American Bottoms: Regional Demands
How is water used in the American Bottoms Region?
The Illinois State Water Survey (ISWS) calculates water use (demand) primarily using reported data to the Illinois Water Inventory Program (IWIP), although additional analyses were used to calculate agricultural demand. Reported demands to IWIP are constantly being updated for quality assurance and quality control. As such, reported values from the most recent year (2022 at the time of writing) can be expected to underestimate regional withdrawals. Data below are discussed and displayed in millions of gallons used per day (mgd).
Regional Demands by Source
Water demand in the American Bottoms region is dominated by surface water demands. Surface water supplies in the region are often viewed as plentiful because of the Mississippi River's significant size.
Time series of reported groundwater and surface water withdrawals in the American Bottoms Water Supply Planning Region since 1980 through 2020.
Map of groundwater and surface water withdrawals throughout the American Bottoms WSPR in 2020 (as reported to IWIP).
The marked downturn in surface water withdrawals is primarily due to a lack of reports from one power generation facility after 2015. From 1980 to 2015, this facility reported using an average of ~250 mgd of surface water withdrawals.
The majority of the groundwater withdrawals reported in the region occur in the region's Mississippi Alluvial Aquifer. This sand and gravel aquifer was deposited by glacial advances and the meandering of the ancestral Mississippi River. The sand and gravel composition creates a highly productive and transmissive aquifer that has been used by local communities and municipalities.
A significant amount of groundwater is withdrawn near the boundary between Monroe and St. Clair counties as part of an Illinois Department of Transportation dewatering effort to prevent flooding along vital commercial interstates.
Water supplies withdrawn from surface waters have been nearly double the withdrawals of groundwater in 2019, 2020, and 2021 (figure below).
Reported water usage in the American Bottoms region for 2019 (left), 2020 (center), and 2021 (right) separated by the water source - whether groundwater or surface water withdrawals. Records are displayed in "millions of gallons used per day" (mgd).
Regional Demands by Usage Sector
In recent years, the primary use of water withdrawn in the region is for municipal supply. Nearly all of the surface water withdrawn reported in recent years is allocated for municipal supply, while nearly half of the groundwater pumped from the aquifer is used for municipal supply (figure below).
Reported groundwater (left column) and surface water demands (right column) in millions of gallons per day (mgd) for the American Bottoms region separated by year and usage sector. Each row of subplots represents a different year's reported data - i.e., 2019 is the uppermost two plots, 2020 is the middle plots, and 2021 is the lowest two plots in each column. Each bar plot presents the amount of water used for "municipal", "industrial", or "irrigation" purposes as reported to IWIP.
Municipal groundwater demands in the American Bottoms region are from Edwardsville, Glen Carbon, Wood River, East Alton, and Dupo, Illinois. In 2021, municipal demands were predominantly from Edwardsville who reported withdrawing about 65% of the regional groundwater withdrawn for municipal use, which corresponds to about 39% of all regional groundwater withdrawals.
Municipal surface water demands are primarily the result of Illinois American providing water to East St. Louis, Alton, and Granite City, Illinois, with East St. Louis being the primary recipient. For example, in 2021, East St. Louis received about 60% of the surface water withdrawn in the American Bottoms region, all of which was used for municipal purposes.
Funding Information
This story map is part of a series about Water Supply Planning throughout the state of Illinois. Water Supply Planning is an ongoing research effort conducted by the Illinois State Water Survey and is funded by the Illinois Department of Natural Resources Office of Water Resources.
