Tongue River Reservoir State Park is an isolated location 6 miles north of Decker, Montana, a town that is a couple of miles north of the Wyoming border, on Secondary 314, and then 1 mile east on a county road. Tongue River Reservoir is a 12-mile long reservoir, or lake, that provides water activities within one of the most scenic locations of all of Montana. You will be mystified by its red shale formations, and its juniper treed canyons. Both black crappies and white crappies are found in the lake. The fishing and water sport opportunities can make the trip to the state park very pleasurable.
Tongue River State Park is open year around and does have a fee and camping restrictions.
The Bighorn Canyon National Recreation Area is one of the lesser known treasures of this the Treasure State. I have not fished the scenic Bighorn Lake, or the nearby Afterbay Lake that is below the Yellowtail Dam, or the Bighorn River, but I understand that it, the fishing, in certain spots is " world-class."
The Yellowtail Dam is named after the famous Crow chairman Robert Yellowtail. The Big Horn National Recreation Area is composed of greater than 70,000 acres which straddles the northern Wyoming and southern Montana borders. The north end of Bighorn Canyon is surrounded by the Crow Indian Agency land. And it is important that you do not travel by auto, or disembark by boat, on Indian Agency land where not allowed. As for the south end, it can be traveled by auto or boat.
The area has water sports, fishing, ice fishing, camping and hiking capabilities depending on the season, and its seasonal policy.
a personal sketch
See Disclaimer @ Eastern Montana .. a perspective of a former resident and frequent visitor