Tongue River Dam

The Tongue River Dam (National Inventory of Dams ID MT00002) is a dam in Big Horn County, Montana, a few miles north of the Wyoming state border. It impounds the Tongue River, creating the Tongue River Reservoir.

Tongue River Reservoir
Tongue River Dam
Tongue River Reservoir
Location	Big Horn County, Montana
Coordinates	45°03′38″N 106°47′24″W [1]
Lake type	Reservoir
Primary inflows	Tongue River
Primary outflows	Tongue River
Basin countries	United States
Max. length	5.5 miles (8.9 km)
Max. width	1.1 miles (1.8 km)
Surface area	3,700 acres (1,500 ha)
Water volume	79,071 acre-feet (97,533,000 m3)[2]
Surface elevation	4,222 feet (1,287 m)[1]

The earthen dam was constructed in the river canyon in 1939, with a height of 91 feet (28 m) and a length at its crest of 1,824 feet (556 m).[2] It impounds Montana's north-flowing Tongue River for flood control and irrigation water storage. The dam and reservoir are owned and operated by the Montana Department of Natural Resources and Conservation.

The 12-mile-long (19 km) riverine reservoir it creates has a normal water surface of 5.5 square miles (14 km²), a maximum capacity of 150,000 acre-feet (190,000,000 m³), and normal storage of 69,400 acre-feet (85,600,000 m³).[2] Recreation includes boating, fishing for bass, crappie, walleye and northern pike,[3] and camping in the Tongue River Reservoir State Park.[4] For white-water rafters, the Tongue is a Class I river from the Dam downstream (northward) to its confluence with the Yellowstone River.[5]