Gallatin River Montana Fly Fishing - Where to Trout Fly Fish

by Huston Heatherly

The Gallatin river in Montana is a freestone river, and in terms of the typical trout habitat anglers have in mind it fits the prototype.

Location

The headwater of the Gallatin River begins in the Yellowstone National Park and passes through the Gallatin Canyon and by the town of Big Sky, MT to the Gallatin Valley.

The river runs for nearly 90 miles and eventually runs into the Madison and Jefferson rivers to form the Missouri River. The largest airport near river access is the Gallatin Field Airport (BZN) in Bozeman, MT.

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About the River

The Gallatin is a freestone river, and in terms of the typical trout habitat anglers have in mind it fits the prototype. The river is made up of long stretches of riffles, runs, and deep pools with boulders scattered throughout providing prime trout lies from the current.

As the river runs through Montana, it changes its character several times. From a slow meandering meadow stream, to faster riffle, run, pocket water, back to a classical freestone river the Gallatin provides all types of fly fishing the angler might be interested in from delicate dry fly presentation, heavy nymphing, to catch all attractor patterns in fast moving riffles and runs.

As this is a freestone river, it is prone to water fluctuations and varying temperatures. Its run-off usually occurs around the beginning of May and proceeds through mid to late June.

The Gallatin offers ample opportunities for wading, which is especially important for those looking to make the trip and not pay for guide services on a float.

Most anglers will recognize this river as the location for the film “A River Runs Through It” and upon arrival will immediately notice the fly fishing paradise from the trout in the river to the landscape around it.

Types of Fish

The Gallatin River boasts a diverse range of fish species from brown and rainbow trout to cutthroats and whitefish.

From Yellowstone to Spanish Creek the trout population is at an excellent rate of 2,500 to 3,000 fish per mile. This can be considered a meadow stream at this point and has excellent hatches throughout the summer and fall months.

After Spanish Creek, where the river enters a canyon, the water picks up speed. While there may be fewer fish, this stretch is known to harbor hungry and aggressive trout.

Below Cameron Bridge the river takes on a classical freestone look, and the fish population drops pretty dramatically. This stretch is known to hold trophy browns.

Best Times to Fish the Gallatin River

The runoff period for the Gallatin River usually begins around the start of May and continues until mid to late June before the river straightens up and the fishing turns hot again. Hitting the river before the runoff and immediately afterward will result in hot fishing and many trout on the end of your line.

While the activity of fish in the river drops with the temperature in the winter, there are warm springs that feed into the river near Yellowstone and Big Sky making these sections excellent winter fisheries.

During the late summer and fall months, being on the stream early in the morning and late afternoon usually puts you in the river when the highest trout activity is taking place.

Gallatin River Access Points

There are numerous access points available for the angler all along Hwy 191.

Tactics and Gear

Regarding self-planning trips without the need for boat rentals or guide services, the Gallatin is a fantastic destination as it presents numerous access points along HWY 191 and miles of river able to be waded. Lots of this river is restricted to wading so if you are planning a float trip be aware of these areas.

Your standard fly fishing techniques and equipment will consistently land you fish on the Gallatin. With a high fish population most likely trout lies will be holding fish.

The Gallatin offers a lot of wadable river, and it is in your interest to cover as much water as possible. Do not linger too long at only a few holes close to your access point, cover as much water as possible to increase your chances of landing fish.

Throwing a nymph is a great tactic and will usually lead to successful fishing trips. It is important to get your flies down deep enough and quick enough to holding trout.

In the canyon section of the river where the water is much swifter, attractor or terrestrials are extremely effective and leads to some vicious topwater strikes from hungry trout.

The Gallatin river is often associated with large stonefly hatches leading to excellent dry fly fishing with huge dry imitations. Stoneflies will crawl to the bank to hatch into their adult form so look to fish these areas. The bulk of the stonefly hatch occurs from Cameron Bridge and downstream, but you can have success upstream from this area as well.

Hatches and Flies of Importance

Winter (December-February)

Midges: Sizes 16-24

Little Black Stone: Sizes 16,18

Caddis: Sizes 14-18 in various colors such as black, brown, tan, and olive.

Streamers: Leeches and Wooly Buggers sizes 2-10

Spring (March-May)

Midges: Sizes 16-24

Caddis: Sizes 14-18 in various colors such as black, brown, tan, and olive.

PMDs: Sizes 16-20

BWO: Sizes 18-22

Streamers: Leeches and Wooly Buggers sizes 2-10

Be Prepared to Match the Hatch in Montana

Our curated fly boxes give you a great foundational fly collection to be able to match the hatch on the Gallatin. Organized by type and size these boxes take the headache out of building an effective fly box.

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Summer (June-August)

Midges: Sizes 16-24

Salmonflies: Golden Stone (4-10), Yellow Sally(12-16), Salmonfly (2-8).

Caddis: Sizes 14-18 in various colors such as black, brown, tan, and olive. Swing patterns at the end of the drift in the afternoon to imitate egg laying female.

Green Drake: Sizes 10-12

PMDs: Sizes 16-20

Tricos: Sizes 18-22

Terrestrials: Grasshoppers (8-14), Ants (16-20), and Beetles (12-18)

Streamers: Leeches and Wooly Buggers sizes 2-10