The Glorious Gallatin

Though smaller and less storied than its neighbor, the Madison, the Gallatin deserves a day or two if you’re visiting Southwestern Montana. Originating in Yellowstone National Park, the Gallatin flows through one of the most scenic river corridors in the Rockies. 120 miles downstream, it joins the Madison and Jefferson Rivers to form the headwaters of the Missouri.

From meandering alpine meadows; to a pine studded, narrow canyon; to a classic, riffle-pool valley bordered by farms and ranches; the Gallatin River offers a surprising diversity of fly fishing. The Gallatin has something for everyone, from first timers to dedicated anglers.

A Famous Flow

Thirty years after its release, A River Runs Through It remains the most iconic fly fishing movie ever produced. Though the story takes place on the Blackfoot River, producers filmed most of the fishing in Gallatin Canyon. Fans of the movie will remember a towering limestone butte, Storm Castle Peak, a view you can experience for yourself while fly fishing on the Gallatin River.

This article outlines Gallatin River fly fishing: introducing the different sections and offering specific recommendations regarding access, times of year, and fly fishing methods. Check out the Angler’s Guide to the Gallatin River for a month by month breakdown of hatches, flies, and techniques.

A Brief History of The Gallatin River

Evidence of human habitation along the Gallatin River dates back more than 12,000 years. The canyon created a natural migration route between the plains and the mountains for buffalo and the people who depended on them. Numerous tribes used this corridor for hunting, warfare, and diplomacy.

When Meriwether Lewis reached the headwaters of the Missouri River in 1805, he named the three tributary flows for political luminaries of the time: Thomas Jefferson, James Madison, and Albert Gallatin. While Thomas Jefferson and James Madison have remained relevant, Albert Gallatin’s notoriety has not proven so enduring. Gallatin’s legacy is pretty much limited to his namesake river, the surrounding county, and National Forest.

Fishes of the Gallatin

Fish stocking between the late 1800s and early 1970s altered most of our rivers, and the Gallatin is no exception. Once dominated by westslope cutthroat trout, arctic grayling, and mountain whitefish, rainbow trout from the West Coast and brown trout from Europe are now most common. Pockets of cutthroat and grayling persist in tributaries but are rarely seen in the main river.

Montana Fish, Wildlife, and Parks estimates a population of around 3,000 catchable sized trout per mile. Trout sizes average between 6 and 12 inches—smaller than than the Madison or Yellowstone—but you’ll find plenty of fish in the 14-16 inch range and the occasional tank. The lower Gallatin, however, sees good numbers of fish between 18 and 20 inches.

Section-by-Section Guide to Fly Fishing the Gallatin River

Yellowstone National Park to Big Sky

The Gallatin exits Yellowstone National Park as a small, meandering stream. Wide open meadows and gentle current make for easy wading and casting. The river winds its way through oxbows and bends along grassy banks and shudders over shallow riffles. These 25 miles are readily accessible but can be fickle. There are plenty of trout, but you’ll have to walk between holding water.

Starting in April, baetis and midges draw fish to the surface. Caddis start in May and continue to make regular appearances all summer. Salmonflies and golden stones show up in late June and offer exciting fishing if the water is clear. Because this part of the river has long shallow riffles, it’s particularly good PMD habitat, and you can find fish looking up for these yellow mayflies throughout July and into August. Mid to late August brings out the terrestrial insects. Grasshoppers work on certain days, but the fish here seem to prefer smaller flies, so ants tend to be more productive. As water temperatures cool off in September and October, baetis return and can bring up good numbers of fish.

Because much of this water is relatively shallow, dry flies and dry droppers are a good bet. Fish heavy nymph and indicator rigs through deeper holes if you’re not finding fish in the riffles.

Fins and Feathers Fly Fishing Guide Pro Tip: During runoff and after rain events, much of the sediment in the Gallatin comes from the Taylor’s Fork, and fish migrate into the clearer water. Go above the Taylor’s Fork when the rest of the river is off color.

Big Sky to Spanish Creek (Gallatin Canyon)

Just upstream from the turn off for Big Sky, the West Fork nearly doubles the size of the Gallatin. The mountains close in on the river, creating a 30 mile cathedral of rock and moving water. The combination of additional flow, a tighter constriction, and a drop in elevation dramatically changes the river’s character.

The Canyon is the most famous and popular portion of the Gallatin. Highway 191 parallels the river, allowing ample and easy access to the numerous deep holes, long runs, and bouldered pocked water. In July and August, the crowds get thick, but the fishing holds up. Trout and insect populations are dense, so even when RV traffic grinds the highway to a crawl and the obvious spots look like the Kenai in salmon season, you can do well targeting water in-between holes.

The heart of the Canyon features “The Mad Mile,” a series of rapids popular with whitewater runners. Kayaks and rafts are common in the Canyon, but fishing from boats is prohibited. You can only use boats for transportation between spots, and must get out of the boat before casting. Do not float the Mad Mile unless you’re with an experienced rower.

Bug life in the canyon is prolific thanks to cold, well-oxygenated water. Even when other rivers and streams in the area get warm in the late summer, Gallatin Canyon remains cooler. Hatches here are similar to what you’ll find upstream. Baetis and midges pop in the late winter and early spring, and can provide great dry fly days before spring runoff arrives. Some years, the salmonfly and golden stone hatches in the canyon can be exceptional. Even if the water is stained, fishing big bugs close to the banks can be effective. If it looks like chocolate milk, however, fish elsewhere.

