Western Montana Fly Fishing Report
Current Restrictions and Closure Summary
Montana FWP currently lists no hoot-owl restrictions on our core western Montana rivers.
- 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.
- Rock Creek: Fishing from boats or vessels is prohibited July 1 through November 30. Plan on wade fishing only.
- Bitterroot, Clark Fork, and West Fork: No current emergency angling closures affecting our standard fishing areas were listed when this report was prepared.
- Daily reminder: Check Montana FWP before every trip because emergency closures can change.
Regional River Conditions Overview
The region has settled into a stable September pattern. Flows have dropped from the early-month rain bump, but the Bitterroot, Blackfoot, Clark Fork, and Rock Creek remain in considerably better shape than they were during the lowest part of August.
The fishing schedule has also changed. There is little reason to rush to the river at daylight. Cooler overnight temperatures are delaying insect activity, and the better fishing is generally developing from mid-morning through the afternoon.
Sunday through Thursday look relatively warm, dry, and bright. That should favor careful dry-fly presentations, terrestrials, and dry-dropper rigs. Friday cools somewhat, and Saturday is cooler again. Those cooler late-week conditions could improve BWOs, Mahoganies, and streamer fishing.
Bitterroot River
Conditions
The Bitterroot is clear, stable, and in good early-fall condition. Recent verified readings put the upper river near Darby around 454 CFS and the lower river near Missoula around 1,020 CFS. The river has dropped substantially from the early-September rain bump but remains healthier than the late-August low-water period.
The hatch transition is now obvious. Terrestrials are still very much worth fishing, but October Caddis are showing, BWOs are increasingly important during clouds, and Mahogany Duns and Hecubas are becoming legitimate fall targets.
Where to Fish
- Riffle edges transitioning into deeper green water
- Tailouts and slicks where fish are rising
- Foam lines and inside seams
- Grassy banks, brush, and undercuts for terrestrials
- Side channels with depth and current
- Deeper shelves and banks for streamers
How to Fish It
- Slow down and watch slick water before casting
- Fish a single dry when trout are actively feeding on the surface
- Use hoppers, ants, and beetles to prospect banks through the warmer part of the day
- Run Frenchies, Perdigons, Pheasant Tails, or caddis pupa below a terrestrial
- Carry October Caddis adults and pupa
- Watch for BWOs during clouds and cooler periods
- Carry Mahogany Duns and Hecubas as the fall hatch develops
- Streamer fish banks, shelves, and deeper seams when light conditions soften
Top Patterns
- Hopper, size 8–12
- Ant, size 12–18
- Beetle, size 12–16
- BWO dry or emerger, size 18–22
- Mahogany Dun, size 14–16
- Hecuba / Fall Drake, size 10–12
- October Caddis adult or pupa, size 8–12
- Small olive, black, or tan streamer
Blackfoot River
Conditions
The Blackfoot near Bonner is around 705 CFS on the latest verified reading. The river has settled into a stable September rhythm with cool water, clear conditions, and good early-fall holding water.
Terrestrials remain productive around willows, banks, and boulder water, but October Caddis, BWOs, Mahoganies, Hecubas, and streamers are becoming increasingly important.
Where to Fish
- Willow-lined banks
- Boulder pockets and current breaks
- Riffle edges
- Deeper buckets
- Soft inside seams
- Shaded shelves below heavier current
How to Fish It
- Prospect hoppers and foam attractors around banks and boulders
- Use smaller ants and beetles in soft bank water
- Drop a Frenchie, Perdigon, Pheasant Tail, or caddis pupa below the dry
- Carry October Caddis adults and pupa
- Watch for BWOs during gray or cool conditions
- Streamer fish boulder edges, buckets, and banks
- Plan all floats around the active Weigh Station closure
Top Patterns
- Hopper, size 8–12
- Ant or beetle, size 12–18
- October Caddis adult or pupa, size 8–12
- BWO, size 18–22
- Mahogany Dun, size 14–16
- Hecuba, size 10–12
- Zirdle or Rubber Legs, size 8–10
- Olive, black, tan, or white streamer
Clark Fork River
Conditions
The Clark Fork above Missoula is around 1,410 CFS on the latest verified reading, with the lower river around 2,390 CFS. The river has settled after the September rain bump and remains in good early-fall shape.
This remains one of the better choices for patient dry-fly anglers. Fish are using riffle edges, inside seams, tailouts, side channels, and deeper green lanes. Watching before casting matters more than covering miles of water.
