•October 14, 2015•

Deep sandstone aquifers that feed water supplies to parts of northeastern Illinois are at risk of becoming partially or completely depleted in the next 35 years, a new study at the Illinois State Water Survey (ISWS) suggests.

Daniel Abrams, a groundwater flow modeler at the ISWS, University of Illinois, and colleagues conducted the largest measurement of deep sandstone groundwater levels in 34 years.  Water levels in 576 wells were measured in 33 counties between July 2014 and February 2015.

In northeastern Illinois, the sandstone aquifers are hundreds of feet deep, meaning that water pumped from the aquifer is not readily replenished by precipitation. As a result, water levels are hundreds of feet lower than when deep pumping began in the Chicago region in the 1800s.

“Most of the first wells constructed in northeastern Illinois were flowing,” Abrams said.

Currently, water levels are hundreds of feet below land surface, often at or near the top of the sandstone. This creates a risk of depletion, also known as desaturation, of the sandstone aquifers. Desaturation has potential negative outcomes, including the fact that small-capacity wells penetrating the upper portion of the sandstone may go dry.     Login or Subscribe to read the rest of this story.