USGS Water-Year Summary 2024
421122088222701 16-GRF-I
Sand and gravel aquifers (glaciated regions)
Quaternary System
LOCATION - Lat 42°11'22", long 88°22'27" referenced to North American Datum of 1983, in NE 1/4 NE 1/4 SE 1/4 sec.23, T.43 N., R.7 E., McHenry County, IL, Hydrologic Unit 07120006, about 10 feet from southeast corner of parking lot in Exner Marsh Nature Preserve, 0.2 miles north of Exner Wetland, 2.3 miles northwest of Lake in the Hills, and 5.7 miles west of Fox River. Owner: McHenry County.
REVISIONS HISTORY - Revisions: Land-surface datum was updated to 879.46 ft NAVD88 on May 30, 2023, as determined by a GNSS Level II survey. Land-surface datum was previously published as 879.51 ft NAVD88 from LiDAR (furnished). Discrete water-level measurements prior to May 30, 2023, are referenced to the original datum.
GROUNDWATER RECORDS
WELL CHARACTERISTICS - Depth 99 ft. Upper casing diameter 2 in; top of first opening 94 ft, bottom of last opening 98.5 ft. Well-casing includes schedule 40 PVC pipe, 8 in. diameter borehole with bentonite seal, observation well.
DATUM - Land-surface datum is 879.46 ft above North American Vertical Datum of 1988. Measuring point: Top of PVC casing; High point marked, 2.47 ft above land-surface datum, Oct. 14, 2008 to present; Top of PVC casing; High point marked, 881.98 ft above land-surface datum, Oct. 14, 2008 to present.
PERIOD OF RECORD -
GROUND-WATER LEVELS: February 2009 to current.
GROUND-WATER QUALITY:
CHEMICAL: Water year 2011.
GAGE - Water level recorder and satellite telemeter.
EXTREMES FOR PERIOD OF RECORD - Highest water level, 8.85 ft below land-surface datum, July 25, 2017; lowest, 26.74 ft. below land-surface datum, Jun 13, 2021.