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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 taking into account 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.

These requirements were met for the 2008 cycle by the submission of Indiana's 2008 IR to the U.S. EPA and the subsequent approval of Indiana's 2008 303(d) list by that agency.

Since U.S. EPA’s partial approval of Indiana’s 2010 303(d) list in 2013, IDEM has submitted updated 303(d) lists for the 2012, 2014, 2016, and 2018 cycles. More information pertaining to 303(d) lists for the 2008 through 2016 cycles and the draft 208 303(d) list is available upon request by contacting IDEM’s Integrated Report Coordinator.

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.

2018 303(d) List of Impaired Waters Approved by U.S. EPA

IDEM submitted its 2018 finalized 303(d) List of Impaired Waters to U.S. EPA on August 17, 2018 as Appendix I of the 2018 Integrated Report. On May 9, 2019, U.S. EPA notified IDEM that it had consolidated its review of Indiana’s 2012, 2014, 2016, and 2018 303(d) lists. In its approval letter, U.S. EPA concluded that IDEM has met the requirements of Section 303(d) of the federal Clean Water Act and all applicable requirements in the Code of Federal Regulations for all waters submitted on its 303(d) lists to date. However, U.S. EPA has deferred action on certain waters with regard to metals issues that U.S EPA and IDEM have yet to resolve.

Information regarding IDEM’s draft 2018 303(d) list is available upon request by contacting IDEM’s Integrated Report Coordinator.

Appendix I 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.

U.S. EPA Approval of Indiana’s 2018 303(d) List of Impaired Waters

On May 9, 2019, U.S. EPA issued a combined partial approval of IDEM’s 303(d) lists for the 2012 through 2018 cycles.

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