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QUADRANGLE: Monticello, 7.5' series

LOCATION: Lat 40 01' 51", long 88 35' 20", in NE1/4 SW1/4 sec.12, T.18 N., R.5 E., Piatt County, Hydrologic Unit 07130006, on right downstream side of highway bridge, 0.5 mile west of Monticello, and at mile 162.2.

ESTABLISHMENT: Chain gage was established Feb. 4, 1908, and discontinued Sept. 30, 1912; reestablished Oct. 31, 1912, and discontinued Dec. 31, 1912; reestablished June 13, 1914. Type- A wire-weight gage installed Mar 31, 1941, at site 0.2 mile downstream. Type-A wire-weight gage installed Sept. 30, 1964, at present site. Digital water-stage recorder operated by bubble gage installed Oct. 22, 1971. Digital recorder removed and replaced by a CR10 datalogger on Sept. 7, 1988. An additional pvc-tube stilling well was installed on the downstream side of the bridge Apr. 3, 1991. The bubble gage was removed on Aug. 3, 1993.

DRAINAGE AREA: 550 sq. mi.

GAGE: CR10 datalogger with phone modem operated by a stilling well and float located in a 5'4" x 5'4" Armco steel shelter. The stilling well is located on the center pier on the downstream side of the bridge. The outside base gage is a type-A wire-weight gage bolted to the downstream handrail of bridge. Correct check bar reading is 33.707 ft.

GAGE DATUM: Datum of gage is 625.89 ft. NGVD, datum of 1929.

HISTORY: Published as "near Monticello" during 1910-12.

CHANNEL AND CONTROL: Bed of stream is mud and fine gravel, with occasional sand. Considerable depth, even at low stages, in reach from highway to railroad (RR) bridge 100 yards downstream, becoming shallower downstream of the railroad bridge. Right bank is high from highway to railroad bridge, subject to little overflow. Left bank at the gage overflows at about a stage of 11.0 ft. Both banks are heavily wooded and can overflow downstream from the railroad bridge at about a stage of 11 ft. All water passes through the RR bridge which affects the control at high stages.

The low-water control is sand and gravel bars about 200 yards downstream of the gage and at the first bend in the river. This control is subject to scour and fill and the accumulation of debris. At times, beaver dams have been known to affect the control conditions. The channel and/or railroad bridge (100 yds downstream) is the control at medium and high stages.

DISCHARGE MEASUREMENTS: May be made by wading at low stages, usually about 100 to 150 yards below railroad bridge, in the reach between the first and second bends. Ice measurements are made at the wading section when feasible. High water is measured from the highway bridge, which is marked at 5 ft. intervals with initial point at the face of left abutment.

Sewage-treatment-plant effulent dischrges at the left bank about 300 ft downstream of the gage. This effluent is not included in the computation of discharge records. Therefore, the effluent must be measured and subtracted from streamflows that are measured downstream of the effluent outfall.

FLOODS: Oct. 4, 1926, 19,000 cfs (gage height, 18.50 ft.). Maximum gage height occurred April 13, 1994, at 19.06 ft. (discharge, 15,900 cfs.)

POINT OF ZERO FLOW: About 3.0 ft. (July 26, 1994)

WINTER FLOW: The control is not always frozen when ice cover occurs at gage, but ice effect can occur.

REGULATION AND DIVERSION: None known.