Fly Fishing the Bighorn River

The Bighorn flows out of Yellowtail Dam on the Crow Reservation in south-central Montana, with the legendary first 13 miles below the Afterbay Dam (from Three Mile down to Bighorn Access) holding some of the densest trout populations in the country. Cold, nutrient-rich tailwater flows grow heavy brown and rainbow trout that feed steadily through prolific aquatic insect emergences. Most anglers fish from drift boats with frequent wade-out spots on the long gravel flats. It is best known for its blanket Trico and Baetis hatches and reliable year-round midge fishing.

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When to fish

Year-round

Best months: year-round

Best

Midge: year-round, prime Dec–Mar. Blue-winged Olive / Baetis: Mar–May, Sep–Oct.

Today's conditions

Where to fish

Along the Bighorn River

The famous first 13 miles below Yellowtail Dam are reached via the Afterbay, Three Mile, and Bighorn access points; most fishing is done by drift boat with wade-out spots.

The water

Tailwater

Key hatches

Midge
Blue-Winged Olive
Pale Morning Dun
Yellow Sally
Caddisfly

Hatch calendar

Conditions

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6-day forecast

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Forecast from the National Weather Service ↗

Hatch calendar

Months each hatch is active on the Bighorn River, with hook sizes and local timing notes.
Hatch · hook	J	F	M	A	M	J	J	A	S	O	N	D
Midge(midges)hook #18–20year-round, prime Dec–Mar	January	February	March	April	May	June	July	August	September	October	November	December
Blue-winged Olive(mayflies)hook #16–20Mar–May, Sep–Oct				April	May	June			September	October	November
Pale Morning Dun(mayflies)hook #16–18Jun–Jul							July	August
Yellow Sally(stoneflies)hook #16–18Jun–Jul							July	August
Caddisfly(caddis)hook #16–18								August	September
Trico(mayflies)hook #18–20Aug–Sep, mornings								August	September