Western Montana Fly Fishing Report
Current Restrictions and Closure Summary
There are currently no hoot-owl restrictions listed by Montana FWP on the Bitterroot, Blackfoot, Clark Fork, Rock Creek, or West Fork Bitterroot.
- Blackfoot River: Closed to floating from Weigh Station Fishing Access Site downstream to the point where the river crosses beneath Interstate 90 because of railway bridge construction.
- Temperature awareness: The absence of a legal restriction does not mean every section should be fished all afternoon. Continue carrying a stream thermometer, particularly early in the week.
- Check daily: Emergency restrictions and closures can change quickly. Check Montana FWP before every trip or launch.
Regional River Conditions Overview
The Bitterroot, Blackfoot, Clark Fork, Rock Creek, and West Fork remain in low, clear late-summer condition. Trout are still concentrated around riffle edges, shaded banks, deeper slots, foam lines, broken water, pocket water, and areas with stronger current.
The big change this week is weather. Monday and Tuesday remain warm, but Wednesday brings a sharp cooldown with clouds and showers. Thursday stays cool, and Friday brings another good chance of clouds and showers. That weather should cool the rivers, reduce bright-light pressure, and begin shifting feeding activity away from the strictly early-morning schedule we have been stuck with most of August.
Expect Tricos early, terrestrials through the warmer parts of the day, and increasingly important Hecubas, Mahoganies, and BWOs during cloudy periods. Streamer fishing also becomes much more interesting Wednesday through Friday.
Bitterroot River
Conditions
The Bitterroot remains low and clear but is entering a much better weather pattern. Latest available readings are around 454 CFS near Darby, 280 CFS at Bell Crossing, and 675 CFS near Missoula. The upper river has enough water to provide good riffle and pocket-water habitat, while the middle and lower river remain technical. Cooler weather Wednesday through Friday should noticeably improve the fishing window.
Where to Fish
- Riffle edges and transitions into deeper water
- Foam lines along inside bends
- Shaded banks and undercut grassy edges
- Tailouts during morning Trico activity
- Deeper slots beside faster current
- Soft seams during cloudy Hecuba or BWO activity
How to Fish It
- Start with Trico spinners in slower morning feeding lanes
- Use 5X–6X and longer leaders when fish are feeding selectively
- Prospect grassy banks with hoppers, ants, and beetles after the morning mayfly window
- Fish a small Perdigon, Frenchie, or mayfly nymph below a terrestrial
- Watch carefully for Hecubas as clouds arrive Wednesday and Friday
- Carry Mahogany and BWO patterns as cooler weather settles in
- Streamer fish shaded banks, deeper buckets, and structure during cloudy periods
Top Patterns
- Trico spinner, size 18–22
- Hecuba or large rusty mayfly, size 10–12
- Mahogany Dun, size 14–16
- BWO dry or emerger, size 18–22
- Caddis dry, pupa, or soft hackle, size 14–18
- Hopper, ant, or beetle, size 8–18
- Olive, black, or tan streamer, size 4–8
Blackfoot River
Conditions
The Blackfoot near Bonner is around 613 CFS. It remains low but fishable, with cooler overnight temperatures helping conditions. Hopper and attractor fishing remain important, while caddis and scattered Tricos provide smaller-fly opportunities. The cooler, cloudier weather later this week should improve streamer fishing considerably.
Where to Fish
- Boulder edges and plunge pools
- Fast riffle edges
- Shaded banks and deeper buckets
- Foam lines below structure
- Grassy banks for terrestrial fishing
- Inside seams below heavier current
How to Fish It
- Prospect with hoppers and attractor dries along banks and boulders
- Drop a caddis pupa, mayfly nymph, or jig fly beneath the dry
- Fish ants and beetles in slower bank water
- Watch for localized Trico activity in softer morning water
- Streamer fish aggressively during Wednesday and Friday cloud cover
- Start watching for the first meaningful October Caddis activity as September begins
- Plan floats around the active Weigh Station to I-90 closure
Top Patterns
- Hopper or foam attractor, size 8–12
- Ant or beetle, size 12–18
- Trico spinner, size 18–22
- Caddis dry or pupa, size 14–18
- Perdigon or jig nymph, size 14–18
- October Caddis pupa or large caddis attractor
- Olive, black, tan, or white streamer
Clark Fork River
Conditions
The Clark Fork is around 1,110 CFS above Missoula and around 1,780 CFS below Missoula. This river becomes increasingly interesting as September begins. Tricos remain important early, hoppers continue to produce between hatches, and the first serious fall mayfly opportunities are beginning to develop. Wednesday and Friday could be particularly good if clouds and showers materialize.
