By 2030, the Cambrian-Ordovician aquifer system that supplies Will, Kendall, Kane, and McHenry Counties is projected to not be able to meet the monthly water demand in parts of the region. That’s according to a 2015 report by the groundwater science team at the Illinois State Water Survey (ISWS) and updated modeling by the ISWS conducted in late 2018 for the city of Joliet.
Joliet, located in Will County, is Illinois' third-largest community, and it rests on top of a major “cone of depression” for the aquifers, with groundwater levels so dangerously low that some wells in the area may not be usable by 2030. Consequently, Joliet, and other communities and industries in the region, need to switch to an alternative water source.
Taking an innovative approach
Facing an imminent water shortage and drilling deeper into its aquifers to meet demands, planning committees and legislators from Joliet and surrounding communities are calling on the ISWS to meticulously assess and monitor the aquifers’ supply, the region’s water demand, and carefully craft a path to transition to alternative water solutions.
“Water is the lifeblood of any community, and we know we cannot take it for granted, so for Will County we know we are facing a very real issue and needed the help and expertise of the ISWS,” said director of water resources at the Metropolitan Planning Council, Danielle Gallet.
The ISWS has built groundwater models that simulate the region’s water usage based on monthly - and in some cases, daily - data from Will, Kendall, Kane, and McHenry counties. This has resulted in the most accurate modeling of the aquifers to date and led the team to win the National Ground Water Association Outstanding Groundwater Supply Project Award for 2019.
“The key is the data,” said Daniel Abrams, principal investigator on the project. “Thanks to the level of participation from communities and industries, we now have a data-rich area, which
allows us to model these in near real time, which is truly unique.”
According to Abrams, the level of detail in both the data and the model was not available 10-20 years ago, but once the groundwater team’s model was updated to match the entire historic data record, they started to discover more factors that are at play - like changes in well construction over time, the effects of drilling to various depths among multiple aquifers, and the impact of dewatering different geologic formations.
Putting a new approach into action
A city campaign dubbed “Rethink Water Joliet” has been examining viable water solutions for Joliet based on the monthly simulations provided by the ISWS.
“We knew we had to get ahead of this because water shortages could be absolutely devastating for the region, so we commissioned the ISWS to start a multi-phase assessment of our options moving forward,” said Allison Swisher, public utilities director for Joliet.
Conceptual image showing 2014 head in relation to the sandstone aquifers in northeastern Illinois
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The first phase evaluated 14 alternative water sources for water quality and sufficient quantity for the city’s and region’s current and future needs. Out of the 14 proposed alternate sources, the Illinois River, Kankakee River, Lake Michigan by way of the City of Chicago, DuPage Water Commission, and a new Indiana intake are being evaluated further to assess reliability, regulatory considerations, governance, jurisdiction, control, risk, and the anticipated cost of water.
According to Swisher, the results from the second phase of the study will be released in November 2019. The Joliet City Council is expected to make a final decision on where the city will get its water by the end of the year.
The water shortage is a multifaceted issue
The Cambrian-Ordovician aquifer system includes three major aquifers: the St. Peter sandstone, Ironton-Galesville sandstone, and Mt. Simon sandstone. Multiple factors have led to the rapidly declining groundwater supply in the sandstone aquifers.
First, the aquifers are hundreds of feet below the land surface, covered by material that impedes the vertical movement of water, preventing rainfall from replacing water withdrawn from the aquifers.
Second, wells constructed before the 1980s connected multiple aquifers that led to changes in groundwater circulation.
“The wells open to multiple aquifers provide artificial conduits that short circuit natural recharge processes,” said Walt Kelly, head of the groundwater team at the ISWS. “We’ve allowed water to flow between the aquifers, which increases the complexity of the modeling.”
In contrast to the historical record, newly constructed wells in the region have been open only to the Ironton Galesville aquifer, limiting the available water in areas of new growth and accelerating declines.
Lastly, municipal and industrial developments are expanding closer to the Sandwich fault zone. The presence of the fault zone disrupts the sandstone layers, partially offsetting the aquifers and acting as a barrier impeding the movement of water and exacerbating groundwater declines near the fault. This results in pumps needing to be dropped deeper and deeper in the wells in order to get sufficient water. With demands projected to increase in the coming decades, the future availability of water from the sandstone is in jeopardy.
For more information, videos, and interactive maps about water supply planning throughout Illinois, please visit isws.illinois.edu.
