MUSSELSHELL RIVER

river, rising in the Crazy Mountains in the Gallatin and the Lewis and Clark national forests, in Meagher county, central Montana, U.S., and flowing 292 miles (470 km) east and north past Harlowton and Roundup to Fort Peck Lake, a huge reservoir dammed on the Missouri River, in northwest Garfield county. A small headstream is impounded near Martinsdale to form an irrigation reservoir. The river was named Musselshell by the explorers Meriwether Lewis and William Clark in 1805, when they found freshwater mussels on its banks.