7-day U.S. Geological Survey chart
Recent flow
Discharge
1,880 cfs1,440 cfs
Sep 5Sep 11
Latest reading: 1,840 cfs. Stable over about 6 hours. Chart covers Sep 5 through Sep 11; readings are provisional and may be revised.
All Montana reports
Bighorn River Fishing Report — Montana
Photo: NASA Opens in a new tab. · Public domain
Should I go fishing?
Check the water temperature first.
Water temperature is unconfirmed. Use a stream thermometer; stop trout fishing at 70°F or warmer, or sooner if fish show stress.
Fishing rating78
Rating updatedRiver local time:
Why this recommendation?
USGS shows 1,840 cfs. The flow has been stable over about 6 hours. USGS marks this reading provisional and may revise it. USGS records for this date (1935-2025, 91 readings) show a median near 2,460 cfs and the lower quartile near 1,980 cfs; today's flow is below normal for the date. This is below normal, so edge depth, temperature, and pressure matter.
Available live dataHighHow much of the live flow, weather, and alert data came back.
Confidence in this recommendationMediumWater temperature not verified; do not use this score to clear warm-water risk.
Usually checks again about every 45 minutes
If you go
- Check first
- Use USGS 06287000 below Yellowtail Afterbay as the flow source for this page.
- Try
- Use the Afterbay flow to decide whether to wade or plan a boat day.
- Leave when
- Skip or narrow the plan when launches, take-outs, shuttle timing, land status, or weather make the area uncertain, or when flow changes make wading unsafe.
Flow and weather
Showing server-checked river conditions while current readings refresh.
- Flow
- 1,840 cfs
- Stable over about 6 hoursU.S. Geological Survey may revise this reading
- Air forecast
- 51°F
- Next 24h high
- 71.0°F
NWS air forecast near
- Rain chance
- 29%
This is an air forecast, not a river-temperature reading. Check the water with a stream thermometer before fishing in hot weather.
Latest stored weather check
Chance Rain Showers
- Wind
- 3 mph
- Weather checked
More forecast and source details
Chance Rain Showers
National Weather Service
Bighorn River near Fort Smith
The National Weather Service forecast is temporarily unavailable.
Live data
Where these readings come from
Current U.S. Geological Survey gauge: Bighorn River below Yellowtail Afterbay
Stable over about 6 hoursU.S. Geological Survey may revise this readingObserved
Flies for this time of year
Seasonal starting points, not a live hatch report. Match what you see on the water.
- Blue-Winged Olive Patternssmall BWOView fly guide ↗
- X-CaddisView fly guide ↗
- Trout Streamer PatternsstreamerView fly guide ↗
See flies for every season
SeasonWhat to look forFlies to try
Winter to early spring
What to look forMidges, scuds, sowbugs, eggs where legal, and slow tailwater nymphs
Flies to try
Also try scud, sowbug, Ray Charles
May to July
What to look forPMDs, caddis, midges, yellow sallies, worms during bumps
August to OctoberThis season
What to look forTricos, pseudos, caddis, hoppers, small baitfish
Flies to try
Also try Trico spinner, hopper-dropper
Late fall
What to look forMidges, small olives, scuds, sowbugs, streamer windows
Flies to try
Each fly name opens its matching Fly Box guide.
More fishing tips
Methods, fish species and trip notes
How to fish Bighorn River today.
Stable releases and moderate weather make the Bighorn one of the more reliable trout plans in Montana. The tradeoff is pressure, technical fish, boat traffic, and access that rewards preparation.
Stable tailwater flow
Nymph riffles, seams, and flats with scuds, sowbugs, midges, or PMDs.
Higher release
Fish edges, softer seams, and boat-based drifts. Avoid unsafe wading.
Low clear flow
Use smaller flies, longer leaders, and careful presentations to pressured fish.
Wind or clouds
Streamers, soft hackles, and leeward banks can become more useful.
Wading, bank fishing or floating?
Access choicesNo single best option
Wading, Bank fishing, and Floating have the same top score. Use current access, footing, weather, and local rules to choose.
Wading78/100
Wading is in play only where your chosen access has clear footing, legal entry, and no forced crossings.
Bank fishing78/100
Bank and edge fishing remains a practical low-commitment option if access is legal and footing is safe.
Floating78/100
A float is in play where this report supports boat access and wind, releases, and shuttle logistics are manageable.
Full river report
Is Bighorn River worth the trip today? Check flow, weather, hatches, access, and rules for Montana before you go.
The Montana Bighorn below Yellowtail Afterbay is a famous trout tailwater, but access, releases, reservation context, and exact rules matter. Use the Afterbay gauge and official sources before fishing.
Fishing words used on this page
- U.S. Geological Survey (USGS) gauge
- A USGS gauge is an official river station that measures flow or water height.
- Cubic feet per second (cfs)
- Cubic feet per second, or cfs, shows how much water passes the gauge each second.
- Technical fishing
- Technical fishing means the fish are hard to fool, so careful casts and natural drifts matter.
- Nymph
- A nymph is a young water insect. Anglers also use the word for a fly that copies it.
- Presentation
- Presentation means how you cast and move the fly so it looks natural to a fish.
