There are at least 3,223 named lakes and reservoirs in Montana, including Flathead Lake, the largest natural freshwater lake in the western United States. Other major lakes include Whitefish Lake in the Flathead Valley and Lake McDonald and St. Mary Lake in Glacier National Park. The largest reservoir in the state is Fort Peck Reservoir on the Missouri river, which is contained by the second largest earthen dam and largest hydraulically filled dam in the world. Other major reservoirs include Hungry Horse on the Flathead River; Lake Koocanusa on the Kootenai River; Lake Elwell on the Marias River; Clark Canyon on the Beaverhead River; Yellowtail on the Bighorn River, Canyon Ferry, Hauser, Holter, Rainbow; and Black Eagle on the Missouri River.