In the summer of 2011, the Missouri river caused floods in Montana to Missouri. Record snowfall and rain in the Rocky Mountains caused six major dams to release water at levels more than double the previous record. On May 1, 2011, Gavins Point Dam in Yankton, S.D. released 45,000 cubic feet of water per second. By the end of the month, 77,000 was release and in June and July, 160,700 cubic feet per second was released. That huge amount of water forced an already swollen Missouri to spill it banks in the Sioux City, Iowa metro area, which includes Dakota Dunes, S.D. and South Sioux City, Neb.