Susquehanna (səskwĭhănˈə) [key], river, 444 mi (715 km) long, rising in Otsego Lake, at Cooperstown, N.Y., and zigzagging SE and SW through E central Pa. to Chesapeake Bay near Havre de Grace, Md. The bay is the drowned lower course of the river. The West Branch (c.160 mi/260 km long), which rises in the Allegheny Mts., W Pa., and follows a circuitous course eastward to Sunbury, Pa., is the river's chief tributary. The Susquehanna River traverses an anthracite coal region; the many significant mining and industrial cities on its banks were forced to scale down production as the steel and coal industries declined in the early 1980s. These include Binghamton and Oswego, N.Y., and Pittston, Wilkes-Barre, Harrisburg, and Scranton (on the Lackawanna tributary), Pa. The shallow, swift-flowing river is unsuited for navigation. Several hydroelectric power plants are located on the Susquehanna; the Conowingo plant (Md.) is one of the largest nonfederal power stations in the nation. The Susquehanna and its tributaries have extensive flood control works. However in June, 1972, the river, swollen by the torrential rains of Hurricane Agnes, breached 40-ft (12-m) dikes in places and flooded most of the basin, causing one of the greatest flood disasters in U.S. history.