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  • Temporal changes in deep bedrock groundwater quality in northwestern Illinois


  • Deep bedrock aquifers in northeastern Illinois are an important source of drinking water, but there is evidence of temporal increases in concentrations of dissolved contents in the groundwater. Large groundwater withdrawals may be inducing groundwater movement from adjacent units or downdip areas containing high concentrations of dissolved solids. Archived data were used systematically to examine temporal trends in water-chemistry data for deep bedrock aquifers in northeastern Illinois. Most data suggest that concentrations of major ions and total dissolved solids (TDS) are not increasing in wells open to deep bedrock aquifers in most of northeastern Illinois. There are some locations where concentrations of some ions and TDS are increasing, including the major pumping centers at Joliet and Aurora, however. The increasing concentrations may be affected by aquifer geology. Increasing trends are more likely in wells open to deep Ordovician aquifers than in wells open only to deeper Cambrian aquifers or open to shallower Ordovician aquifers. There also appears to be some areal control on water-chemistry changes. Most of the positive trends occurred in the southern twothirds of the study area. Correlating withdrawal rates with water-chemistry data is problematic due to data limitations, but withdrawal rates do not appear to influence water chemistry of most wells for which data were available.

Originally Deposited as: 999999994455

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Language(s): EN-English

Volume or Year: 2005
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Date Created: 6 7 2005
Date Last Modified: 6 7 2005

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1. Temporal changes in deep bedrock groundwater quality in northwestern Illinois (20061003184752_ISWSCR2005-05.pdf).
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