Illinois could require 20 to 50 percent more water in coming decades to meet the projected needs of a growing population and economy. As a state, we need to know: How much water will be available and how much will be needed? What are the options for finding additional supply and reducing demand? What will the impacts and costs be?

PRI conducts research, collects data, and provides analysis about groundwater issues like water supply planning and water safety. PRI is Illinois’ primary repository of groundwater records and data, including water well construction reports, hydrologic reports, groundwater level and quality data, and aquifer data and mapping. Services provided include groundwater flow modeling and data analysis to support water supply planning, risk assessment, and regional water quality studies.

PRI scientists developed an interactive map of the water sources of every Illinois community and a range of other interactive water supply maps. Sources of water throughout the state include Lake Michigan; inland surface waters, such as rivers and reservoirs; groundwater, such as from an aquifer; or a combination of sources. Communities either self-supply their water or buy water from other communities or public water distributors. The web of water purchases is quite complex, particularly for Lake Michigan users. Sometimes water is bought and resold and can pass through many facilities before reaching its final destination.

Water Supply Planning

PRI leads regional water supply planning activities across Illinois, helping communities understand their water availability and needs and guiding them to sustainable water resource decisions. Since 2006, the Illinois Department of Natural Resources has tasked PRI with leading regional water supply planning activities for Illinois’ 11 planning regions. To date, PRI has conducted this work in the East Central Illinois Basin Region, Kankakee Subregion, Kaskaskia River Basin Region, Middle Illinois Region, Northeastern Illinois Region, Rock River Region, and American Bottoms Region.

Predictive modeling

PRI has a long history of groundwater modeling and even pioneered early modeling technologies. Modern water supply models have become much more adaptable, providing answers for a localized area to a specific question using inputs on climate, local hydrology, aquifer specifications, and many other factors.

Groundwater modeling is vital for protecting local and regional water supplies by predicting potential supply and contamination issues. These models can help communities adjust course from unsustainable practices before it’s too late, ensuring future generations have clean, available water. In northeastern Illinois, PRI analysis determined that aquifer water levels would be unable to meet demand by 2030 in some areas, affecting Chicago’s southern suburbs in Will, Kane, Kendall, and McHenry counties. As a result, some communities in this region have pursued new sources of water.

Advanced mapping

PRI uses helicopter-based time-domain electromagnetics (HTEM) to create detailed 3D maps of the Earth’s subsurface, revolutionizing our understanding of Illinois’ groundwater and providing information to improve critical water resource management.

Around 3.8 million Illinois residents use groundwater as their primary source of drinking water. However, there are limitations to the traditional drilling methods of studying sedimentary layers and the groundwater they hold. Incorporating HTEM data creates a much more intricate picture of important groundwater sources called aquifers. The Mahomet aquifer is a major aquifer providing water to more than half a million people in central Illinois.

Models using HTEM data empower data-backed decisions that protect public health, assure adequate drinking water for future generations, prioritize actions that remediate threats or reduce contamination risk, promote and guide equitable planning for sustainable development and economic growth, address emerging needs caused by climate change, and strengthen local emergency response. In emergencies, like chemical spills or train derailments, a detailed map of the subsurface will help determine whether groundwater has been contaminated and how to remediate it.

HTEM data reveals information about geologic materials hundreds of feet underground, similar to how an MRI creates images of the inside of a body. A large, non-metallic frame is lifted by a helicopter and suspended below it as it flies precisely across a geographic area on regularly spaced flight lines. A coil wrapped around the frame transmits an electric current, creating an electromagnetic field in the ground. Different geologic materials carry electromagnetic energy differently, revealing the thickness, shape, and distribution of subsurface materials. 

HTEM technology is a safe, non-destructive, and non-invasive method of gathering data on the aquifers people rely on for safe drinking water, agriculture, and industry.

Water Safety

In the late 1800s, scientists at the Illinois State Water Survey — today part of PRI — traced the spread of waterborne diseases like typhoid. Using scientific investigation to find the cause of the deadly disease, they tested more than 21,000 water samples from 900 towns in all Illinois counties. This water monitoring initiative marked the beginning of the scientific study of water pollution in Illinois.

Contaminants

PRI investigates environmental contaminants, ways to prevent them from entering environments, and ways to protect the water quality and safety of Illinois residents. Learn more about PRI’s research into contaminants, including those that threaten water safety, like lead.

Water safety education and training

PRI leads nationwide training and outreach programs to help private well owners and small, rural water operators ensure their drinking water is safe.

More than 15 million private wells provide the primary source of drinking water to 15% of the U.S. population — including approximately 2 million Illinoisans — but a majority of well owners don’t know how to care for their wells, determine if their water is safe to drink, or protect groundwater from contamination. 

PRI’s Private Well Class provides online and in-person training to well owners, as well as real estate, environmental health, cooperative extension, and water well professionals. The program reaches all 50 states, tribal lands, and U.S. territories, has educated more than 15,000 people through online courses and webinars, and also offers Spanish-language materials. It has been supported since 2013 by the Rural Community Assistance Partnership with funding from the U.S. Environmental Protection Agency. 

WaterOperator.org, also supported by RCAP since 2010, aggregates the best resources on the web for small water system operators. This free, user-friendly hub indexes more than 11,000 training events annually and more than 17,000 free resources. 

Protecting Jo Daviess County’s water supply

Jo Daviess County is highly susceptible to water contamination due to its karst geology marked by sinkholes, crevices, and caves. 

PRI scientists, the League of Women Voters of Jo Daviess County, and county residents worked together to establish a countywide group of farmers to advise on water resource management issues. That collaborative effort continued for years, resulting in studies that helped residents and officials understand the water quality issues in the county and protect their water supply. 

A compilation of this PRI data is now available to the public through the Karst Feature Database hosted by the U.S. Fish and Wildlife Service. The map has eight layers, two of which are sinkhole locations and bedrock crevices. The database has broad applications, such as for spill containment, but the primary goal is to raise the awareness of Jo Daviess County residents about the hydrogeology of the area so they can make better, more thoughtful land use decisions.