Prairie du Pont Watershed Plan: A Strategy for Western St. Clair County Watersheds

For the last few years, residents, agencies, and organizations have been working to develop strategies for reducing flood impacts and improving the health of water in western St. Clair County, Illinois. 

Communities in this area, such as East St. Louis and Cahokia Heights, are experiencing converging crises: increasing floods from higher intensity rainfalls and runoff, infrastructure that can’t (and isn’t) keeping up, environmental contamination, and systemic racial inequities (and more).

There are many efforts happening in the area toward making positive changes. One was the development of a watershed plan to help identify strategies to address some of the water challenges. Below is a summary of some of the recommended strategies.

If you’d like more detailed information, please visit the Prairie du Pont Watershed Page.

Questions? Contact Water Program Manager, John O’Donnell at or call (618) 566-4451 ex 14. 


Picture a watershed as a large bathtub. When rain falls or snow melts anywhere within this “bathtub,” the water naturally flows towards its lowest point, which can be thought of as the drain. Watersheds, like Prairie du Pont and Judy’s Branch, play a pivotal role in collecting and directing water within a specific region.

Located in southwestern Illinois near the confluence of the Missouri and Mississippi Rivers, water here follows the land, flowing westward and southward from elevated terrains, flowing down steep bluffs into the fertile floodplain known as the American Bottom. This fertile bottomland has attracted settlement for thousands of years from indigenous communities such as the Mississippian Culture through waves of immigration of French, Spanish, Germans, and those from the American South during the Great Migration when the area was an industrial powerhouse in the early 1900s.

The plan first provided a summary profile of the watershed’s characteristics, which helped to inform potential future community needs and how to begin to prioritize challenges and opportunities. Using this information, committees of residents helped develop an overall vision and goals for a community-wide approach to the watersheds’ systems. Based on these goals, four integrated strategies were created to address prevention and projects. 



Water quality concerns, such as stormwater runoff-induced pollution, are common across Illinois. However, the communities in the project area face the more urgent and hazardous problem of repeated and damaging flooding.  The flooding affecting residents is not just from river flooding or overtopping of levees, but from flash flooding from ponding and overflows during rainstorms. The soils in the floodplain cannot hold much water, and the elevation is low and flat, so water cannot easily flow away from flooded areas without sufficient pump systems and well-maintained drainage ditches. 

The floodplain communities also face raw sewage contamination due to combined sanitary and storm sewer overflows, as well as infiltration of water into damaged sanitary sewer pipes in need of critical repairs and updates. This directly impacts the mental and physical well-being of residents, the community, and the environment, exposing them to the health hazard of untreated sewage.

Addressing these issues isn’t just about clean water for the environment; it’s about protecting communities and ensuring a thriving future for the region.

The Strategies

Using the community-developed goals and input as a guideline, a strategy was organized into four systems. 

First and foremost is securing the safety and wellbeing of the people that live within the watershed. Flooding and sewage contamination issues are immediate and pressing needs and must be addressed before further action can be taken. The strategy of Drain & Flow focuses on ensuring water drains effectively and flows efficiently away from homes and businesses in the region. 

  • Separate combined sewers
  • Replace and secure Pump Stations & Lift Stations
  • Repair & Replace Culverts and abandoned sewer laterals

Projects and practices for holding the water for short periods of time in detention basins and restored wetlands allows for increased capacity to hold and capture floodwaters and sediments in easily maintainable locations as opposed to filling up the ditches and canals of the floodplain. 

  • New Basins in Priority Areas (Above and below bluffs)
  • Restore and expand Wetlands (Marybell, Mullens Slough, Spring Lake)

Slow & Spread strategies are focused on upland communities. This strategy recommends actions based on a stream assessment and feedback from stakeholders, including impervious surface reduction and others. Slowing down the water provides an opportunity to let sediment in streams slow and stay upstream instead of rushing down the bluffs and clogging the lowland systems. 

  • Hard Surface reduction upstream (e.g., pervious pavement at Metrolink and other large lots)
  • Streambank restoration, stabilization, and terracing upstream of the American Bottom
  • Living Streets program expanding buffers and tree canopy along major roads

Short & long-term policy and practices aimed at ensuring future development in and above the floodplain does not increase water pollution or flooding problems for those living here.

  • Stormwater Retention requirements for new developments
  • Elevated new construction requirements
  • Ordinances to protect downstream communities from upstream developments
  • Anti-Dumping enforcement


There is an immediate and long-term need for effective oversight and communication between different levels of government and municipalities within the watershed and for a more structured and organized method for implementing this and other plans and projects addressing the needs for maintenance and planning for the whole of the Prairie du Pont and Judy’s Branch watersheds. Two committees were established as part of the planning process and our hope is they continue to meet and provide needed oversight of continuing work in the area.

  • Resident-led oversight committee
    • Monitor implementation of new projects by local, state, and federal projects
    • Knowledge dissemination to other residents by the committee
  • Technical Advisory Committee continuation
    • Continue coordinating financial expenditures
    • Continue ensuring the technical accuracy of proposed solutions

What’s Next?

HeartLands Conservancy, parallel to the development of the plan, worked with a resident committee to develop a priority list of demonstration projects for funding under IEPA and USEPA grants. Work began on that list of projects in 2023. Smoke Testing of 26,250 linear feet of sanitary sewer and Televising of 34,300 linear feet of storm sewer was completed in 2023, and further projects related to repairs of sewer lines based on those results are planned for 2024 by HLC and partners.

There are many other projects happening in the watershed beyond this plan because of the organized efforts of residents. 

For more detailed information on the Prairie du Pont & Judy’s Branch Watershed Plan, please visit the project webpage here.