2025 Indian Creek Monroe TMDL Project
An overview of the Indian Creek Monroe Watershed and the TMDL process for identifying and evaluating pollutants
Introduction
Indian Creek Monroe 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 a water can intake while still meeting water quality standards. The TMDL report includes additional information 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, and 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 Indian Creek Monroe 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.
Background
The Indian Creek Monroe Watershed is located southwestern in Greene, Monroe, Martin, and Lawrence counties. The 6 subwatersheds in the Indian Creek Monroe Watershed are Headwaters, Little Indian Creek, Spring Creek, Silverville Branch, Sulphur Creek, and Opossum Creek.
Previous surveys of the Indian Creek Monroe watershed indicated impairments significant enough for the watershed to be listed on the Indiana Department of Enironmental Management 303 (d) List of Impaired Waters.
Impairments currently identified in the watershed include E. coli, polychlorinated biphenyls (PCBs) in fish tissue, mercury in fish tissue, and Impaired biotic communities (IBC). Historic sampling revealed approximately 65 miles of impaired streams in the Indian Creek Monroe Watershed. However, it is suspected that additional stream miles may be impaired since much of the watershed is unassessed.
Potential pollution sources that may be contributing to these impairments include nonpoint sources from agricultural lands, pastures, rural run-off, wildlife, and 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 Indian Creek Monroe Watershed.
Land Use
Indian Creek Monroe Watershed
The Indian Creek Monroe Watershed spans 172 square miles in southwestern Indiana and is located in between Greene, Monroe, Martin, Lawrence Counties. Forest and Hay/Pasture lands primarily dominate land use in this watershed, which accounts for 75% and 13% of the usages. Approximately 6% of this watershed is considered developed, including the municipalities of Owensburg, Williams, and Dover Hill. There are 23 square miles within the watershed in Greene, Martin, and Lawrence counties that are federal land.
Land use data was obtained in 2024 through the cropland data layer developed through the USDA National Agriculture Statistics Service.
1. Headwaters Subwatershed
The Headwaters Subwatershed spans 25.9 square miles and is located in the northern tip of the Indian Creek Monroe Watershed. Forest and Hay/Pasture lands primarily dominate land use in this subwatershed, which accounts for 66% and 22% of usage. Approximately 10% of this subwatershed is considered developed.
Land use data was obtained 2024 cropland data layer developed through the USDA National Agriculture Statistics Service
2. Little Indian Creek Subwatershed
The Little Indian Creek Subwatershed spans 36.2 square miles and is located in the northern tip of the Indian Creek Monroe Watershed. Forest and Hay/Pasture lands primarily dominate land use in this subwatershed, which accounts for 70% and 21% of usage. Approximately 4% of this subwatershed is considered developed.
Land use data was obtained 2024 cropland data layer developed through the USDA National Agriculture Statistics Service
3. Spring Creek Subwatershed
The Spring Creek Subwatershed spans 33.6 square miles and is located in the northern tip of the Indian Creek Monroe Watershed. Forested and Hay/Pasture lands primarily dominate land use in this subwatershed, which accounts for 66% and 23% of usage. Approximately 6% of this subwatershed is considered developed.
Land use data was obtained 2024 cropland data layer developed through the USDA National Agriculture Statistics Service
4. Silverville Branch Subwatershed
The Spring Creek Subwatershed spans 19.7 square miles and is located in the northern tip of the Indian Creek Monroe Watershed. Forested and Hay/Pasture lands primarily dominate land use in this subwatershed, which accounts for 77% and 14% of usage. Approximately 5% of this subwatershed is considered developed.
Land use data was obtained 2024 cropland data layer developed through the USDA National Agriculture Statistics Service
5. Sulphur Creek Subwatershed
The Sulphur Creek Subwatershed spans 30.7 square miles and is located in the northern tip of the Indian Creek Monroe Watershed. Forested lands is the primarily dominate land use in this subwatershed, which accounts for 88% usage. Approximately 6% of this subwatershed is considered developed.
Land use data was obtained 2024 cropland data layer developed through the USDA National Agriculture Statistics Service
6. Opossum Creek Subwatershed
The Opossum Creek Subwatershed spans 27.6 square miles and is located in the northern tip of the Indian Creek Monroe Watershed. Forested and agricultural lands primarily dominate land use in this subwatershed, which accounts for 74% and 14% of usage. Approximately 5% of this subwatershed is considered developed.
