Methodology for developing Iowa’s 2002 Section 303(d) list of Impaired Waters

(2003) Methodology for developing Iowa’s 2002 Section 303(d) list of Impaired Waters. Natural Resources, Department of

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Abstract

Development of a state Section 303(d) list includes three interrelated program areas of the federal Clean Water Act (CWA): (1) establishment of state water quality standards that identify beneficial uses for the state’s waterbodies and that identify criteria to determine whether the use is being achieved, (2) preparation of the state’s biennial Section 305(b) report by comparing water quality information to water quality criteria to determine whether or not beneficial uses are being achieved, and (3) addition of the appropriate waters assessed as not fully attaining beneficial uses (“impaired”) in the Section 305(b) report to the State’s Section 303(d) list. The 303(d) list is thus a comprehensive public accounting of all impaired waterbodies. An impaired waterbody is one that does not meet water quality standards including designated uses, numeric criteria, narrative criteria, and/or anti-degradation requirements as defined in 40 CFR 131. The violations of water quality standards might be due to an individual pollutant, multiple pollutants, “pollution,” or an unknown cause of impairment.