Tenkiller Ferry Lake, or more simply, “Lake Tenkiller,” is a reservoir in eastern Oklahoma formed by the damming of the Illinois River. The earth-fill dam was constructed between 1947 and 1952 by the United States Army Corps of Engineers for purposes of flood control, hydroelectric power generation, water supply and recreation. It went into full operation in 1953. The lake and dam were named for the Tenkiller family, prominent Cherokees who owned the land and ferry that were bought for the project. This is 6th largest lake in Oklahoma, based on water capacity.