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INDOT and Stormwater Quality

INDOT maintains almost 29,800 lane miles of highways, Operation and Maintenance Facilities, Welcome Centers and Rest Areas, and approximately 1,500 construction projects per year. This amount of impervious surface and construction poses a unique challenge to stormwater. Stormwater runoff is a major contributor to water pollution nationwide and one of the great challenges of pollution control.

Day-to-day activities on roadways can add up and cause stormwater pollution:

  • Litter tossed out of vehicles or from uncovered truck loads
  • Leaking oil or other fluids from cars
  • Heavy metals from tires, brakes, and engine wear
  • Sediment from road wear and tear
  • Salt and other winter weather treatments
  • Spills from traffic accidents
  • Construction activities
  • General facility use and maintenance

The following will discuss regulations and actions taken by INDOT to reduce its impact on stormwater pollution.

Construction Stormwater General Permit (CSGP)

The CSGP is a performance-based regulation designed to reduce pollutants that are associated with construction and/or land disturbing activities. The requirements of the Construction CSGP applies to all persons who are involved in construction activity (which includes clearing, grading, excavation and other land-disturbing activities) that results in the disturbance of one (1) acre or more of total land area. If the land-disturbing activity results in the disturbance of less than one (1) acre of total land area but is part of a larger common plan of development or sale, the project must obtain permit coverage under the CSGP.

For questions about INDOT’s CSGP coverage contact the Stormwater Specialists at Information on active projects can also be found at IDEM’s nSITE Explorer.

Post-Construction Stormwater Measures (PCSMs)

INDOT's Municipal Separate Storm Sewer System (MS4) General Permit and the transition from Rule 5 (327 IAC 15-5) to the CSGP in 2021 requires INDOT to address discharges of post-construction stormwater run-off from new development and redevelopment. As areas develop and impervious surfaces increase, the stormwater velocity, quality, and types of pollutants exposed to stormwater can change and increase. INDOT must require PCSMs, where applicable, to reduce pollutants and downstream impact from roadways and new facilities. The following are guidance documents and resources that show how INDOT is addressing PCSMs and stormwater quality.

Design Memorandum 22-22 Post-Construction Stormwater Management
Post-Construction Stormwater Measure Guidance 1-8-2024
PCSM Quick Facts

Maintenance Plan Templates

INDOT Construction Stormwater Training

The Construction Stormwater Training introduces participants to Erosion and Sediment Control regulations and practices through several online modules. The modules and exam require an estimated 8-10 hours for completion. This training is designed for Stormwater Quality Managers and others inspecting INDOT projects but can be taken by anyone interested in learning more about INDOT Stormwater Management.

For more information about the course, registration, renewals, and active status please visit the training course information page here.

Municipal Separate Storm Sewer System (MS4) General Permit

INDOT has been recognized as an MS4 and is required to create goals to reduce its impact on stormwater pollution. The requirements of the MS4 General Permit influence nearly every aspect of INDOT’s operations, from construction projects and their design, operation and maintenance of facilities, employee education, and beyond.

INDOT is required to submit a Stormwater Quality Management Plan (SWQMP) and an Annual Report to IDEM. These are required to show INDOT is working toward the goals in the MS4 General Permit to help protect Indiana’s stormwater run-off from INDOT’s roadways and construction projects.

For further information please contact the MS4 Coordinator at or 855-INDOT4U (463-6848).

For more information on the MS4 General Permit go to IDEM’s website here.

INDOT MS4 Public Notice

Per the requirements in the MS4 permit INDOT will submit a Notice of Intent to notify IDEM of its intent to comply with the requirements of the MS4 General Permit to Discharge stormwater run-off from interstate highways, US Routes and State Roads into watersheds located within the State of Indiana.

SWQMP Annual Reports

INDOT MS4 Partnership Mapping Tool

The MS4 Partnership Mapping Tool is Indiana’s interactive electronic map tool that can be used to explore and view MS4 boundaries adjacent to INDOT Roadways for urban areas, surface waters, day light conveyances, impaired waters, and other data. The MS4 Partnership Mapping Tool is evolving as more data is gathered through the cooperation and partnerships of Indiana’s MS4s

Supplemental Resources

See Something, Smell Something, Say Something

Report Pollution at INDOT4U

Help INDOT and the INDOT Stormwater team find pollution in our right-of-way so that dangerous and toxic discharges can be cleaned up. By reporting a concern, INDOT can improve the safety for our traveling public and environmental health across the state of Indiana.


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