QUADRANGLE: Hardin, 7 1/2' series
LOCATION: Lat 39 09'37", long 90 36'55", in NW1/4NW1/4 sec. 26, T.10 S., R.2 W, Calhoun County, Hydrologic Unit 07130011, on right bank at foot of downstream side of State Highways 16 and 100 bridge at north edge of Hardin, 1.6 mi. downstream from Macoupin Creek and at river mile 21.5.
ESTABLISHMENT AND HISTORY: Staff gage installed and operated by U. S. Army Corps of Engineers, St. Louis District, since February 1932. Wire-weight gage, crest stage gage, Servo manometer and Analog Digital Recorder (ADR) put into operation Sept. 18, 1986 by D. L. Olson and D. J. Sullivan. Handar Data Collection Platform (DCP) installed by the U. S. Army Corps of Engineers St. Louis District. ADR removed Mar. 16, 1994. The manometer was removed on June 4, 1997 by Mike Barfield of the St. Louis Corps and Joe Norris of the U.S.G.S., and replaced with a PS-2 pressure sensor.
July 1973 to September 1977, a two-parameter water quality monitor was operated at site about 0.25 mi. downstream. Additional chemical data collected from 1959-1977 and published in Water-Resources Investigations 78-23 and 79-24 as site D 01. Stage records since February 1932 available in files of U. S. Army Corps of Engineers, St. Louis District.
DRAINAGE AREA: 28,690 sq. mi.
GAGE: Handar Data Collection Platform (DCP) operated by PS-2 pressure sensor installed in 5'4" x 5'4" Armco metal shelter. PS-2 is set up so to emulate an encoder. A recording rain gage is mounted on the roof. The outside base gage is a Type-A wire-weight gage attached to the downstream handrail of the control tower walkway, about 75 ft streamward of the gage. A 20 foot long, 2 in galvanized steel pipe crest-stage gage (CSG) is mounted on the landward side of the right pier. Orifice is located about 25 ft downstream from and in line with right pier. DCP equipment installed by U. S. Army Corps of Engineers, St. Louis District and operated by USGS. Auxiliary power is supplemented by a solar panel.
GAGE DATUM: Datum of gage is 400.00 ft above NGVD of 1929. Levels run by Stahl and Sullivan from USAE GBM 2 (elevation 430.829 ft).
CHANNEL AND CONTROL: The streambed is composed of sand and silt. The low-flow channel (navigation channel) is about 900 ft wide and averages about 18 ft deep. Channel is straight for 1 mi. above and 1.5 mi. below the gage. This channel is periodically dredged and frequent barge traffic keeps the channel free from debris. The channel is the control for all stages with backwater effects from the Mississippi River 21.5 miles downstream.
DISCHARGE MEASUREMENTS: Acoustic Doppler Current Profiler (ADCP) measurements can be made by boat 200 ft downstream of the bridge.
FLOODS: 442.40 ft (42.40 ft gage datum), from high water mark, Aug. 3, 1993, from backwater caused by flooding on the Mississippi River. During the flood of 1973, reached a maximum stage of 438.2 ft (38.2 ft gage datum), April 29, 1973.
POINT OF ZERO FLOW: Not applicable.
WINTER FLOW: Ice cover can be a factor in most winters.
REGULATION AND DIVERSION: Stages are affected by operation of La Grange lock and dam 59.5 miles upstream, on the Illinois River and backwater from the Mississippi River 21.5 miles downstream.
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This page was last updated on November 15, 1999.