The name originates from the ‘Beaverhead Rock’, a rock located on the river between Dillon and Twin Bridges, that was named by Sacajawea during the Lewis & Clark Expedition. The river originates at the outflow of Clark Canyon reservoir, about 20 miles south of Dillon, and flows north where it meets with the Big Hole in Twin Bridges, Montana. The Beaverhead is a much smaller river than the neighboring Big Hole, its banks lined with willows that provide nice cutbanks as it winds through the valley.
The Beaverhead is a tail-water fishery with prolific hatches of caddis, mayflies, yellow sallies and midges. All of these bugs create a massive food source for the fish, resulting in fat, healthy trout. During the hot summer months, the fish also enjoy terrestrials such as: hoppers, ants, and beetles. Occasionally aggressive trout will eat mice and frogs, and chase large craneflies skated across the surface of the water. In addition to the nearly year long dry fly action, a fisherman can have good luck dropping nymphs in the deep holes in the upper river. Spring and fall produce terrific streamer fishing, especially in the less crowded stretches of the river near Dillon.