Where to Fish
- Riffle edges and foam lines
- Long inside seams
- Tailouts and slicks
- Grassy islands and soft banks
- Side-channel seams
- Deeper green lanes and shelves
How to Fish It
- Watch for feeding fish before casting into slick water
- Use hoppers, ants, and beetles along grassy banks and islands
- Carry BWOs for clouds, drizzle, or cooler afternoons
- Fish Mahogany Duns and Hecubas as those hatches become more established
- Carry October Caddis adults and pupa
- Nymph Frenchies, Perdigons, Pheasant Tails, and caddis pupa through riffle edges
- Streamer fish banks and soft inside seams when light conditions improve
Top Patterns
- Hopper, size 8–12
- Ant or beetle, size 12–18
- BWO dry or emerger, size 18–22
- Mahogany Dun, size 14–16
- Hecuba, size 10–12
- October Caddis, size 8–12
- Frenchie or Perdigon, size 14–20
- Small to medium streamer
Rock Creek
Conditions
Rock Creek is around 292 CFS near Clinton on the latest verified reporting. The creek is clear, cool, and in good wade-fishing shape. Flows have dropped from the larger September rain bump but remain healthier than they were during the lowest part of August.
Rock Creek is now a full fall-transition fishery. Terrestrials remain useful, but BWOs, October Caddis, Mahogany Duns, Hecubas, and streamers should receive more attention each week.
Where to Fish
- Pocket water
- Boulder edges
- Riffle drops
- Plunge pools
- Shaded and undercut banks
- Soft seams behind heavier water
How to Fish It
- Prospect terrestrials through pocket water and along banks
- Use Frenchies, Perdigons, Pheasant Tails, and caddis pupa as droppers
- Carry October Caddis adults and pupa
- Watch for BWOs during cooler conditions
- Keep Mahogany Duns and Hecubas available
- Streamer fish deeper pockets, plunge pools, and undercuts
- Move slowly and fish good water before stepping into it
Top Patterns
- Hopper, ant, or beetle, size 8–18
- BWO, size 18–22
- October Caddis, size 8–12
- Mahogany Dun, size 14–16
- Hecuba, size 10–12
- Frenchie or Perdigon, size 14–20
- Small olive or black streamer
West Fork of the Bitterroot
Conditions
The most recent verified West Fork gauge reading available when this report was prepared was around 322 CFS near Conner. Managed flows continue to keep the West Fork in strong smaller-water shape for September.
This remains an excellent choice for anglers who prefer technical water, lighter tackle, dry-droppers, and careful presentations.
Where to Fish
- Riffle edges and pocket water
- Protected tailouts
- Inside seams
- Foam lines beside structure
- Deeper pockets below wood and boulders
- Overhanging grass and shaded banks
How to Fish It
- Use longer leaders in softer water
- Prospect ants, beetles, and small hoppers around banks
- Carry Hecubas and Mahogany Duns
- Fish October Caddis pupa below an attractor
- Use Perdigons, Pheasant Tails, and Frenchies below a dry
- Try small olive or bright streamers through deeper pockets
- Make the first cast count before wading into productive water
Top Patterns
- Hecuba, size 10–12
- Mahogany Dun, size 14–16
- October Caddis, size 8–12
- Hopper, ant, or beetle, size 10–18
- BWO, size 18–22
- Perdigon or Pheasant Tail, size 14–18
- Small olive streamer
Planning Note
Sunday through Thursday: Expect relatively warm, mostly bright conditions. There is no reason to start at daylight. Let the water warm, watch for surface activity, and plan on terrestrials and dry-droppers through the brightest part of the day.
Friday: Cooler weather and additional cloud cover should improve fall mayfly potential. Keep BWOs, Mahoganies, and streamers ready.
Saturday: The coolest day of the week. A cold morning may delay fishing, but this could become one of the more interesting fall-hatch days once the water warms. Do not be surprised if the better fishing happens late morning through afternoon.
The overall strategy this week is simple: start later, watch the water, fish terrestrials while the sun is out, and switch toward fall mayflies and streamers when the light softens.
