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  • A comparison of potentiometric surfaces for the Cambrian-Ordovician aquifers of northeastern Illinois, 1995 and 2000.


  • In response to expanding urban development, the use of Lake Michigan and other sources for public water supplies, and a growing interest in regional water resources development, this report provides a detailed discussion of groundwater withdrawals and water levels in northeastern Illinois. The water-level portion of this report covers a 15-county area from Lake Michigan to north-central Illinois and from the Wisconsin border south to Kankakee County. Particular emphasis, however, has been given to deep well pumpage in the eight counties of the Chicago region because of the significant shift in the late twentieth century from groundwater supplies of the deep bedrock aquifers to Lake Michigan and other sources. This report details the fall 2000 water-level measurement of wells reaching to the St.Peter and Ironton-Galesville sandstones (deep bedrock aquifers), provides a map illustrating the slope of groundwater levels, and compares the fall 2000 levels to the fall 1995 observations. The rapid decrease in groundwater pumpage from the deep bedrock aquifers during the 1980s initially resulted in a rapid recovery of groundwater levels. However, the rate of water-level change has slowed since the mid-1990s. The greatest recovery during the past five years occurred in Cook County. Groundwater levels in several wells were observed to have risen more than 50 feet since 1995. Where the deep bedrock aquifers of Cambrian-Ordovician age continue to be used, declines in groundwater levels were observed. Most notable declines were in southeastern Kane and northern Kendall Counties, southwestern Lake County, and southeastern McHenry County. Outside the Chicago region, water-level declines were observed in deep wells at Loves Park in Winnebago County and in the vicinity of DeKalb and Sycamore in DeKalb County.

Originally Deposited as: 999999994346

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Language(s): EN-English

Volume or Year: 2002
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Date Created: 9 24 2004
Date Last Modified: 5 12 2004

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1. A comparison of potentiometric surfaces for the Cambrian-Ordovician aquifers of northeastern Illinois, 1995 and 2000. (20061005193806_ISWSDCS2002-02.pdf).
Document Size:1685257 Software: Adobe Acrobat Version: 7.0