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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 nine major water management basins and monitors one major basin each year. IDEM staff assess the data collected in each basin the following year.
In addition to agency-collected data, IDEM solicits data through its External Data Framework 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 water quality assessment results are reported to U.S. EPA every two years through the Indiana Integrated Water Monitoring and Assessment Report, which describes the condition of Indiana’s lakes, streams, ground water and its Lake Michigan shoreline.
IDEM submitted its 2014 Integrated Report to U.S. EPA on April 1, 2014. At that time, the public comment period for the 303(d) List of Impaired Waters, which is part of the Integrated Report, was still underway. On September 25, 2015, IDEM submitted an addendum to its 2014 Integrated Report containing revised versions of some files included with IDEM’s April 1, 2014 submittal. These files are marked as “Revised” in the links below and supersede their original versions, which are marked with an asterisk (*). The addendum also added Appendix I, which identifies the changes made to Indiana’s 303(d) list since its April 1, 2014 submittal, comments received by the U.S. EPA and the public on Indiana’s draft 303(d) list along with IDEM’s responses, and the Indiana’s finalized 2014 303(d) List of Impaired Waters.
Indiana’s 2010 Integrated Water Monitoring and Assessment Report and earlier versions are available upon request by contacting IDEM’s Integrated Report Coordinator.