The National Water Quality Inventory Report to Congress (305(b) report) draws from two complementary sources of information on water quality. First, it summarizes the results of the statistically-representative National Aquatic Resource Surveys (NARS) conducted by the EPA in partnership with state and tribal water quality agencies. Second, it provides a tally of the local, site-specific assessment results reported by states in the Integrated 303(d)/305(b) Reports submitted biennially to EPA and loaded into the Assessment and Total Maximum Daily Load Tracking and Implementation System (ATTAINS) database.

• National Water Quality Inventory Report to Congress (PDF)(22 pp, 1 MB)