Fishing the Bighorn River of Montana

The Bighorn River has more fish per mile than almost any river in Montana.

Although 2023 was a strange year on the Bighorn, the fish seemed to have really flourished.   The Bighorn River always goes through cycles, and what a great stage of the cycle we should be in for in 2024!  There is currently an older age group of both Rainbows, and Browns.  This group of fish will more likely take you into the backing than not.  They are hot, fat fish that average 17-22 inches, with the big guy for the season reaching the upper 20's.  Now, there are not a ton of these fish, but there is a great younger generation browns coming up, and they are growing fast.  These prolific fish will keep you very entertained, and it is a great sign for the future.  The richness of bug life is ensuring that these guys are growing as quickly as possible.  We expect these fish to average between 14-16 inches by the spring.   
Historically the Bighorn River has a population dynamic of roughly 60% Browns and 40% rainbows, the upper stretches of the Bighorn supports as many as 6,000 trout per mile. As a tailwater, the Bighorn’s relatively stable water temperature provides the insects and fish in the river ideal feeding and growing conditions. The Bighorn river trout tend to proliferate year-round which keeps the Bighorn fish growing all year.


Average size of Bighorn trout is in the 14 –16 inch range, with many fish running close to 20 inches, and the big fish being as large as 28 inches. The high alkalinity and consistent water temperature support a very diverse and prolific food base for trout, that consists of midges, various mayfly and caddis genus, one stonefly genus, crustaceans such as scuds and sow bugs, aquatic worms, leeches and minnow varieties. Terrestrial insects such as grasshoppers, beetles and ants are also important food items that are aggressively eaten by trout during the summer months.

Insect hatches on the river are dramatic, in both size and duration. The first hatches of the year are midges, followed   by Blue-winged Olive and Pale Morning Dun mayflies, black and tan caddis, stoneflies, Tricorythodes mayflies, and ending with the Pseudocleon mayflies in the fall.

Now, do not take this the wrong way, but one of our favorite side trips at this lodge is going up to the Yellowtail Canyon and Reservoir.  We go up here with our jet boat and fish for big carp on dry flies.  Not only is it one of the prettiest places you will fish, the slow take of carp as it tries to get that fly in its mouth will test the most patient fisherman.  When they feel the hook, they will dive down and push your tippet to the max.  Do not try to land these fish too quickly!  It can add a great piece of variety to your time at the lodge. The small mouth bass fishing is also fun.

Bighorn River fly fishing for Carp

As with our operations, Sweetwater works with some of the finest guides on the Bighorn. They are adept teachers and will help you navigate the complexities of the hatches and the fishery. Your day will typically employ nymph fishing, emerger fishing, and mind-bending dry fly fishing. It is truly a classroom for the trout fisherman.