The Bighorn River is a body of water that is legendary in the fly fishing world. Thirteen miles of unparalleled fishing opportunity awaits, stretching from the Yellowtail Dam in Fort Smith, bubbling along to the private boat launch at the Bighorn River Lodge. Prepare yourself for spectacular views of lands entrenched in American history. For a change of pace, fish the river below the Bighorn River Lodge and enjoy more secluded fishing opportunities. In the evenings, cast off the private launch area for the evening hatch, or try your luck on the BRL private ponds.
A Lesson in Geography and History of the Bighorn River
The Bighorn River is born in the Owl Creek Mountains in Wyoming, just southeast of Yellowstone National Park. It joins the Yellowstone River 336 miles downstream near Custer, Montana. From its origin, the river flows in a southeasterly direction until it encounters the Bighorn Mountains where it turns north and runs parallel to the mountain’s western edge. It cuts through the mountain range and forms the breathtaking Bighorn River Canyon which straddles the Wyoming-Montana state line. After exiting the canyon, the river runs north another 84 miles to its confluence with the Yellowstone.
From its origin in the upper section, it is known as the Wind River until it reaches a point called “The Wedding of the Waters.” The waters below that point are referred to as the Bighorn River. Hence, the Wind River of Wyoming and the Bighorn River of Montana are really the same stream.
In 1965, the Yellowtail Dam was constructed at the mouth of the canyon, creating the Bighorn Reservoir. The purpose of the reservoir was to provide electric power, flood control and irrigation for the valley below.
Fort Smith, located directly below the dam, was built near the original site of Fort C.F. Smith, a military post that played a significant role in the history of the Bozeman Trail and frontier expansion.
Prior to the construction of the dam, the Bighorn River was primarily a warm water fishery as it exited the canyon. After the dam was completed, the fishery was radically altered, creating what has now become the only Blue Ribbon trout stream in southeastern Montana.
The Bighorn River is a fantastic tailwater fishery flowing through a valley filled with inspired scenery that is home to the Crow Indian Reservation. Several elements can be attributed to the development of this almost “magical” river, prolific with trout. At the heart of it all is the controlled temperature of the water.
Water flows from the Bighorn Reservoir into the river from a depth of around 500 feet. The water temperature remains a consistent 40-55’, ideal for trout. During the hot days of summer, the depth at which the water exits the dam helps keep the water cool. The water temperatures may rise into the lower 60’s at which time the trout move up into shallow riffles where the fast moving water provides more oxygen and more food. During winter, the water may get cooler but because of the dam the river never freezes. In winter, fish find their way into slow, deep pools where they can conserve energy. The fish tend to stay in the deep pools waiting until water temperatures rise again in the spring. The uniqueness of the reservoir allows angler to fish the Bighorn year round.
Nutrients are another essential ingredient for a successful trout population. The giant limestone and sandstone walls of the Bighorn Canyon add vital nutrients to the water as it flows through the immense 74 mile long reservoir. These nutrients promote prolific aquatic plant growth. The grass and algae, which occasionally proves frustrating to anglers, create habitat for aquatic invertebrates and insects which are essential food sources for trout and include midges, baetis, scuds and sowbugs. These are supplemented by grasshoppers and other terrestrials during the warmer months. Brown and Rainbow Trout are not the only fish to benefit from the ideal conditions of the river. Other game fish found in the Bighorn River include Mountain Whitefish and Goldeneye. Further downstream, the moderating affect of the dam diminishes, but not until it has created one of the most prolific tailwater fisheries in the world.