The impounded Tongue River provides a 12-mile long reservoir set in the scenic red shale and juniper canyons and open prairies of southeast Montana. Large bodies of water such as this are rare in this prairie country, and 50,000 visitors each year flock to enjoy the recreation. Boating and other water sports are popular here, and the park boasts excellent bass, crappie, walleye, and northern pike fishing. Four state-record fish have been caught in these waters. The park is one square mile in extent and has vault toilets, boat rentals, picnic tables, groceries, public phone and LP gas refills. Camping is limited to 14 days out of a 30-day period. There is a day use charge and a camping charge.
The park is 7 miles from Decker, nearly on the border with Wyoming.