The Bighorn River is rated one of the world’s finest trout streams because of its abundant trout, dense insect hatches, and easy accessibility. Prior to 1965, the Bighorn was a warm, silty stream that flowed out of the spectacular Bighorn Canyon northward into the eastern Montana prairie. With the completion of Yellowtail Dam at Fort Smith, Montana, most of the river’s silt load was trapped behind the dam. The river below was transformed into a cold, clear tailwater, much like a giant spring creek - an ideal habitat for trout.

The Bighorn River’s headwaters lie in the Absaroka, Bighorn, and Wind River mountain ranges of northwest and north central Wyoming. From below the Montana-Wyoming state line, the mainstem flows through Bighorn Canyon to Yellowtail Dam, a 47-mile-long passage between the northern end of the Bighorn Mountains and the southeast margin of the Pryor Mountains. The canyon, its sandstone and limestone cliffs rising steeply hundreds of feet, holds the waters of Bighorn Lake. From the Afterbay Dam, a reregulating facility 2 miles downstream, the Bighorn River journeys 84 miles - through the Crow Indian Reservation, past massive tree-dotted ramparts and rock outcroppings, beside rolling hills, grasslands, and pine-covered ridges - and joins the Yellowstone River near the old settlement of Bighorn, just east of Custer, Montana.