The Washita River is one of Oklahoma's longest rivers, stretching approximately 626 miles, with 580 miles within Oklahoma state boundaries. Originating in the Texas panhandle, the river flows generally southeast until it reaches Lake Texoma near Tishomingo in Johnston County. Prior to the construction of Denison Dam in 1946, the Washita joined the Red River near Platter in Marshall County. Today, the Washita River effectively ends where Lake Texoma begins. The river has a well-documented history of periodic flooding, which has created numerous oxbows and cutoff lakes along its course. These natural wetlands were historically the only ponds or lakes within Oklahoma before man-made impoundments were constructed, and they remain important habitats for wildlife, particularly migrating waterfowl.