[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.