 The Missouri basin suffered a series of catastrophic floods around the turn of the 20th century , most notably in 1844 , 1881 , and 1926 – 1927 . In 1940 , as part of the Great Depression @-@ era New Deal , the U.S. Army Corps of Engineers ( USACE ) completed Fort Peck Dam in Montana . Construction of this massive public works project provided jobs for more than 50 @,@ 000 laborers during the Depression and was a major step in providing flood control to the lower half of the Missouri River . However , Fort Peck only controls runoff from 11 percent of the Missouri River watershed , and had little effect on a severe snowmelt flood that struck the lower basin three years later . This event was particularly destructive as it submerged manufacturing plants in Omaha and Kansas City , greatly delaying shipments of military supplies in World War II . 
