Tongue River Reservoir

Tongue River Reservoir State Park encompasses 640 acres around a 12-mile-long reservoir in Big Horn County in southeastern Montana. The reservoir provides excellent warm-water fishing and recreation in the scenic sandstone country near the Northern Cheyenne Reservation.

The reservoir supports walleye, smallmouth bass, largemouth bass, channel catfish, and crappie. Mule deer and pronghorn inhabit the surrounding terrain. Raptors including golden eagles hunt the grasslands, and waterfowl congregate on the reservoir.

Ponderosa pine grows on sandstone outcrops and north-facing slopes. Sagebrush and native grasses cover the drier terrain. Juniper dots the landscape. Cottonwoods line the Tongue River above the reservoir.

The reservoir was created by Tongue River Dam on the Tongue River, which flows north from the Bighorn Mountains. The surrounding terrain features eroded sandstone formations of the Fort Union Formation, creating scenic badlands-like landscapes.

Southeastern Montana experiences hot, dry summers and cold winters. Annual precipitation averages about 14 inches. The reservoir area can be very hot in summer with temperatures exceeding 100°F.

The Tongue River area is historically significant to the Northern Cheyenne people. The Battle of the Tongue River occurred during the Indian Wars. The reservoir was built in 1939 for irrigation.

Tongue River Reservoir State Park was developed around the irrigation reservoir to provide recreation in southeastern Montana. The park has become one of the state's premier warm-water fishing destinations.

Fishing for walleye and smallmouth bass is excellent. Boating and swimming provide summer recreation. The scenic sandstone terrain and ponderosa pine add character. Camping serves overnight visitors.

The park offers camping, boat ramps, and day-use facilities at multiple sites around the reservoir. It is located about 6 miles north of Decker on a county road, approximately 60 miles south of Miles City.

Water management balances irrigation and recreation. Fish management maintains diverse warm-water populations. The park provides important recreation access in a sparsely populated region.