Reversal of declining ground-water levels in the Chicago area

Abundant water resources have been an important part of the economic development of the Chicago area for more than a century. The city of Chicago, Ill., and other lakefront towns have used Lake Michigan as a water supply. Where water from Lake Michigan was not available or a need for supplemental water supplies was present, deep wells (generally greater than 700 feet) provided a clean, reliable, and abundant water supply from the Cambrian-Ordovician aquifer. Public water suppliers withdraw the most ground water in the eight-county Chicago area (Cook, Du Page, Grundy, Kane, Kendall, Lake, McHenry, and Will Counties). This report describes a reversal in the trend of declining ground-water levels in the Cambrian-Ordovician aquifer in the Chicago area as public water suppliers have converted from the withdrawal of ground water from wells to the withdrawal of surface water from Lake Michigan.