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Maria Creek Watershed

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The Maria Creek Watershed covers approximately 97 square miles in southwestern Indiana and is located in Sullivan and Knox counties. The four subwatersheds included in the Total Maximum Daily Load (TMDL) report are Marsh Creek, Headwaters Maria Creek, Tilley Ditch, and Cotton Branch.


Past surveys of the Maria Creek Watershed were conducted in 1993, 1999, 2004, and 2009 which included monitoring for fish communities, macroinvertebrate communities, and water chemistry through several IDEM monitoring programs. Impairments previously identified in the watershed include E. coli, dissolved oxygen (DO), and impaired biotic communities (IBC). Potential pollution sources contributing to these impairments include nonpoint sources from agricultural lands and pastures, rural run-off, wildlife, as well as point sources from straight pipe discharges and home sewage treatment systems.

Parameters To Be Addressed

IDEM completed a comprehensive sampling program in the watershed that was based on the current impairments. A total of 18 sites were assessed for general chemistry, nutrients, habitat, and fish and macroinvertebrate communities. A comprehensive list of all parameters is referenced in the approved work plan. The final TMDL report addresses E. coli and biological communities (IBC) impairments in the watershed.


A public kickoff meeting was held to introduce the project and solicit input on December 10, 2019 from 5:00 PM - 7:00 PM at the Sullivan County Fairgrounds, 1301 E County Road 75 North, Sullivan, IN 47882.

A Water Monitoring Demonstration Field Day was held on October 14, 2020 from 4:00 PM – 6:00 PM at the Emison Mill County Park in Bruceville, IN.

Assessments of the sampling data collected for the watershed characterization have been completed. There are 14 stream segments where additional impairments are identified, including impairments for E. coli, impaired biotic communities (IBC), and dissolved oxygen (DO). A public notice was posted to the Indiana Register on February 14, 2021 to inform stakeholders of the new impairments. Public comments were solicited through May 25, 2021. IDEM received no comments regarding the notice.

A draft TMDL final public meeting was held virtually on July 8, 2021 at 3:00 PM EDT. Representatives from IDEM presented findings on the draft TMDL report and were available to answer questions.

A 30-day public comment period for the draft final TMDL report occurred from July 12, 2021 through August 12, 2021. No comments were received.

The final TMDL report was approved by U.S. EPA on September 14, 2021.

The TMDL Report

Watershed Characterization Monitoring 2019-2020

Supplemental Information

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