River Flow Snapshot – September 20, 2026
Gauge reporting has been inconsistent on several USGS stations this month. The values below are the latest numerical readings that could be independently verified when this report was prepared. Dates vary by gauge, and USGS values are provisional.
| River | Section | Gauge | Latest Verified Flow | Status |
|---|---|---|---|---|
| Bitterroot | Upper | Near Darby (12344000) | 454 CFS | Clear / Good Fall Shape |
| Bitterroot | Middle | Bell Crossing nr Victor (12350250) | 489 CFS | Latest Verified Gauge Reading |
| Bitterroot | Lower | Near Missoula (12352500) | 1,020 CFS | Healthy September Flow |
| Blackfoot | Lower | Near Bonner (12340000) | 705 CFS | Good Fall Flow / Float Closure Below Weigh Station |
| Clark Fork | Upper | Above Missoula (12340500) | 1,410 CFS | Settling / Good Early-Fall Flow |
| Clark Fork | Lower | Below Missoula (12353000) | 2,390 CFS | Healthy September Flow |
| Rock Creek | Lower | Near Clinton (12334510) | 292 CFS | Clear / Wade Fishing Only |
| West Fork Bitterroot | Lower | Near Conner (12342500) | 322 CFS | Managed / Strong Smaller-Water Option |
The rivers have largely settled after the early-September rain bump. Flows are lower than two weeks ago but remain in considerably better shape than they were during late August.
Fly Box of the Week
Dry Flies
- Hopper, size 8–12
- Ant, size 12–18
- Beetle, size 12–16
- BWO dry / emerger, size 18–22
- Mahogany Dun, size 14–16
- Hecuba / Fall Drake, size 10–12
- October Caddis, size 8–12
Nymphs
- Frenchie, size 14–18
- Perdigon, size 14–20
- Pheasant Tail, size 14–20
- BWO nymph, size 18–22
- Caddis pupa, size 12–18
- October Caddis pupa, size 8–12
- Jigged Hare’s Ear, size 14–18
Streamers
- Thin Mint
- Sculpzilla
- Woolly Bugger
- Sparkle Minnow
- Mini Dungeon
- Small olive sculpin
- Black or tan streamer
Hatch and Fly Chart – Late September Edition
| Hatch / Insect | Activity | Best Time | Recommended Fly | Size |
|---|---|---|---|---|
| Terrestrials | Still productive, especially hoppers, ants, and beetles | Late morning through afternoon | Hopper, ant, beetle, or foam attractor | 8–18 |
| BWOs | Increasingly important during clouds and cooler weather | Late morning through afternoon | BWO dry, emerger, or nymph | 18–22 |
| Mahogany Duns | Fall hatch is building | Late morning through afternoon | Mahogany dry, cripple, or emerger | 14–16 |
| Hecubas | Becoming increasingly important | Late morning through afternoon | Hecuba, Brindlechute, or rusty mayfly | 10–12 |
| October Caddis | Adults are showing and activity should continue building | Late morning, afternoon, and evening | October Caddis adult or pupa | 8–12 |
| Smaller Caddis | Still present around riffles and softer edges | Variable | Elk Hair Caddis, X-Caddis, pupa, or soft hackle | 14–18 |
This is now a true fall hatch menu. Terrestrials remain productive enough that the hopper box should stay in the boat, but BWOs, Mahogany Duns, Hecubas, and October Caddis should receive increasing attention every week.
Gear Picks of the Week
Fall Dry-Fly Box
BWOs, Mahogany Duns, Hecubas, October Caddis, ants, beetles, and remaining hopper patterns should now make up the core dry-fly selection.
4X–6X Tippet
Clear September water still rewards careful presentations. Keep lighter tippet available for selective fish in slicks and tailouts.
Streamer Box
Streamer fishing will continue getting better as fall progresses. Carry olive, black, tan, and lighter baitfish patterns so you can adjust to light and water clarity.
Strategy and Expectations This Week
The Bitterroot remains the best overall local choice. It provides the widest mix of terrestrials, dry-droppers, October Caddis, fall mayflies, and streamer opportunities.
The Clark Fork is the best river for anglers willing to slow down and hunt individual fish. Watch slicks and tailouts before casting, and be prepared to switch between terrestrials, fall mayflies, and nymphs.
Rock Creek remains the best wade-fishing choice. Expect clear water, pocket fishing, terrestrials, fall mayflies, and small streamers.
The Blackfoot is increasingly becoming a fall fishery. October Caddis and streamers deserve more attention, but the Weigh Station floating closure remains the major logistical consideration.
The West Fork remains the dependable smaller-water option. Managed flow, cooler temperatures, and technical water make it a strong choice for anglers who prefer lighter tackle and careful presentations.
