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STATION NUMBER: 05582000 QUADRANGLE: Mason City, 7 1/2' series LOCATION: Lat 40 08'01", Long 89 44'08", in NE1/4NE1/4 sec.2, T.19 N., R.6 W. Menard County, Hydrologic Unit 07130009, on left downstream side of bridge on State Highway 29, 3.3 miles downstream from Pike Creek, 3.5 miles north of Greenview, and at mile 4.9. ESTABLISHMENT: Type-A wire-weight gage (WWG) installed Oct. 1, 1941. Prior to Aug. 20, 1960, the gage was located on the old highway bridge at same site and datum. Digital water-stage recorder (ADR) and manometer installed Nov. 3, 1972. Installed a crest-stage gage on Sept. 6, 1978. A data collection platform (DCP) was installed on Dec. 1985 by Rock Island Corps. On Feb. 24, 1999 the ADR and manometer were replaced by a pressure sensor operating the DCP. DRAINAGE AREA: 1,804 sq. mi. GAGE: Sutron Accubar (Model-6) pressure sensor operating a U.S. Army Corps of Engineers Vitel DCP in a 5'4" x 5'4" Armco steel shelter. Base gage is a Type-A wire-weight gage (WWG) mounted on the downstream handrail of the bridge. A crest-stage gage (CSG) is located on the downstream side of the bridge near the WWG. Power to the gage is supplemented by a solar panel. The orifice is mounted on 2’’ steel pipe bolted to large concrete riprap 30’ downstream of the bridge at the left bank. The orifice is spliced at the top of the bank to a 600 ft. line trenched from the gage house. The deep scour hole under the orifice is subject to sand fill which can occasionally bury the orifice. GAGE DATUM: Datum of gage is 479.00 ft. above NGVD, datum of 1929. On Oct. 1941, Barron and Hull ran levels to the check bar from R.M. #1, a mark identical to mark described by letter from Mr. L.P. Murphy, U.S. Corps of Engineers, Peoria, IL (dated Nov. 12, 1942) as: "USGS bench mark, T. 19 N., R.6W., near north corner of sections 1 and 2, top of east end of south pier of steel highway bridge, State Route over Salt Creek, chiseled square...elevation 499.75 ft above NGVD, datum of 1929." On basis of two independent runs, which differed by 0.001 ft, check bar found to be higher than starting BM by 5.21 ft. CHANNEL AND CONTROL: Channel is straight about 500 ft upstream and downstream of the gage, but passes under the highway bridge at an angle. Both banks overflow about 13 ft into wooded and partially cultivated flood plains bordered by flood-control levees. Low stages are controlled by unstable sandbars 200-600 ft. downstream of the gage. The channel is the control for stages up to about 13 ft. Above 13 ft., the wooded and partially cultivated flood plains and levees become the control. DISCHARGE MEASUREMENTS: Low stages may be measured by wading 300 ft above the gage, or for higher stages, from the bridge at the gage. The wading section can be accessed by following the field road at the upstream left around to the sand and gravel beach located on both sides of the river 300 ft. upstream of the gage (see attachment). Downstream handrail is marked in five-foot intervals, with initial point at left abutment. River flows at an angle to the bridge with reverse flow and scour below piers. Measurements from the upstream handrail can be made if no debris is present. This will eliminate reverse flow and turbulent water. Ice measurements can be made at wading section. FLOODS: May 19, 1943, 41,200 cfs (gage height, 20.50 ft). Flood in July 1929 reached a stage of 20.3 ft, gage datum (from floodmark at left levee and roadway). POINT OF ZERO FLOW: About —1.2 ft. on Aug. 12, 1997 WINTER FLOW: Ice cover during cold weather. Floating ice often prevents measuring during extreme cold periods. REGULATION AND DIVERSION: Low flows may be affected by effluent from the City of Lincoln sewage-treatment plant. Personnel to contact about a specific subject are listed on the staff page. The URL of this page is <il.water.usgs.gov/proj/lirb/bst/site_descrip/greenview.html> Please send comments about this page to: <djfazio@usgs.gov>. This page was last updated on October 12, 1999. |
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