Land use data was obtained 2024 cropland data layer developed through the USDA National Agriculture Statistics Service
Watershed Characterization
Conductive to determining the current water conditions and extent of impairments in the Indian Creek Monroe Watershed. A Watershed characterization study will be enacted beginning November 2024 and end October 2025. Sampling Selection sites were elected based on geometric progression of drainage areas, beginning at the mouth of Indian Creek, as known as a pour point, and progressing upstream through tributaries to primary headwaters.
Monitoring sites were then placed at the closest bridge or crossroads providing east stream access in order to conduct safe and efficient sampling. Starting November 2024, the 6 selected pour points at the base of each 12-digit subwatershed will be sampled monthly for general water chemistry and nutrient parameters. From April 2025 through October 2025 all monitoring sites will be sampled monthly for water chemistry, nutrient parameters, and E. coli. All monitoring sites are sampled during the summer months to account for biological impairments by observing fish and macroinvertebrate community populations. There are 25 total sampling sites including 6 pour point sites. These pour point sites are T01, T04, T11, T16, T21, and T25.
Sampling Results
No Quarterly Reports at this time. Please come back in January 2025 to view the first report.
Monitoring Site Locations with Photos
Site T01
Site T01 is a pour point located on Indian Creek on McBride Bluff Rd in Martin County.
Site T02
Site T02 is located on Opossum Creek on State Road 450 in Martin County.
Site T03
Site T03 is located on Indian Creek on State Road 450 near Trinity Springs in Martin County.
Site T04
Site T04 is a pour point located on Sulphur Creek on Indian Springs Road in Martin County.
Site T06
Site T06 is located on Little Sulphur Creek on Hollow Lane in Martin County.
Site T07
Site T07 is located on Indian Creek-Mt. Olive on Mount Olive Quarry Road in Martin County.
Site T08
Site T08 is located on Sulphur Creek on Valley Avenue in Martin County.
Site T09
Site T09 is located on Sulphur Creek on Misty Road in Martin County.
Site T10
Site T10 is located on Indian Creek-Mt. Olive on Williams Silverville Road in Lawrence County.
Site T11
Site T11 is a pour point located on Indian Creek-Mt. Olive on Williams Silverville Road in Lawrence County.
Site T12
Site T12 is located on Indian Creek on State Road 158 in Lawrence County.
Site T14
Site T14 is located on Indian Creek on Indian Creek Road in Lawrence County.
Site T15
Site T15 is located on Indian Creek on Indian Creek Road in Lawrence County.
Site T16
Site T16 is a pour point located on Indian Creek on Armstrong Station Road in Lawrence County.
Site T17
Site T17 is located on Indian Creek on Boone Hollow Road in Lawrence County.
Site T18
Site T18 is located on Spring Creek on Armstrong Station Road in Lawrence County.
Site T19
Site T19 is located on Indian Creek on State Road 58 in Greene County.
Site T20
Site T20 is located on Spring Creek on State Road 54 in Lawrence County.
Site T21
Site T21 is a pour point located on Indian Creek on State Road 54 in Lawrence County.
Site T23
Site T23 is located on Mitchell Branch on State Road 54 in Greene County.
Site T24
Site T24 is located on Indian Creek on County Road 235 South in Greene County.
Site T25
Site T25 is a pour point located on Indian Creek on Rockeast Road in Greene County.
Site T26
Site T26 is located on Little Indian Creek on Rockeast Road in Greene County.
Site T27
Site T27 is located on Indian Creek on Breeden Road in Monroe County.
Site T28
Site T28 is the final sampling site located on Indian Creek on Harmony Road in Monroe County.
Timeline
July 2024
Public Kick-off meeting held July 2024 at
November 2024
Sampling for water chemistry and nutrient parameters begins at select pour points.
April 2025
Water chemistry, nutrient parameters, and E. coli sampling at all 25 sample sites.
Summer 2025
Fish and macroinvertebrate community sampling begins.
October 2025
Water chemistry, nutrient parameters, and E. coli sampling ends at all 25 sample sites.
2026
Sampling data and additional information retrieved are analyzed to determine current impairments, develop TMDLs for pollutants in each subwatershed, and produce the TMDL report.
Spring/Summer 2026
A Draft TMDL Public Meeting is held in addition to a 30 day public comment period.
Fall 2026
Final TMDL report is submitted to the EPA.
Interactive Map
Use the "+" and "-" buttons in the lower right corner of the map to explore streams, impairments, monitoring sites, and NPDES permit facilities within the Indian Creek Monroe Watershed. A legend is also available on the left side of the map.
Indian Creek Monroe Interactive Map_4
Contact
TMDL Project Manager
Dorothy Henthorn: DHenthor@idem.IN.gov | (317) 308-3235
Watershed Specialist
Kathleen Hagan: KHagan@idem.IN.gov | (317) 308-3197
