Northeastern Illinois Water Supply Planning Investigations: Opportunities and Challenges of Meeting Water Demand in Northeastern Illinois--Full Report

The availability and sustainability of an adequate and dependable water supply is essential for public, environmental, and economic health. This understanding led to the initiation, under the direction of Executive Order 2006-01, of a three-year program for comprehensive regional water supply planning and management in Illinois. The Illinois Department of Natural Resources' Office of Water Resources (IDNR-OWR), in coordination with the Illinois State Water Survey (ISWS), selected two regions having a high potential for water conflict—east-central Illinois and northeastern Illinois—for pilot planning under the framework of the Order. This report summarizes technical studies in support of water supply planning in the northeastern Illinois region, which includes Boone, Cook, DeKalb, DuPage, Grundy, Kane, Kankakee, Kendall, Lake, McHenry, and Will Counties. These studies highlight the opportunities and challenges of meeting water demand in the region. The Chicago Metropolitan Agency for Planning (CMAP) guided formation of a 35-member grassroots water supply planning group for northeastern Illinois, the Northeastern Illinois Regional Water Supply Planning Group (RWSPG). The RWSPG was charged with developing water supply planning and management recommendations for the region. The Illinois State Water Survey (ISWS) and the Illinois State Geological Survey (ISGS), both within the University of Illinois' Prairie Research Institute, along with the Illinois Department of Natural Resources' Office of Water Resources (IDNROWR), were responsible for providing technical support to the RWSPG. A water supply study program, developed by IDNR-OWR and the State Surveys, called for estimation of water withdrawals to 2050 and assessment of the impact on the region's water resources of these withdrawals. This report describes estimated impacts based on scenarios of future water withdrawals developed by Southern Illinois University investigators. The authors discuss impacts to three principal sources of water available to the region: the deep bedrock aquifers (called the deep aquifers) underlying all of the region; sand and gravel and shallow bedrock aquifers (called the shallow aquifers) underlying only the Fox River watershed; and the inland surface waters of the Fox River. The authors also assess the ability of Lake Michigan to meet public water supply demand. A surface water accounting tool, a watershed model, and a groundwater flow model were developed to estimate the impacts of future demands on the Fox River and aquifers within the region. Time and budget limitations did not permit the authors to evaluate shallow aquifers outside of the Fox River watershed nor other inland surface waters such as the Kankakee River. Figure ES-1 illustrates the planning region.