Fly fishing report · West

Bighorn River

A Bighorn River report for Montana tailwater anglers checking Afterbay flow, hatches, access points, public-use rules, weather, and sources.

Check flow & weather

Today's river scoreHigh source confidence

Poor

Best option: Float.

A float can fit better than wading only if launches, shuttle, boat skill, wind, and local rules all check out.

Updated Jul 13, 11:25 PM UTCUsually refreshes about every 45 minutes

Recommended approachFloat

Mode scores adjust the river-wide score for the risks of wading, bank fishing, or floating.

Wade15/100

Wading is the most sensitive plan today. Use protected edges only, avoid crossings, and downgrade quickly if clarity or current feels wrong.

Bank / edge27/100

Bank and edge fishing is the safer default when water is high, pushy, or not fully verified.

Float · Best fit39/100

A float can fit better than wading only if launches, shuttle, boat skill, wind, and local rules all check out.

Confirm before you leave

Flow and weather right now.

Use the flow trend to confirm the score before you leave. Weather can change the safest and most productive fishing window.

River strategy

A technical tailwater with limited access.

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.

Use USGS 06287000 below Yellowtail Afterbay as the flow source for this page.
Plan around limited public access such as Afterbay, Three Mile, and Bighorn FAS style launches.
Midges, scuds, sowbugs, PMDs, caddis, tricos, and small streamers all belong in the box.
Stay careful with land status and Montana/Crow Reservation context when leaving the river corridor.

Why this score moved

HeatLowers score

The NWS forecast is near 97F. Without live water temperature, heat risk needs a conservative check.

Best mode nowLowers score

Float: A float can fit better than wading only if launches, shuttle, boat skill, wind, and local rules all check out.

FlowUse caution

USGS shows 1,500 cfs with a stable over about 6 hours trend. same-date USGS history (1935-2025, 91 readings) puts normal around 4,650 cfs and the low-water marker near 2,020 cfs; today's flow is unusually low for the date. Low water can make fish spooky, warm, pressured, or concentrated; check temperature and handling risk.

Target choiceUse caution

Coldwater targets are a poor choice in this heat window without a current water-temperature check; consider warmwater targets only where that matches the river and rules.

Public alertUse caution

A heat alert is active near this forecast point, so the score is capped until water temperature and fish-handling risk are checked. NWS alert: Extreme Heat Warning issued July 13 at 1:08PM MDT until July 15 at 12:00AM MDT by NWS Billings MT.

Read the water

What changes the plan.

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.

Field plan

Fish it with intention.

Best flows

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.

When to skip

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.

Local plan

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.

Backup water

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.

Hatches & flies

Bring a flexible box.

TimingWhat to watchUseful flies

Winter to early springMidges, scuds, sowbugs, eggs where legal, and slow tailwater nymphsZebra midge, scud, sowbug, Ray Charles, small leech

Reviewed pattern · report says “Zebra midge”Zebra MidgeLook for a very slim tapered thread body, evenly spaced contrasting wire rib, a small bead, and no tail or wing. The reviewed classic is black with silver wire and a silver bead. Red, olive, brown, glass-bead, jig-hook, resin-coated, or tailed forms must remain labeled variations rather than replacing the classic identity.See photos & how to fish it

Reviewed family · report says “scud”Scud Fly PatternsScud patterns typically use a curved hook, tapered dubbed body, shellback, rib segmentation, antennae, and brushed legs. Olive, tan, gray, orange, weighted, bead-body, and pregnant forms remain labeled—not aliases for one recipe.See family guide + 3 more reviewed guides in the Fly Box

May to JulyPMDs, caddis, midges, yellow sallies, worms during bumpsPMD emerger, sparkle caddis, midge pupa, San Juan worm, soft hackle

Reviewed family · report says “PMD emerger”Pale Morning Dun PatternsPMD names an insect group, not one fly. Pale nymphs, trailing-shuck emergers, upright or low-riding duns, cripples, and spent-wing spinners stay visibly separate.See family guide

Reviewed family · report says “sparkle caddis”Caddis Patterns by StageCaddis is not one fly. Larvae live below, pupae and emergers rise through the column, tent-wing adults ride or move on top, and spent forms create other silhouettes.See family guide + 3 more reviewed guides in the Fly Box

August to OctoberTricos, pseudos, caddis, hoppers, small baitfishTrico spinner, small BWO, X-caddis, hopper-dropper, streamer

Reviewed pattern · report says “Trico spinner”Trico SpinnerThe reviewed dry form is extremely sparse and flat, using a black body or thread head and pale spent wing. A weighted Sunken Trico Spinner is a separate variant.See photos & how to fish it

Reviewed family · report says “small BWO”Blue-Winged Olive PatternsBWO describes a hatch group, not one fly. Nymph, emerger, dry, cripple, and spinner profiles must stay separate because they occupy different parts of the water column.See family guide + 2 more reviewed guides in the Fly Box

Late fallMidges, small olives, scuds, sowbugs, streamer windowsMidge, BWO emerger, scud, sowbug, black leech

Reviewed family · report says “Midge”Midge Patterns by StageMidge wording can mean a threadlike larva, wing-padded pupa, film emerger, tiny adult, or visible cluster. Those profiles fish at different depths.See family guide

Reviewed family · report says “BWO emerger”Blue-Winged Olive PatternsBWO describes a hatch group, not one fly. Nymph, emerger, dry, cripple, and spinner profiles must stay separate because they occupy different parts of the water column.See family guide + 3 more reviewed guides in the Fly Box

Use the Afterbay flow to decide whether to wade or plan a boat day.

Start with scuds, sowbugs, and midges before forcing larger attractor flies.

Watch flats and foam lines for pods before changing every fly in the box.

Use streamers during clouds, wind, or flow changes, especially along banks and buckets.

Respect access limits and do not assume every bank or island is available for public use.

Access & responsibility

Know the entry. Know the exit.

Montana FWP rules, NPS Bighorn Canyon information, and Crow Reservation land/access context should be checked before fishing or leaving public access.

Afterbay access

Core upper tailwater launch and flow-reference area below Yellowtail Afterbay.

Three Mile area

Important public-access style corridor; confirm current site rules before launching.

Bighorn FAS

FWP access context for lower Fort Smith-area planning.

Transparent sources

Check the facts behind the plan.

Last material review: 2026-05-31

flowUSGS Bighorn River below Yellowtail Afterbay 06287000 accessNPS Bighorn River in Montana backgroundNPS Bighorn River flow background regulationMontana FWP fishing regulations accessBighorn fishing access site safetyNational Weather Service forecast point

Common questions

Before you leave.

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 regulations 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.