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Section 303(d) List of Impaired Waters

The IDEM Office of Water Quality (OWQ) develops Indiana's 303(d) List of Impaired Waters as part of the state's Integrated Water Monitoring and Assessment Report (IR), which is submitted to the U.S. EPA every two years in accordance with Sections 305(b) and 303(d) of the Clean Water Act (CWA).

CWA Section 305(b) requires states to make water quality assessments and provide water quality reports to the U.S. EPA, and CWA Section 303(d) requires states to identify waters through their Section 305(b) water quality assessments, that do not or are not expected to meet applicable state water quality standards with federal technology based standards alone. Under CWA Section 303(d), states are also required to develop a priority ranking for these waters considering the severity of the pollution and the designated uses of the waters. Once this listing and ranking of impaired waters is completed, states are required to develop Total Maximum Daily Loads (TMDLs) for these waters in order to achieve compliance with the water quality standards.

Indiana’s 2022 303(d) List of Impaired Waters

On January 14, 2022, IDEM published Indiana’s draft 2022 303(d) list and the Consolidated Assessment and Listing Methodology (CALM) in the Indiana Register for a 45-day public comment period, which ended on February 28, 2022. IDEM received no comments from the public during this time.

IDEM presented the 2022 303(d) List of Impaired Waters to the Indiana Environmental Rules Board in a virtual public meeting on February 9, 2022.

On April 1, 2022, IDEM uploaded its 2022 Integrated Report, including its finalized 2022 303(d) List of Impaired Waters to U.S. EPA’s Assessment and Total Maximum Daily Load Tracking and Implementation System (ATTAINS) online.

Appendix L of the 2022 Integrated Water Monitoring and Assessment Report includes the 303(d) List (Category 5 of Indiana’s Consolidated List) and Category 4 waters, which are those that are impaired but do not require a Total Maximum Daily Load. Combined, these categories include all known impairments to Indiana waters:

General information on the 303(d) list is available on the Section 303(d) List Frequently Asked Questions page. You may also contact the Integrated Report Coordinator with any questions you have regarding the 303(d) list or to obtain files for previous listing cycles.

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