Tongue River Dam

The Tongue River Dam 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.

The earthen dam was constructed in the river canyon in 1939, with a height of 91 ft and a length at its crest of 1824 ft. 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 mi riverine reservoir it creates has a normal water surface of 5.5 mi2, a maximum capacity of 150000 acre feet, and normal storage of 69400 acre feet. Recreation includes boating, fishing for bass, crappie, walleye and northern pike, and camping in the Tongue River Reservoir State Park. For white-water rafters, the Tongue is a Class I river from the Dam downstream (northward) to its confluence with the Yellowstone River.