Big Raccoon-Wabash River Watershed TMDL Project

The Big Raccoon-Wabash River Watershed was selected by the Indiana Department of Environmental Management for the development of a Total Maximum Daily Load report. A Total Maximum Daily Load (TMDL) is classified as the amount of a pollutant that a body of water can intake while still meeting water quality standards. The TMDL report includes additional information as well, including an overview of water quality data, a physical description of the watershed, potential sources of pollution, the loading capacity (TMDL) for each pollutant, reduction standards for each pollutant needed to meet water quality standards, as well as suggestions for potential implementation practices. The goal of a TMDL report is to determine the loading capacity of a waterbody, then to allocate that load among different pollutant sources in order to enact appropriate control measures and achieve water quality standards. Additional information regarding the TMDL program and the TMDL process can be found on our  TMDL Reports  webpage and the  Nonpoint Source Program/TMDL Program Story Map .

The Big Raccoon-Wabash River watershed has been prioritized for TMDL development due to existing impairments and the interest in using TMDL data and analysis to develop a Watershed Management Plan.

The Big Raccoon-Wabash River watershed is located in western Indiana and the watershed covers approximately 74 square miles in Parke County. Subwatersheds in Big Raccoon-Wabash River included in the Total Maximum Daily Load (TMDL) report are Cat Creek-Leatherwood Creek, Rocky Run-Leatherwood Creek, Rock Run-Big Raccoon Creek, and Town of Mecca-Big Raccoon Creek.

Previous surveys of the Big Raccoon-Wabash River watershed indicated impairments significant enough for the watershed to be listed on the Indiana Department of Environmental Management 303(d) List of Impaired Waters.

Impairments currently identified in the watershed include E. coli, polychlorinated biphenyls (PCBs) in fish tissue, and impaired biotic communities (IBC). Historic sampling revealed approximately 90 miles of impaired streams in the Big Raccoon-Wabash River watershed; However, it is suspected that additional stream miles may be impaired since much of the watershed is currently unassessed.

Potential pollution sources that may be contributing to these impairments include nonpoint sources from agricultural lands, pastures, rural run-off, wildlife, as well as point sources from developed land such as straight pipe discharges and home sewage treatment. Data analysis for the TMDL report will further reveal the most likely pollutant sources in the Big Raccoon-Wabash River watershed.  

Conducive to determining the current water conditions and extent of impairments in the Big Raccoon-Wabash River watershed, a watershed characterization study will be enacted beginning November 2022 and end October 2023. Sampling selection sites were elected based on a geometric progression of drainage areas, beginning at the mouth of Big Raccoon Creek, also known as a pour point, and progressing upstream through tributaries to the primary headwaters. Monitoring sites were then placed at the closest bridge or crossroads, providing easy stream access in order to conduct safe and efficient sampling. Starting November 2022 select pour sites at the base of each 12-digit subwatershed will be sampled monthly for general water chemistry and nutrient parameters. From April 2023 through October 2023 all monitoring sites will be sampled monthly for general water chemistry, nutrient parameters, and E. coli. All monitoring sites are also sampled during the summer months to account for biological impairments by observing fish and macroinvertebrate communities. There are 18 total sampling sites for the Big Raccoon-Wabash River watershed characterization study including 6 pour point sites. These selected pour sites are sites T01, T06, T07, T11, T12, and T16.

 2023 Big Raccoon-Wabash River Watershed Sampling and Analysis Workplan 

 IDEM Surface Water Results Summary Quarter 1 (November 2022-January 2023) 

 IDEM Surface Water Results Summary Quarter 2 (February 2023-April 2023) 

Use the "+" and "-" buttons in the lower right corner of the map to explore streams, impairments, monitoring sites, and NPDES permitted facilities within the Big Raccoon-Wabash River watershed. A legend is also available on the left side of the map.