Population growth may be an economic boon for communities and counties, but the subsequent increased water demand could threaten the amount and quality of public water supplies available within the next few decades, according to Scott Meyer, hydrogeologist at the Illinois State Water Survey, a division of the Institute of Natural Resource Sustainability at the University of Illinois.

In fact, the state of Illinois could require up to 50 percent more water within 40 years.

"Concerned groups at the community and county level are beginning to realize that water supply planning is a priority issue," Meyer said. "It is important to know which local water resources will be affected by rising demand, potential drought, and climate change and the degree to which these resources will be affected."

Significant groundwater pumping causes water levels inside wells to decline, leading to higher costs and possible well failures, less groundwater flowing to local streams, and lower water levels in lakes and wetlands. Pumping can even cause poor quality groundwater, Meyer said.

Researchers at the Illinois State Water Survey (ISWS) assist water supply planners to assess current water supply conditions and evaluate the availability, quality, and use of local surface and groundwater resources.

One tool often used is the groundwater flow model— sets of interrelated mathematical equations that represent water flow in aquifers and streams. Computer programs are used to solve the equations, thereby determining the effects of current and future groundwater usage and stressors, such as drought.

"The models provide a rational basis for developing policy and management strategies pertaining to water-resources development in the area," Meyer said.

Since the population in Kane County on the west side of the Chicago area is expected to surge 70 percent by 2030, county groups have taken progressive steps to predict water supply changes to ultimately avoid water shortages in the future.

The Kane County Development Department commissioned the ISWS (and sister agency Illinois State Geological Survey) to assess water resources in Northeast Illinois and forecast potential changes in water supply and quality to the year 2050.

After developing regional- and local-scale groundwater flow models for Kane County, Meyer and his colleagues at ISWS predicted that groundwater pumping in the county may increase from 37 million gallons per day (mgd) in 2000 to as much as 71 mgd by 2050 to meet increased demand.

Model simulations also showed:

• Groundwater withdrawals from deep wells will potentially cause water supply interruptions and increasing concentrations of radium, barium, arsenic, and salinity in the water supply. These problems will be greatest in the Aurora area.
• In shallow wells, the researchers identified two large areas of significant drawdown, or declines in water levels. The largest area included parts of northeastern Kane County and Southeastern McHenry County, and the second area developed in response to pumping by the City of West Chicago. A third area will likely develop around public-supply wells operated at Batavia and Geneva.
• Water in local streams may decline, potentially harming fish populations and plants. During periods of low precipitation, Mill Creek, for example, may dry up completely by 2050.

Study results are available on the ISWS Web site at http://www.isws.illinois.edu/docs/pubs/ISWSCR2009-07/

"Although the data and projections are specific to Kane County, the studies can be used as a framework for water supply planning initiatives in other Illinois counties," Meyer said.

Communities or counties interested in assessing their water resources will want to start by determining present and future water needs and by gathering data on existing water sources, including water levels in wells, stream levels, and interactions between groundwater and surface water.

For more information on water supply planning, contact the ISWS Center for Groundwater Science, (217) 333-4300.