LOCATION.-- Lat 41°42'36", long 87°58'33" (NAD of 1927), Hydrologic Unit 07120004, at Argonne National Laboratory. Owner: Argonne National Laboratory.

AQUIFER.-- Niagara Dolomite of Middle Silurian Age.

WELL CHARACTERISTICS.-- Drilled unused artesian well, diameter 10 in., depth 199 ft., cased to 86 ft.

PERIOD OF RECORD.--

GROUND-WATER LEVELS: November 1948 to September 1990.

REVISED RECORDS.-- WDR IL-79-2: 1978(H).

INSTRUMENTATION.-- Digital water-level recorder--60 minute punch.

DATUM.-- Land-surface datum is 705 ft above NGVD of 1929. Measuring point: Top of casing, 2.40 ft above land-surface datum.

REMARKS.-- Ground water-levels affected by pumping of nearby wells.

EXTREMES FOR PERIOD OF RECORD.--

GROUND-WATER LEVELS: Higest water level, 57.79 ft below land-surface datum, May 8, 1950; lowest, 97.55 ft below land-surface datum, Aug. 18, 1989.