Bighorn River Fishing Report
Date: 09/08/2025
Posted by: Toby SwankCurrent Conditions
The Bighorn River is fishing well as we ease into September, holding steady with consistent opportunities across a range of techniques. Morning sessions remain your best window, both for comfort and for action, with hatches lining up and trout feeding actively before the heat sets in.
Trico activity has taken over as the dominant hatch. These tiny mayflies are thick in the early hours, and trout have been sipping them confidently in the slower runs, particularly below 3-Mile. It’s technical fishing: size 20–22 dries, long leaders, fine tippet, and a dose of patience.
Caddis have been making stronger showings through the afternoon. Fish are starting to look up in the riffles, particularly where there’s a bit of shade or overhead cloud cover. There’s a nice mix of tan and black caddis still fluttering around, and in the right water, that hatch is enough to get trout moving.
Terrestrial season isn’t quite over, either. Hoppers aren’t the main course anymore, but they’ll still draw a strike when fish aren’t keyed in on the bugs. A big dry with a small dropper, a pheasant tail, or prince, has been a dependable combination, especially when working through slightly off-color water near the edges or around submerged vegetation.
Nymphing is carrying most of the weight right now. Sowbugs and scuds are the ticket, substituted with PMD emergers or zebra midges.
Streamer fishing has been spotty, but it’s still worth the effort in low-light windows. Early mornings and late evenings are best, especially with smaller baitfish imitations like sparkle minnows or skiddish smolts. It’s not a numbers game, but when a brown moves, it’s usually with purpose.
All in all, the Bighorn is in a good rhythm right now. Tricos are keeping things exciting in the morning, caddis and terrestrials offer variety through the day, and subsurface options are as steady as ever.
Additional Resources:
- September fly fishing guide to the Bighorn River
- Bozeman fly fishing guide to September
Stream Flows
Flows
Recommended Flies
Black Zebra Midge
Orange Scud
PMD Jigster
Sweetgrass Hopper
Black Lite Brite Perdigon
Tailwater Sowbug
Skiddish Smolt
PMD Crackback
Bighorn River Fly Fishing
The Bighorn River, emerging from the base of Afterbay Dam near Fort Smith, Montana, is one of the state’s premier tailwater fisheries. Fed by cold, consistent flows from Yellowtail Dam, the river offers exceptional fly fishing opportunities across the first 35 miles—especially between the Afterbay and Bighorn Fishing Access Sites.
The most popular stretch is the 10-mile float from 3-Mile to Bighorn Access. Here, anglers find productive seams, riffles, and side channels that are ideal for both floating and wade fishing. Dry fly action peaks during PMD and BWO hatches, while nymphing remains effective year-round.
Crowds are common from spring through early fall, particularly in the first three miles below the dam and at the 3-Mile fishing access site. This easily wadeable section includes legendary runs like the Breakfast Hole and Hot-Dog Run, where trout stack up in knee-deep gravel-bottomed riffles.
Further downstream, fishing pressure decreases and trout numbers taper off, but float anglers willing to explore these more remote stretches will find reprieve from the crowds.. Late summer and fall can be tricky due to aquatic vegetation and irrigation returns.
Whether you're casting dries, drifting nymphs, or stripping streamers, the Bighorn delivers consistent action for wild brown and rainbow trout—making it a must-visit for serious fly anglers in Montana.
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