The Republican River, Saline River, Solomon River, and Smoky Hill River all go east through the Smoky Hills. This is because they start in the High Plains. Starting in the 1940s, the U.S. Army Corps of Engineers and the U.S. Bureau of Reclamation dammed these rivers at points in the Smoky Hills for flood control and irrigation reasons. This created many reservoirs. These include Cedar Bluff Reservoir, Kanopolis Lake, Kirwin Reservoir, Waconda Lake, Webster Reservoir, and Wilson Lake.