USGS Water-Year Summary 2024
421321088341101 MARS-09-01
Sand and gravel aquifers (glaciated regions)
Quaternary System
LOCATION - Lat 42°13'21.06", long 88°34'11.17" referenced to North American Datum of 1983, in SE 1/4 NE 1/4 NE 1/4 sec.07, T.43 N., R.6 E., McHenry County, IL, Hydrologic Unit 07090006, 41 feet west of driveway to McHenry County Coral Woods Maintenance Facility, 94 feet northeast of barn, 127 feet southwest of Route 20 (South Grant Highway), 0.2 miles northwest of Tributary to Kishwaukee River. 0.5 miles northwest of the town of Coral, and 1.6 miles southwest of the town of Union. Owner: Illinois State Geological Survey.
REVISIONS HISTORY - Revisions: Land-surface datum was updated to 924.78 ft NAVD88 on May 30, 2023, as determined by a GNSS Level II survey. Land-surface datum was previously published as 928 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 190.3 ft. Upper casing diameter undefined; top of first opening 185 ft, bottom of last opening 190 ft. Well-casing includes 2-inch schedule 40 PVC pipe, 5.5 in. diameter borehole sealed with benseal grout, observation well.
DATUM - Land-surface datum is 924.78 ft above North American Vertical Datum of 1988. Measuring point: Black mark on top east side of PVC well casing, 3.38 ft above land-surface datum, Jul. 29, 2009 to Apr. 20, 2022; Black mark on top east side of PVC well casing, 931.38 ft above land-surface datum, Jul. 29, 2009 to present; Black mark on top east side of PVC well casing, 3.36 ft above land-surface datum, Apr. 20, 2022 to present.
PERIOD OF RECORD -
GROUND-WATER LEVELS: September 2009 to current. Prior to September 2009,
observation well readings available from the Illinois State Geological Survey.
GROUND-WATER QUALITY:
CHEMICAL: Water year 2011.
GAGE - Water level recorder and satellite telemeter.
EXTREMES FOR PERIOD OF RECORD - Highest water level, 67.96 ft below land-surface datum, May 30, 2019; lowest, 79.93 ft below land-surface datum, October 15, 2012.