Big Falls (Missouri River waterfall)
Big Falls is a major waterfall located on the Missouri River in western Montana in the United States. It is the lowermost and largest of the Great Falls of the Missouri, at high and up to wide at peak flow. Although the falls used to flow powerfully year-round, most of the water is now diverted to the 60 megawatt hydroelectric plant of upstream Ryan Dam, reducing it to a trickle in the summer months. Grand Falls was named by William Clark of the Lewis and Clark Expedition in 1805.