Ambient Water Quality Criteria Recommendations: Information Supporting the Development of State and Tribal Nutrient Criteria for Rivers and Streams in Nutrient Ecoregion IX

This document presents EPA's nutrient criteria for Rivers and Streams in Nutrient Ecoregion IX. These criteria provide EPA's recommendations to States and authorized Tribes for use in establishing their water quality standards consistent with section 303 (c) of CWA. Under section 303(c) of the CWA, States and authorized Tribes have the primary responsibility for adopting water quality standards as State or Tribal law or regulation. The standards must contain scientifically defensible water quality criteria that are protective of designated uses. EPA's recommended section 304(c) criteria are not laws or regulations - they are guidance that States and Tribes may use as a starting point for the criteria for their water quality standards.