support development of regional nutrient criteria and methods for criteria development are discussed. Potential implications to dischargers once criteria are developed and adopted are also addressed.