Authorization: Flood Control Act approved July 3, 1958, (Public Law 85-500) HD 170, 85th Congress. 1st Session and the Flood Control Act approved October 23, 1962. SD 137, 87th Congress 2nd Session. Modified in Section 102(v) of WRDA 1992 (106 Stat 1187), Section 338 of WRDA 1996 (110 Stat. 1808) and further modified to require seasonal adjustments to the Top of Conservation Pool in WRDA 1999.
Location: On the Mountain Fork River, a tributary of Little River, at river mile 20.3, approximately 9 miles north-northeast of Broken Bow in McCurtain County, Oklahoma.
Purpose: Flood control, hydroelectric power, water supply, recreation, and fish and wildlife.
History of Construction: Construction began in October 1961. Impoundment began in October 1968 and the conservation pool was filled in April 1970. The first power unit was put on line in January 1970 and the second unit in June 1970.
Type of Structure: The dam is a rolled, earth-filled structure about 2,750 feet long, rising 225 feet above the streambed. The dike has a maximum height of 55', a design crest elevation of 645.09, and a length of 897' (STA. 10+00 to 18+97). The total length of the dam, dike and spillway is 4,026 feet.
Spillway & Outlet Works: The controlled spillway is a concrete ogee weir located in a saddle about 1.25 miles northwest of the right abutment of the dam. Total length of the structure is 376 feet, with a clear opening of 320 feet controlled by eight 40-by-40-foot tainter gates. Design capacity of the spillway is 443,000 cubic feet per second (cfs) at full pool. Seven 8-foot-wide piers support a roadway bridge across the spillway. Operating channel capacity below the dam is 8,000 cfs. A 17-foot-diameter diversion tunnel and a 24-inch corrugated metal pipe through the left abutment act as a low-level outlet facility to discharge water below elevation 599.0. This low-level outlet is operated by four 5- by 7-foot hydraulic slide gates placed two in tandem in each of two openings. The two upstream gates will normally be reserved for emergency use. The 24-inch pipe is adjacent to the 17-foot tunnel and both discharge into the old river channel. The diversion tunnel and gates have structural issues. They should only be used in emergencies after consultation with District dam safety personnel. It is also believed that high discharges from the tunnel pose the risk of embankment erosion due to the lack of an adequate stilling basin. A 4- by 4-foot low flow sluice extends through the spillway weir.
Hydrologic Data: A flood of record occurred in December of 2015. The maximum outflow was measured as 41,443 cfs and the peak inflow was measured as 144,095 cfs on December 28th 2015. The flood of record, as recorded at the Eagletown gage, occurred in 1945, with a volume of 1,047,700 acre-feet, which is equivalent to 26.05 inches of runoff from the upstream drainage area. The maximum discharge was measured as 101,000 cfs on May 20, 1960. An average daily inflow of 76,600 cfs occurred on May 3, 1992.