Lake Wister is located in the San Bois Mountains on the Poteau River -- the only river that flows north in Oklahoma. The project was designed and built by the Tulsa District Corps of Engineers.
Authorization: Flood Control Act approved June 28, 1938, Committee Document No. 1, 75th Congress, 1st Session. The conservation pool elevation for December 1 to May 31 was changed by the 98th Congress in Public Law 98-63 dated July 30, 1983. The Water Resource Development Act of 1996 permanently raised the lake level by 3.5 feet, making the level 478 feet.
Location: On the Poteau River at river mile 60.9, about 2 miles south of Wister in LeFlore County, Oklahoma.
Purpose: Flood control, water supply, low flow augmentation, water conservation, and sedimentation.
History of Construction: Construction started in April 1946 and was completed in May 1949; embankment closure started in June 1948 and was completed in May 1949; and impoundment of the conservation pool started in October 1949 and was completed in December 1949. The project was completed for full flood control operation in October 1949. Major rehabilitation of the embankment was completed in 1990.
Type of Structure: The dam is a rolled, impervious earth-filled embankment with rock-protected slopes. The dam is 5,700 feet long and rises to a maximum height of 99 feet above the streambed. Oklahoma State Highway 270 is located along the top of the dam. A rolled, earthfill dike which extends from the right abutment is 2,400 feet long and rises to a maximum height of 40 feet.
Spillway & Outlet Works: An uncontrolled, concrete, chute-type spillway with modified broad-crested weir is located in a ridge which extends downstream from the right abutment of the main embankment. The spillway has a total width of 600 feet. Spillway capacity is 170,910 cubic feet per second at maximum pool (elevation 523.5). The outlet works consist of two 15.8 by 14.0-foot egg-shaped conduits located in the valley adjacent to the right abutment of the dam. Capacity of the outlet works varies from 14,600 cfs at the top of the flood control pool to 7,900 cfs at the conservation pool elevation. Flows are regulated by six 7- by 12-foot tractor-type, vertical-lift gates located in a concrete gate tower. Low-flow regulation is provided by a 30-inch-diameter gated pipe conduit. Two water supply intakes are located in the gate tower; one for possible future water supply use and the other to supply the project. Controlling bank-full capacity below the dam is 6,600 cfs.
Hydrologic Data: The flood of record occurred on June 18, 1934, with a peak discharge of 81,000 cfs. The largest total volume, 567,000 acre-feet, occurred in April 1927. Total runoff during that period was 10.71 inches.