Big Muddy
The Big Muddy Water Supply Planning Region covers five counties in southern Illinois: Jefferson, Franklin, Williamson, Perry, and Jackson. While the Big Muddy River Watershed also touches small portions of Washington, Marion, Hamilton, Johnson, Union, and Randolph counties, the majority of the watershed lies within this five-county planning region.
Surface water is the primary source of drinking water for the region. The largest source is Rend Lake, which supplies water to nearly 300,000 people across seven counties. Kinkaid Lake is another major source, serving approximately 22,000 residents in Jackson County. The Rend Lake Conservancy District (RLCD) manages Rend Lake’s water system, providing service to 38 wholesale customers (such as municipalities and water districts) and more than 1,300 retail customers. Some of the wholesale customers, in turn, deliver water to communities outside the Big Muddy region.
Groundwater usage is less extensive in this part of Illinois. While there are sand and gravel aquifers in the Mississippi River valley supporting irrigation usage, outside this area, productive aquifers are often limited and local in nature. Bedrock is near the land surface across much of the region and has not been developed except where fractures and interbedded sandstones support aquifer productivity or where few alternative supplies exist. Public supply groundwater usage and other high-capacity groundwater usage are rare across much of the region; in contrast, private wells are common in rural areas outside service areas for existing water distribution infrastructure.”
ISWS is currently conducting a detailed study of both surface water and groundwater resources in the Big Muddy region. This assessment looks not only at current water availability but also at potential vulnerabilities in the future, such as population growth or climate change impacts. To share its findings, ISWS creates interactive story maps that highlight key results from the water availability analysis. A comprehensive technical report will also be published to summarize the data, methods, and results of the study for regional water supply planning purposes.