After runoff subsides, dry fly season settles in. In July, PMDs and caddis hatch in good numbers. Look for fish up on mayflies during the day and targeting caddis just before dark. Yellow sallies follow the PMDs and keep the fish looking up. Typically, the earlier in the season you fish, the bigger a dry fly you can get away with. As the water drops and clears and the fish see more and more flies, you’ll have to start downsizing, extending your leader, and more accurately matching the hatches.

In August, aquatic insects taper off, but the dry fly fishing continues. Depending on the weather in a given year, Gallatin Canyon can see a huge emergence of spruce moths. These are true moths that live in the many spruce pines along the river corridor. When conditions are favorable, usually drier years, they come out in numbers and the fish go crazy for them. Spruce moth patters are usually a good bet from mid-August to mid-September.

Fins and Feathers Fly Fishing Guide Pro Tip: Nymph the whitewater. The Mad Mile may be popular with boaters, but it doesn’t see nearly as many anglers as the rest of the Canyon. The water is big and swift, but trout stack up in the slack pockets and slow seams. Tightline nymph tactics, like Euro nymphing, can produce lots of fish.

Spanish Creek to Manhattan

Below Spanish Creek, the Gallatin transforms once again. The narrow canyon abruptly ends, the rock walls and spires peel away, and the valley opens up into a wide, fertile, agricultural plain. The river spreads out and slows down, making it much easier to wade. Most of the valley is private land, but a handful of public access points offer legal entry. Stay below the high-water mark to avoid trespassing. Landowners do not appreciate anglers on their property. Diminished access means fewer people, but the spots near public access still see a lot of traffic. Walking for a half hour or so before you start fishing will greatly improve your odds. This stretch is relatively straight forward to read with well-defined pools and runs, all of which hold good numbers of trout.

Insect populations aren’t as dense in the valley as the canyon, partially because it gets dewatered for agriculture during the summer. There are plenty of bugs, though, and the dry fly fishing can be excellent on the right days. Before runoff, baetis bring fish to the surface in slower glides and tailouts. Salmonflies and golden stones are less prolific than upstream, and this part of the river is often off color when the big bugs hatch. After the river drops and clears, you’ll find good PMD action during the day with caddis coming off in the evening.

August and September bring tricos, tiny black mayflies that can be maddening to fish due to their diminutive size, but are beloved by trout. Fish tiny trico spinners in the morning, then switch to grasshoppers, ants, and spruce moths in the afternoon with a dropper beneath. The further you go downstream, the more water gets siphoned off for crops. Below Axtell Bridge, the Gallatin can get pretty bony in late summer and water temperatures can get too warm to ethically fish for trout. In the fall, water levels rise, baetis return, and the dry fly fishing ramps back up. Fishing a BWO emerger in the autumn can produce some of the best dry fly fishing of the season.

Fins and Feathers Fly Fishing Guide Pro Tip: Explore the side channels. Spring and early summer runoff fills the valley with fishable side channels. Though these will dry up as the season progresses, fish take full advantage of them while they can, and you should too. Explore every channel and side sloughs you find. You might get lucky and score some morel mushrooms hidden in the grass as well.

Manhattan to Missouri River Confluence

Downstream from the small town of Manhattan, Montana, creeps the final 15 miles of Gallatin River fly fishing. This lowest stretch feels like a completely different river from the frothing, icy churn of the canyon. Placid and calm, the lower Gallatin winds through alfalfa fields and meanders past ancient hay barns. The East Gallatin joins the mainstem, adding back some of the water lost upstream to agriculture and restoring fishable flow. The lower Gallatin fishes well before and just after runoff, but usually becomes too warm in late July and August. When autumn arrives, it turns back on.

Below Nixon Bridge, anglers are allowed to fish from boats, and this is where Fins and Feathers guides really enjoy taking clients fly fishing on the Gallatin River. Though trout populations are not as high as those found in the Canyon, there are some big ones down here. When conditions are right, our guides will be happy to help you search for big browns and rainbows.

Hatches are sparse. Tricos will bring some fish to the surface on August and September mornings, but we generally fish nymphs and streamers. Small crayfish patterns are staples with hare’s ears, copper johns, or San Juan worms hanging off the back.

Fins and Feathers Fly Fishing Guide Pro Tip: Small, white streamers. Dead drifted, slowly stripped, or swung, small white streamers are highly effective on the lower Gallatin for both rainbows and browns.

The Takeout

Though less famous than the Madison, Missouri, or Yellowstone Rivers, fly fishing on the Gallatin River should not be underestimated. Standing in the wild, freestone flow of the Canyon, looking up at towering limestone faces and steep hillsides studded with vibrant pines—the beauty of the place alone is worth a visit. Add in thousands of trout per mile that consistently eat dry flies, and you’ve got a river that’s not to be missed.

The Fins and Feathers Guide Service fly fishing guides know every seam and pocket of this river, from Yellowstone National Park to the headwaters of the Missouri. We’ve been creating fly fishing memories for our clients on the Gallatin for more than two decades and can help you experience the full diversity of this fishery, from casting dry flies through pocket water in the canyon to chasing the fish of your dreams in the lower reaches.

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