Kane County Water Resources Investigations: Simulation of Groundwater Flow in Kane County and Northeastern Illinois

This report discusses an assessment of groundwater resources supplying water to Kane County, Illinois, a rapidly growing county on the west side of the greater Chicago metropolitan area. This study assimilates the available data into a set of computer models of groundwater flow in regional and local aquifers, quantifying the components of the hydrologic cycle and assessing the impact of historical and projected pumping. The modeling study is part of a comprehensive project assessing surface water, geology, and groundwater in Kane County. The water resources assessment project was motivated by a combination of factors and trends. The population of Kane County is projected to increase more than 70 percent from the 2000 population to over 718,000 by 2030. Although this population increase likely will be accompanied by greatly increased water demand, Lake Michigan, the source of water upon which the northeastern Illinois region has historically relied, may not be available due to legal constraints and the significant expense of conveying water from the lake to Kane County. These limitations have prompted planners and decision-makers to look to water resources within Kane County to meet projected demands. Studies conducted prior to the initiation of the present investigation in 2002 offered only a regional, qualitative understanding of the geology and hydrology, scattered sets of sporadic observations, and isolated studies of local issues. Although these legacy studies are inadequate for fostering detailed water-resources planning, they suggested the possibility of water shortages in Kane County by 2025 (Northeastern Illinois Planning Commission, 2002). In response to these factors, the Kane County Development Department commissioned the Illinois State Water Survey and Illinois State Geological Survey to assess groundwater and surface water resources to support county water-supply planning efforts. This assessment includes the present study, whose goal is to ascertain the current and future status of groundwater resources in Kane County, Illinois. To achieve this goal, this study develops and applies computer models of groundwater flow to clarify the relationships between aquifers and streams and to quantify the effects of current and future groundwater usage. The study assembles the data collected in the field, retrieved from archives and synthesized during 2002 to 2006, and assimilates them into computer models that simulate groundwater flow. This executive summary briefly describes the development, application, and results of computer modeling conducted for the study. The more extensive main report discusses the hydrologic characteristics of geological materials in the Kane County area and documents the data review and inference of parameters, the development and calibration of the groundwater models, and their detailed results. Readers should consult the main report for these details, as well as an overview of hydrogeologic concepts, the regional setting, and model development. Readers interested in basic concepts of hydrology may find the introduction by Alley et al. (1999) to be useful. Anderson and Woessner (2002) provide extensive guidance on the practice of developing groundwater flow models.