Where to Fish
- Soft morning feeding lanes during Trico activity
- Riffle edges and foam lines
- Grassy banks and undercut edges
- Tailouts and long slicks where fish pod up
- Side channels with depth and current
- Deeper banks and structure during cloudy streamer windows
How to Fish It
- Head hunt with Trico spinners early
- Prospect hoppers and terrestrials between hatch windows
- Watch for Hecubas, Mahoganies, and BWOs as cloud cover develops
- Use longer leaders and careful presentations around feeding pods
- Nymph riffle edges with mayfly and caddis patterns when fish are not rising
- Streamer fish aggressively during cloudy and showery periods
Top Patterns
- Trico spinner, size 18–22
- Hecuba, size 10–12
- Mahogany Dun, size 14–16
- BWO dry or emerger, size 18–22
- Hopper, ant, or beetle, size 8–18
- Caddis dry or pupa, size 14–18
- Olive, black, or tan streamer
Rock Creek
Conditions
Rock Creek near Clinton is around 255 CFS, almost exactly in its normal late-August range. The creek is low, clear, highly wadeable, and technical. September is one of the better times to fish Rock Creek as traffic eases and fall insects begin joining the remaining terrestrials.
Where to Fish
- Riffle edges and oxygenated pocket water
- Boulder cushions and soft pockets
- Shaded willow edges and cutbanks
- Tailouts during Trico activity
- Foam lines below faster runs
- Deeper buckets for cloudy-day streamer fishing
How to Fish It
- Fish Tricos in soft morning seams and tailouts
- Prospect with hoppers, ants, beetles, and attractor dries
- Use small dry-dropper rigs through pocket water
- Carry Hecubas, Mahoganies, and BWOs as September begins
- Streamer fish deeper buckets during cooler cloud cover
- Use stealth and make the first cast count in skinny water
Top Patterns
- Trico spinner, size 18–22
- Hecuba, size 10–12
- Mahogany Dun, size 14–16
- BWO dry or emerger, size 18–22
- Hopper, ant, beetle, or attractor, size 8–18
- Caddis, size 14–18
- Olive or black streamer, size 4–8
West Fork of the Bitterroot
Conditions
The West Fork near Conner is around 354 CFS, which is a healthy managed late-summer flow and above its typical late-August median. The West Fork remains a strong smaller-water choice, especially for anglers looking for clear water, cooler mornings, and technical dry-fly fishing.
Where to Fish
- Shaded riffle edges below Painted Rocks
- Protected tailouts and inside seams
- Foam lines beside structure
- Deeper pockets below wood and boulders
- Soft glides during Trico activity
- Overhanging grass and banks for terrestrials
How to Fish It
- Start with Trico spinners in soft morning water
- Use longer leaders and 5X–6X when fish are selective
- Prospect with ants, beetles, and small hoppers
- Use small dry-dropper rigs through riffles and pockets
- Watch for Hecubas during cooler, cloudier periods
- Make careful first casts before stepping into productive water
Top Patterns
- Trico spinner, size 18–22
- Hecuba, size 10–12
- Caddis dry or pupa, size 14–18
- Small foam attractor, size 12–16
- Ant or beetle, size 12–18
- Small hopper, size 10–14
- Small olive streamer
Planning Note
This week marks the first meaningful shift toward fall fishing. Monday and Tuesday remain warm enough that an early start still makes sense. Wednesday changes everything: cooler temperatures, clouds, and showers should improve both water temperatures and daytime feeding activity.
Wednesday through Friday, do not automatically assume the best fishing ends at 11:00 a.m. Watch the river. Hecubas, Mahoganies, and BWOs may bring fish up later in the day, particularly on the Bitterroot, Clark Fork, and Rock Creek. Cloud cover should also make streamers much more productive.
The best overall strategy is Tricos early, terrestrials between hatches, fall mayflies when clouds develop, and streamers when the light gets dark.
