Fly Fishing the Bighorn River. Hale Harris

      Bighorn River (Montana)

       Location: Montana’s Bighorn flows northeastward through the Crow Indian Reservation, where 75 miles later it joins the Yellowstone River near the town of Custer, Montana. People commonly fly into Billings, Montana, or Sheridan, Wyoming (95 miles). There is also a paved airstrip in the vicinity of Afterbay Dam for those with private aircraft.

      The Bighorn River is one of the most famous trout destinations in the United States. Created in 1967 by the completion of Yellowtail Dam, this former large prairie river was transformed into a trout-fishing paradise. The most productive trout fishing is found on the upper 20 miles of the river below Afterbay Dam, although fishable trout populations exist downstream of Hardin, Montana.

      The Bighorn is a large river, and flows of 2,500 to 4,000 cfs are considered normal. It is very rare that the river becomes unfishable due to water conditions, and it is a popular destination when other Montana rivers are high and muddy due to spring runoff. During an average year, the Bighorn will experience higher flows in late May and June, but water clarity remains excellent and fishing productive on a variety of fly patterns.

      The river’s water chemistry is highly alkaline, contributing to the growth of algae and aquatic grass. Think of the Bighorn as a giant spring creek. An abundance of crustaceans, such as scuds

      and sow bugs, along with prolific insect hatches, create a super-fertile fish environment. Trout growth rates are impressive, and fish in the 14- to 16-inch range are common. Fish 20 inches and over are not rare. Brown trout are the dominant species, but rainbows are numerous as well. While the river’s rainbows are highly prized, the sheer numbers of brown trout make this river unique. Bighorn browns are renowned for their sporting qualities. They are very strong, leap well when hooked, and tend toward golden hues in coloring. The river has excellent spawning habitat, and is managed by the State of Montana as a wild-trout fishery. There is no stocking program.

      The midge hatch kicks off the dry-fly season. Midges can be found throughout the year, but the months of April and

      May are prime time. Anglers take fish on a variety of adult midge and emerger patterns, but cluster patterns work well when the hatch is heavy.

      Late April sees the beginning of the Baetis mayfly hatch, and these insects continue through May and into June.