LOCATION.--Lat 40°49'30", long 92°53'33" referenced to North American Datum of 1927, in SE 1/4 NW 1/4 NE 1/4 sec.35, T.70 N., R.18 W., Appanoose County, IA, Hydrologic Unit 10280201, at control tower of Rathbun Dam, 1.8 mi north of Rathbun, 3.9 mi upstream from Walnut Creek, and 30.1 mi upstream from Iowa-Missouri state line. (map)

DRAINAGE AREA.--549 mi².

SURFACE-WATER RECORDS

PERIOD OF RECORD.--Reservoir storage (acre-ft) records from October 1969 to September 2000; stage-only records from October 2000 to current year.

GAGE.--Water-stage recorder. Datum of gage is 0.00 ft above National Geodetic Vertical Datum of 1929.

REMARKS.--Reservoir is formed by earthfill dam completed in 1969. Storage began in November 1969. Release is controlled by two hydraulically controlled slide gates, 6 ft wide and 12 ft high, into forechamber of an 11-ft diameter horseshoe conduit through the dam. No dead storage. Maximum design discharge through gates is 5,000 ft³/s. Uncontrolled notch spillway is concrete overflow section, 500 ft in length, located about 3,000 ft west of the right abutment of the dam, and provides emergency discharge into the adjacent drainage area of Little Walnut Creek. Uncontrolled notch spillway is at elevation 926 ft, contents 545,621 acre-ft, surface area 20,974 acres. Conservation pool level is at elevation 904 ft, contents 199,830 acre-ft, surface area 10,989 acres. Reservoir is used for flood control, low-flow augumentation, conservation and recreation.

Advanced Hydrologic Prediction Service

U.S. Army Corps of Engineers - Kansas City District