LOCATION.-- Lat 42°28'03", long 87°47'53" (NAD of 1927), in SW1/4NE1/4NW1/4 sec. 14, T.46 N., R.12 E., Hydrologic Unit 04040002, at Illinois Beach State Park, northern unit. Owner: U.S. Geological Survey.

AQUIFER.-- Elmhurst Sandstone member of the Eau Claire Formation and the upper Mount Simon Sandstone of Cambrian age.

WELL CHARACTERISTICS.-- One of three piezometers in 10-in. borehole, diameter 1.25 in., depth 1,684 ft, cased to 1,666 ft, 2-in. screen, drilled observation artesian well.

PERIOD OF RECORD.--

GROUND-WATER LEVELS: November 1988 to September 1997, December 1998 to current year (fragmentary). Miscellaneous water-level measurements from December 1981 to November 1988 are available in files of the U.S. Geological Survey.

INSTRUMENTATION.-- Manual steel-tape measurement made every 2 months.

DATUM.-- Land-surface datum is 586 ft above NGVD of 1929. Measuring point: Top coupling on 1.25-in. plastic pipe, 2.67 ft above land-surface datum.

REMARKS.-- Ground-water levels affected by regional pumping.

EXTREMES FOR PERIOD OF RECORD.--

GROUND-WATER LEVELS: Highest water level, 199.57 ft below land-surface datum, Oct. 23, 2000; lowest, 232.7 ft below land-surface datum, Oct. 18, Nov. 12, 18, 19, 28, 29, 1989.