Lake Wappapello is a reservoir on the St. Francis River, formed by Wappapello Dam (36°55′55″N 90°16′45″W / 36.93194°N 90.27917°W). Created in 1941, this 8,400-acre (34 km2) lake is located 120 miles (190 km) south of St. Louis, Missouri. The reservoir lies mostly in Wayne County, but its southernmost reaches (near the dam) extend into northern Butler County, both in Missouri. Both the dam and reservoir are owned and operated for the public by the United States Army Corps of Engineers.