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Section 305(b) of the Clean Water Act (CWA) requires the Indiana Department of Environmental Management (IDEM) to assess and report on whether Indiana waters support the beneficial uses designated in Indiana’s water quality standards. IDEM’s CWA Section 305(b) assessments are made in accordance with IDEM’s Consolidated Assessment and Listing Methodology (CALM) by comparing existing and readily available water quality data to the applicable water quality criteria in the State’s water quality standards.
The large majority of the data IDEM uses in its 305(b) assessments are collected by IDEM staff using a rotating basin approach. IDEM has divided Indiana into five major water management basins, monitoring one major basin each year. IDEM staff assess the data collected in each basin within the following year.
In addition to agency-collected data, IDEM uses data from external organizations and agencies, including the United States Geological Survey, Indiana University’s School of Public and Environmental Affairs, and the Indiana State Department of Health. IDEM also solicits water quality data from other colleges, universities and local organizations, such as county health departments, watershed management groups and cities and towns.
IDEM’s assessment results are reported to U.S. EPA through the Indiana Integrated Water Monitoring and Assessment Report every two years, which describes the condition of Indiana’s lakes, streams, ground water and Lake Michigan shoreline.
Indiana’s 2010 Integrated Water Monitoring and Assessment Report (as well as earlier versions) is available upon request by contacting IDEM’s Integrated Report Coordinator (known also as the 303(d)/305(b) Programs Coordinator).