by Huston Heatherly

The Bighorn river in Montana below the Yellowtail Dam offers 30 miles of pristine trout fly fishing. Our guide will help you prepare for an amazing fly fishing trip to Montana.

Bighorn River Location

While the Bighorn river passes through parts of both Wyoming and Montana, the more renowned fly fishing occurs on stretches of the river in south-central Montana.

The closest airport is located in Billings, MT (BIL) while Ft. Smith has a local airport that can accommodate private planes. Both sites offer excellent culture and lodging for anglers looking to make a trip out of it.

About the Bighorn River

The Bighorn River, in its entirety, is 461 miles in length and is a tributary of the Yellowstone River.

The most fished portion of the river is located in Montana below the Yellowtail Dam and offers 30 miles of pristine trout fishing.

Further down from the Yellowtail Dam is the Afterbay Dam which keeps the water at a level flow and helps to maintain a nearly constant water temperature making it an ideal trout fishery year round.

Regarding river characteristics, the stretch of the Bighorn beneath Yellowtail features rock and gravel bottom with mostly deeper, consistent, currents with few riffles making it more of a floating river.

Types of Fish

The Bighorn river is renowned for its large brown trout that are consistently taken from the river. The river also contains rainbow trout, though this species can be a little scarcer when compared to the brown population.

The Bighorn is not only known as a blue ribbon trout fishery but when compared to other rivers the fish population is astounding.

Current counts have the Bighorn holding nearly 5.5K fish per mile of river. The amount of fish within the Bighorn, along with an average size of nearly 17”, makes this river an angler’s bucket list destination.

Best Times to Fish

The best times to hit the Bighorn river are in the spring months through the fall (April-November) with the hottest, regarding hatches and fish activity, being mid-June through early September.

While fish can be caught during the winter months, it tends to slow down with drops in temperature although, unlike other Montana trout waters, it remains ice-free in the winter due to the dam regulation.

Click on each season to see the best times of day to fish.


Late afternoon to evening


Early morning can be a great time on the river, but the Baetis hatches will occur around mid-morning


The best time to get on the river during the late summer months is early in the morning. Fishing can be hot all day, but the number of anglers and fishing pressure ramps up quickly. Late afternoons are also a great time to catch spinner action on the river.


Early fall (September-October) early morning is still hot to fish and late afternoon offers great spinner action

Hone your fly fishing skills

Before heading out to Blue Ribbon waters like the Bighorn river it's important to have your skills, and strategies dialed in. Our skill guides help build a foundation for success on the river.

Bighorn River Access Points

A majority of the blue ribbon portion of this river passes through Crow Tribal land and private ownership making access limited to waders.

Drifting the river is very popular and wading is allowed as long as you stay below the high water mark in the river if you find a good wading spot while floating.

The most popular launch sites include Afterbay Dam and 3-mile access point (Lind Ranch).

Further downstream the 13 mile (Bighorn access) and Mallards landing access point is the final public access point for the Bighorn river.

Tactics and Gear

Floating the Bighorn river is your best option for covering large portions of the river. The majority of the river is not accessible for wading opportunities except for limited shoreline access around the three major access points.


Your standard 5wt 9′ fly rod will be able to cast the most popular flies for the Bighorn as well as land the fish you hook up on. A larger 6 or 7wt rod is also a popular choice for those anglers looking to throw larger streamers or work the deep weed beds throughout the river for large holding trout.

The Bighorn offers fantastic insect hatches so dry flies are very popular. Nymphing, especially in the early spring, late fall, and winter months is the go to fishing method. Fishing streamers are also popular and give you the best chance at landing a trophy brown. In terms of specific tactics, there are some popular strategies that many anglers use on the Bighorn.

Streamers are great year round, but during winter months are especially effective at enticing a sluggish trout. Strip through slower, deeper runs and pools and look to hook up on a large brown.

Streamers Guide Nymphs Guide

These are not the most skittish fish, but it will still be to your advantage to use at least a 9’ to 10’ leader with another few feet of tippet especially when fishing dries.

While the dam usually maintains a flow rate that allows excellent fishing, keep on eye on the CFS. Anything above 7,000cfu is nearly unfishable.


During the PMD and Trico hatch be sure to stick around the river in the late afternoon as they are famous for excellent spinner falls and intense trout feeding. Be sure to have a few spinner or cripple imitations in your fly box.

Hatches and Flies of Importance

Call ahead to local fly shops for up to date hatch information and recommendations for good imitations.

Winter (December-February)

Midges: Sizes 18-28 pupa imitations in darker colors. Emergers will also land fish consistently. Can be effective year round, but other hatches are of more importance.

Scuds: Sizes 16-24 in orange or light olive colors.

San Juan Worms: Sizes 12-18 in pink, red, orange, and brown variations.

Streamers: Wooly Buggers in brown, red, and yellow color variations are very effective.

BWO: Sizes 16-24. Dun and cripple patterns work well.

Nymphs: BH pheasant tails and other mayfly nymph and emerger patterns sizes 16-24.

Spring (March-May)

Midges: Sizes 18-28 pupa imitations in darker colors such as black or purple zebra midges. Emergers will also land fish consistently.

BWO: Sizes 16-24

Nymphs: BH Pheasant Tails sizes 16-24 or other mayfly imitations in the nymphal stage can be effective

San Juan Worms: Sizes 12-18 in pink, red, orange, and brown variations.

Summer (June-August)

Midges: Similar sizes as previous seasons. Trout will feed on these insects year round, but more important food sources are now hatching in abundance.

BWO: Sizes 16-24

Little Yellow Sally: Sizes 14-20 in mid-June through July

PMD: Sizes 16,18. Hatches normally occur late June through August.

Caddis: Sizes 14-18. Black and tan caddis hatches occur Mid July into September.

Trico: Sizes 22,24. This hatch occurs right around the end of the Rainbow spawning period and results in some frenzied rainbow feeding.

Terrestrials: Larger grasshopper patterns sizes 2-10 and ant patterns sizes 14-20.

Fall (September-November)

BWO: Sizes 16-24

Tricos: Sizes 22,24

Terrestrials: Larger grasshopper patterns sizes 2-10 and ant/beetle patterns sizes 12-20.

Streamers: Wooly Buggers in brown, red, and yellow color variations

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