- Riffle
- A riffle is shallow, fast water broken by rocks.
- Seam
- A seam is the line where fast and slow water meet.
- Attractor fly
- An attractor fly is bright or bold. It draws a strike without copying one exact insect.
- Blue-winged olive (BWO)
- Blue-winged olives, or BWOs, are small mayflies that often hatch in cool or cloudy weather.
- Caddis
- Caddis are small water insects. The adults look a little like tiny moths.
Why this call
Why this score
FlowUse caution
USGS shows 1,840 cfs. The flow has been stable over about 6 hours. USGS marks this reading provisional and may revise it. USGS records for this date (1935-2025, 91 readings) show a median near 2,460 cfs and the lower quartile near 1,980 cfs; today's flow is below normal for the date. This is below normal, so edge depth, temperature, and pressure matter.
SeasonHelps
Fall: BWOs, midges, streamers, and cooling-water brown trout behavior.
WeatherHelps
The current NWS air forecast is about 51F, and the next 24-hour high reaches about 71F. Chance Rain Showers.
Public alertsHelps
No active NWS alert was returned for this forecast point.
Fishing usefulnessHelps
Skip or narrow the plan when launches, take-outs, shuttle timing, land status, or weather make the corridor uncertain, or when flow changes make wading unsafe.
Trip notes
Check these before you choose a reach.
Use USGS 06287000 below Yellowtail Afterbay for the current release trend. Moderate stable releases support technical nymph and dry-fly work. Higher releases move the plan toward boat-based drifts and safer edges.
Skip or narrow the plan when launches, take-outs, shuttle timing, land status, or weather make the area uncertain, or when flow changes make wading unsafe.
Start with the Afterbay flow and the legal access plan. Then decide whether the day is a nymphing float, a technical dry-fly hunt, or a streamer window around wind, clouds, and bank structure.
If the Bighorn is too crowded, windy, or logistically tight, compare the Big Hole for freestone fishing, the Bitterroot for western Montana hatches, or the Madison for another major Montana trout plan.
Bighorn River access and rules.
Use these places as starting points. Open the access link below and check posted signs before you park or enter.
Before you go
Montana FWP rules, NPS Bighorn Canyon information, and Crow Reservation land/access context should be checked before fishing or leaving public access.
Where to access the river
Afterbay access
Core upper tailwater launch and flow-reference area below Yellowtail Afterbay.
Three Mile area
Important public-access style area. Confirm current site rules before launching.
Bighorn FAS
FWP access context for lower Fort Smith-area planning.
- Limited access concentrates anglers and boats. Plan shuttle, launch timing, and etiquette before arrival.
- Land status around the river is complex. Stay within legal access and confirm reservation-related rules before leaving the river area.
- Tailwater ledges can be slick and deceptively deep. Do not wade just because the flow looks steady.
Sources and report details
Official agencies and primary river operators come first. Secondary tools are labeled so you know what carries the most weight.
Rules and closures
Check what is allowed, where the rule applies, and whether the river is open.
Flow and weather
Check the latest river reading and forecast before you leave.
Access and land
Check public entry points, land rules, and seasonal access changes.
See all 6 checked sources
Rules and closures
Check what is allowed, where the rule applies, and whether the river is open.
What this source covers
Open the current rules and check the river section, season, and special limits.
Flow and weather
Check the latest river reading and forecast before you leave.
What this source covers
Open this page and check the latest safety advice before your trip.
What this source covers
Open this page for more river information and check when it was last updated.
What this source covers
Open this river reading to check the latest level, flow, and update time.
Access and land
Check public entry points, land rules, and seasonal access changes.
What this source covers
Open the land or access page, then check signs before you park or enter.
What this source covers
Open the land or access page, then check signs before you park or enter.
How this report was checked
How this report was checked
Reviewed byBlueStreamFly River Review Team
Trip guidance checked
What was checked: This Bighorn River report is maintained from USGS Yellowtail Afterbay flow data, National Park Service Bighorn River access and flow background, Montana FWP fishing regulations, FishMT access records, weather, media-credit, and tailwater planning sources.
Live measurements and forecasts keep their provider timestamps. Rules, access, and trip guidance use the source-review date shown here. BlueStreamFly planning advice is editorial interpretation, not an agency notice.
First-hand experience: BlueStreamFly does not claim a first-hand visit or local field test for this report unless a real contributor is explicitly named and linked.
Quick questions
What should I check first before fishing the Montana Bighorn River?
Check Afterbay flow, Montana rules, NPS/FWP access, land status, weather, and shuttle logistics.
Are there special fishing rules on the Montana Bighorn River?
Yes. Montana rules apply, and land/access context near Crow Reservation lands must be handled carefully.
Is the Montana Bighorn River a good fly-fishing river?
Yes, if you match the reach, season, target species, water temperature, and current access rules. This report is built to help you choose that plan.
What flies should I bring for the Montana Bighorn River?
Bring the hatch-chart flies, confidence nymphs, and a backup streamer or warmwater box so you can adjust to flow, clarity, and temperature.
How should I plan access for the Montana Bighorn River?
Use official launches and access areas such as Afterbay, Three Mile, and Bighorn FAS style planning points.