CENTRAL MISSOURI RIVFR DRAINAGE 



Boundaries: Smith River to Fork Peck Reservoir 

 Drainage size: 40,987 square miles 

 Tributaries: Smith, Judith, Musselshell 

 Main stem length: 251 miles 

 Cities/Towns: Great Falls, Fort Benton 

 Access: U.S. Highways 87 and 191 



The Missouri remains wide and lazy for 32 miles after it is 

 joined by the Smith River, but is then transformed into a seething 

 mass of Whitewater as it plunges over a series of five bedrock 

 cascades that earned the name Great Falls. Described by Lewis in 

 1805 as "the greatest sight I ever beheld .. . a sublimely grand 

 spectacle," these rapids forced the expedition to portage tons of 

 gear for nine miles. Today, hydroelectric dams at the lip of each 

 waterfall have significantly altered their character. The only 

 major Whitewater on the Missouri is just below Maroney Dam. Other 

 "rapids" downstream are, by comparison, mere riffles. 



The Missouri River from the Smith to its confluence with the 

 Musselshell River is noted for the waterfalls at Great Falls, the 

 white cliffs, and, farther downstream, the Missouri Breaks -- an 

 area of weathered shale, along with isolated sandstone cliffs and 

 associated grassland, ponderosa pine, and juniper communities. The 

 forested mountain islands that rise up from the prairie and empty 

 into the Missouri drainage include the Big Snowy, Little Snowy, 

 and Highwood Mountains. Like many mountains in eastern Montana, 

 the Judith, Moccasin, Crazy, and Castle ranges were formed when 

 intrusions of igneous rock cut through the sedimentary floor of 

 the Northern Great Plains. 



One of the most significant waterways in the settlement of 

 American west, the Missouri gradually carves its way through the 

 infamous Missouri "breaks" for nearly 170 miles until it meets 

 Fort Peck Reservoir (Figure 10). Following a decade of bitter 

 conflict, the wild character of the last major free-flowing 

 stretch of this historic river finally was assured in 1976 when 

 Congress designated this section part of the National Wild and 

 Scenic River System. 



Paralleling the Missouri to the south, the Musselshell River 

 flows eastward for 364 miles from central Montana mountain ranges, 

 one of the longest river journeys in the state, before entering 

 the Missouri above Fort Peck Reservoir. The over-appropriation of 

 the Musselshell's water through an extensive series of ditches, 

 canals, reservoirs, and main stem diversion dams has resulted in a 

 recording of zero flow at Mosby in over half the fifty years the 

 U.S. Geological Society has been recording flows. 



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