River Flow Snapshot – August 31, 2026
Values are the latest available readings reviewed August 31. Most gauges reported August 29–30. USGS readings are provisional and may change.
| River | Section | Gauge | Flow (CFS) | Status |
|---|---|---|---|---|
| Bitterroot | Upper | Near Darby (12344000) | 454 | Low / Good Morning Shape |
| Bitterroot | Middle | Bell Crossing nr Victor (12350250) | 280 | Low / Technical |
| Bitterroot | Lower | Near Missoula (12352500) | 675 | Low / Watch Temps Early Week |
| Blackfoot | Lower | Near Bonner (12340000) | 613 | Low / Float Closure Below Weigh Station |
| Clark Fork | Upper | Above Missoula (12340500) | 1,110 | Low / Fall Transition |
| Clark Fork | Lower | Below Missoula (12353000) | 1,780 | Low / Morning and Cloud Windows |
| Rock Creek | Lower | Near Clinton (12334510) | 255 | Clear / Excellent Wade Shape |
| West Fork Bitterroot | Lower | Near Conner (12342500) | 354 | Managed / Strong Smaller-Water Option |
Flows remain low, but cooler weather should make these levels much easier to work with. The biggest improvement this week is not additional water; it is cooler air, cooler nights, more cloud cover, and the beginning of the fall hatch transition.
Fly Box of the Week
Dry Flies
- Trico spinner, size 18–22
- Hecuba / Fall Drake, size 10–12
- Mahogany Dun, size 14–16
- BWO dry or emerger, size 18–22
- Hopper, size 8–12
- Ant and beetle, size 12–18
- Caddis dry, size 14–18
Nymphs
- Hecuba nymph or Pheasant Tail, size 10–14
- BWO nymph, size 18–20
- Caddis pupa, size 14–18
- Perdigon, size 14–18
- Frenchie, size 14–18
- Duracell or small jig attractor, size 14–18
Streamers
- Olive streamer, size 4–8
- Black streamer, size 4–8
- Tan or natural sculpin, size 4–8
- White streamer, size 4–8
Hatch and Fly Chart – Early September Edition
| Hatch / Insect | Activity | Best Time | Recommended Fly | Size |
|---|---|---|---|---|
| Tricos | Still one of the most reliable morning hatches | Early morning | Spinner or small mayfly pattern | 18–22 |
| Terrestrials | Hoppers, ants, and beetles remain major food sources | Mid-morning through afternoon | Hopper, ant, beetle, or foam attractor | 8–18 |
| Hecubas | Increasingly important with cooler, cloudy weather | Late morning through afternoon | Hecuba, Brindlechute, rusty mayfly, or large cripple | 10–12 |
| Mahogany Duns | Beginning the fall transition | Late morning through afternoon | Mahogany dry, cripple, or emerger | 14–16 |
| BWOs | Best during cloudy, cool, or showery periods | Late morning through afternoon | BWO dry, emerger, or nymph | 18–22 |
| Caddis | Still present, with Blackfoot October Caddis becoming worth watching | Morning and evening | Dry, pupa, soft hackle, or caddis attractor | 12–18 |
The hatch menu is changing. Tricos and terrestrials still connect late summer to early fall, but Hecubas, Mahoganies, and BWOs should become increasingly important as September weather arrives. Wednesday and Friday are the days to watch closely.
Gear Picks of the Week
Long Leaders and Fine Tippet
Tricos and low, clear water still demand good presentations. Carry 4X, 5X, and 6X and be prepared to lengthen leaders when targeting individual rising fish.
Rain Shell
Wednesday and Friday bring the first meaningful cool, wet fishing weather in a while. A lightweight shell may buy you one of the better dry-fly or streamer windows of the week.
Fall Mayfly Box
Hecubas, Mahogany Duns, BWOs, and Tricos should now have a permanent place in the boat or pack alongside the terrestrial box.
Strategy and Expectations This Week
This is the first week in a while where we are not automatically recommending that everyone be done before lunch every single day. Monday and Tuesday remain warm and should still be treated as morning-first days. Wednesday through Friday are different.
Cooler temperatures, clouds, and showers could bring Hecubas, Mahoganies, and BWOs into play later in the day while also improving streamer fishing. The Clark Fork may benefit the most from the weather shift, while the Bitterroot remains the best overall combination of access, dry-fly opportunities, and fishing styles. Rock Creek is the best wade-fishing option, and the West Fork remains an excellent smaller-water choice.
