Water Quality: Identification and Remediation of Polluted Waters Impeded by Data Gaps

Pursuant to a congressional request, GAO discussed the data that the Environmental Protection Agency (EPA) and the states have for making critical water quality decisions required by the Clean Water Act, focusing on: (1) the adequacy of the data for identifying waters for states' 303(d) lists; (2) the adequacy of data for developing total maximum daily loads (TMDL) for those waters; and (3) key factors that affect the states' abilities to develop TMDLs.