Water Supply Planning for Illinois
The availability and sustainability of an adequate and dependable water supply are essential for a society's public, environmental, and economic health. This important understanding led to the initiation, under direction of Executive Order 2006-01 in July 2006, of a three-year pilot program for comprehensive regional water -supply planning and management. Two areas were selected for pilot planning: an 11-county region in northeastern Illinois and a 15-county region extending across east-central Illinois. The State Scientific Surveys (the State Water and Geological Surveys) of the Institute of Natural Resource Sustainability were responsible for providing technical support to the two regions as well as analyzing the impact of future demand scenarios on available water resources. A Final Report is in production while maintenance of data-gathering and modeling activities continue. Presentations and more information on the project and the regional stakeholder committees can be found at: http://www.isws.illinois.edu/wsp/
Scenarios for water demand to the year 2050 were developed for each region. Because such demand predictions are uncertain, especially with a time-horizon of 40+ years, various assumptions were used to present a range of possible, plausible future water needs. Using population and economic growth projections and regional historical water withdrawal data collected and maintained by the Water Survey's Illinois Water Inventory Program (IWIP), three basic water demand scenarios were generated: a business-as-usual or baseline scenario, a low-resource-intensive scenario invoking conservation trends, and a more resource-intensive scenario assuming an increased per capita demand. County-level information on possible water needs for five water use sectors was prepared: public supply, self-supplied industrial/commercial, power, irrigation/agriculture, and self-supplied domestic. In addition, specific point-withdrawal (wells and surface intakes) data for each demand scenario were determined. This was especially important to the State Water Survey for incorporating into model simulations.
Findings to Date: Modeling results indicate that for east-central Illinois, surface reservoir capacities are insufficient to meet increasing demands under drought conditions, and potentially limiting drawdown impacts on the Mahomet aquifer will be experienced in the Champaign County area. For northeast Illinois, Lake Michigan will continue to be the major water source; however, it cannot be relied upon to solve supply shortfalls much beyond its current service area. Model results suggest the deep bedrock aquifers beneath northeast Illinois are being pumped at unsustainable rates. Shifting groundwater withdrawals to shallow aquifers is important but not without problems, as increasing shallow groundwater withdrawals will impact wetlands and streamflow. Analysis suggests the Fox River can provide additional water to meet future demand. Water conservation is likely to be another key factor to reducing the need for additional water.
Selected Related Publications
Reports on water demand for each region were prepared by Dr. Ben Dziegielewski at SIU-Carbondale and by Wittman Hydro Planning Associates. Further, final reports have been prepared by each regional water supply planning stakeholder committee.
Reports for Northeastern Illinois can be found here: http://www.cmap.illinois.gov/watersupply/default.aspx
Reports for East-Central Illinois can be found here: http://www.rwspc.org/commproducts.htm