Water Quality: EPA Should Improve Guidance and Support to Help States Develop Standards That Better Target Cleanup Efforts

Water quality standards comprise designated uses and water quality criteria. These standards are critical in making accurate, scientifically based determinations about which of the nation's waters are most in need of cleanup. GAO examined the extent to which (1) states are changing designated uses when necessary, (2) EPA is assisting states toward that end, (3) EPA is updating the "criteria documents" states use to develop the pollutant limits needed to measure whether designated uses are being attained, and (4) EPA is assisting states in establishing criteria that can be compared with reasonably obtainable monitoring data.