During the 20th century , the Missouri River basin was extensively developed for irrigation , flood control and the generation of hydroelectric power . Fifteen dams impound the main stem of the river , with hundreds more on tributaries . Meanders have been cut and the river channelized to improve navigation , reducing its length by almost 200 miles ( 320 km ) from pre @-@ development times . Although the lower Missouri valley is now a populous and highly productive agricultural and industrial region , heavy development have taken its toll on wildlife and fish populations as well as water quality .