Southwest Montana, Montana
Beaverhead River Fishing Report: May 20, 2026
Beaverhead River is good today with 521 cfs at the primary gauge and late afternoon into evening as the best window.
- Status
- good
- Flow trend
- falling
- Best window
- Late afternoon into evening
- Best methods
- nymphs, dry flies
Quick Summary
Beaverhead River is in a useful fishing window today. USGS showed 521 cfs and 1.71 feet at 7:15 AM, with the flow trend falling. Water temperature was Not reported by the gauge. Start with nymphs, then adjust to dry flies if fish show you a better lane or feeding level.
Conditions Snapshot
| Field | Value |
|---|---|
| Status | Good |
| Flow | 521 cfs at 7:15 AM |
| Gauge Height | 1.71 feet |
| Water Temp | Not reported |
| Clarity | Not reported |
| Trend | Falling |
| Best Window | Late afternoon into evening |
| Best Method | nymphs; dry flies |
| Wadeability | Good |
Weather
For Dillon, MT, the National Weather Service forecast says: Today: A slight chance of rain between 9am and 10am. Partly sunny, with a high near 62. West southwest wind 3 to 12 mph, with gusts as high as 20 mph. Chance of precipitation is 20%. No active NWS alerts were returned for the point check. Plan around wind, changing light, and any showers or storms rather than assuming a full-day dry fly window.
River Notes
The best starting point is water that matches the current gauge: inside seams, protected banks, riffle drop-offs, and slower buckets rather than the heaviest current. A falling trend is worth watching through the day; if the hydrograph turns sharply upward, clarity and wade safety can change before hatch timing does. Clarity was not available from an official gauge during this check, so treat it as Not reported and verify it at the access before committing to a long float or wade plan.
Hatch Activity
Current hatch guidance is based on seasonal May patterns for this river system, current public report context where available, and today’s official gauge/weather check.
| Hatch | Size | Notes |
|---|---|---|
| Blue Winged Olive | 18-22 | Small dries in slower seams |
| Midge | 18-24 | Tailwater staple |
| Caddis | 14-18 | Check riffles and edges |
| Scuds/Sowbugs | 14-18 | Productive tailwater food |
Recommended Flies
| Category | Fly | Size | Notes |
|---|---|---|---|
| Nymph | Sowbug | 14-18 | Tailwater nymph |
| Nymph | Zebra Midge | 18-22 | Use under an indicator |
| Nymph | Pheasant Tail | 16-20 | Small mayfly nymph |
| Dry | BWO Comparadun | 18-22 | For visible risers |
| Dry | Griffith’s Gnat | 18-22 | Midge clusters |
Tactics
Start with nymphs in defined lanes and adjust weight, depth, or leader length before changing flies. If fish begin rising, simplify to a single dry or dry with an emerger/dropper and lengthen the leader. In bright or windy periods, return to subsurface presentations along protected banks and broken water. Re-check the gauge before wading new crossings, especially if the trend changes from stable or falling to rising.
Gauge Links
| Gauge | Flow | Temp | Link |
|---|---|---|---|
| BEAVERHEAD RIVER AT BARRETTS MT | 521 cfs | Not reported | USGS 06016000 |
Sources
Official sources checked: USGS station 06016000 and the National Weather Service forecast for the Dillon, MT area. This report is an original Custom FlyBox summary based on current official gauge and weather data, with local public conditions reports reviewed separately for hatch, access, and method context.