June Fishing on the Gallatin River

June weather, stream flows, and summary

June on the Gallatin River is an exercise in patience. In most years the Gallatin River comes into prime form in the second half of the month. In some years it happens sooner and in some years it happens later. The ability to fish the Gallatin River depends entirely on when snowmelt runoff peaks and streamflows begin to drop. On average, the Gallatin River’s stream flows crest around June 10. However, how high the streamflows run and how quickly the river drops and clears is a day-to-day prospect in early and mid-June. Because the catchment area consists of two large mountain ranges—the Gallatin and Madison Ranges—much of the snowpack needs to melt before streamflows and clarity provide ample fishing conditions. 

By early June snowpack data can paint a detailed picture to help forecast when the Gallatin River may crest and begin to drop. Because the average annual peak streamflow occurs around June 10, by the second week of June the day-to-day forecast is the best gauge for when the river might come into form. When it does drop and clear enough to fish—typically below 2,000 cubic feet per second (cfs) and with about 12 inches of visibility—the river is one of the best freestones in Montana. In June the most consistent fishing occurs on the river around Big Sky, Montana. Once the river enters Gallatin Valley, streamflows tend to still be too high and fast for consistent fishing. 

The Taylor Fork is a major tributary of the Gallatin River. This tributary joins the Gallatin River a few miles north of the boundary of Yellowstone National Park. The Taylor Fork often runs muddy while the river coming out of Yellowstone National Park runs clear, providing clearer water fishing options. However, in June the water temperatures on the Gallatin River above the Taylor Fork are often considerably colder, thus less hatches of insects occur making for less consistent fishing. 

The Gallatin River sees a diversity of weather patterns in June. Early June has an average daily high temperature hovering around 65 degrees F while later in the month average daily high temps tick close to 80 degrees F. Later in the month the prevalence of sunny days far out-weigh overcast days. Because the weather is varied in June, so is the river’s condition. If the first half of June is cold and rainy, snowmelt runoff is delayed, forcing anglers to wait until later in June for a fishable river. If the first half of June is warm and dry, snowmelt runoff may happen sooner, creating the possibility for the river to be in prime shape by June 10th. 

When the Gallatin River becomes clear enough to fish, hatches of salmonflies, Golden stoneflies, and Yellow Sally stoneflies dominate. Golden stoneflies are an important hatch occurring shortly after salmonflies. Pale Morning Duns (PMDs) and various caddis species have strong emergence in June. With a diverse and abundant cornucopia of hatching insects, June fly fishing on the Gallatin River can be consistent and action-packed—it is just necessary to be patient for the first couple of weeks of the month.  

June fishing: what to expect

It is best to assume the Gallatin River will not be fishable until the second week of June. There are exceptions—an unseasonably frigid and dry cold front moves in during early June or the winter’s mountain snowpack is well below annual averages. Assuming those two factors are at bay, by mid-June, the weather forecast and streamflows can provide enough insight to how the river will fish in the middle and later part of June.

Once the Gallatin River drops below 2,000 cfs it can be all systems go in the canyon section of the river between Big Sky and Bozeman. Except for the last 15 miles of the Gallatin River—from the confluence of the East Gallatin River and the Gallatin River near Manhattan downstream to its confluence with the Jefferson and Madison Rivers—the Gallatin River is a walk-and-wade fishery. Fishing from boats is prohibited on the river upstream from the confluence of the East Gallatin River. 

Anglers planning to fish the Gallatin River in June can expect a river that is full, high, a bit off-color, and fished best from the bank. Water clarity on the Gallatin River in June rarely improves past a few feet of visibility, but because the Gallatin River is full of stonefly nymphs the trout hang close to the bank. The river clarity often takes on an olive green hue. This dark greenish color is referred to by locals as “Gallatin Green.” And, as green means go, so it goes for the Gallatin River…and expect a river in prime shape. 

Because the fish are holding near the bankside structure, fish leaders that are short and stout—it is common to fish 7-foot 1X leaders with short tippets. For stonefly nymphs choose large black or brown patterns in sizes 2 to 8. For streamers, choose a tippet no less than 10 or 12-pound breaking test. For dry fly fishing, choose large dry flies in sizes 4 to 8. Be sure to fish a very stout tippet as well, nothing less than 10-pound test.  

By late June PMDs and caddis may begin to hatch. Streamflows may still be high but clarity may have improved to more than two feet. Leaders can be lengthened to 9 foot 4X and single dry flies in appropriate sizes to match hatching PMDs or caddis are ideal. 

Where to find June trout on the Gallatin

Finding trout on the Gallatin River in June is a book of two chapters. The first chapter consists of fishing the river immediately after it drops and clears, typically around June 10th. It may take a few days for streamflows and clarity to be favorable for fishing, but when that occurs, salmonflies and Golden stoneflies can hatch in abundance. Because salmonflies and stoneflies require structure from which to hatch, trout will be found near willows, submerged rocks and branches, and other structures. 

Stoneflies hatch by clinging to structure and then emerging from an exoskeleton, trout follow the insects and become opportunistic feeders as the current washes away the structure-clinging nymphs. The fast and high flows in June force trout to hang near structure and in slow water. Eddy-lines, foam-lines created by eddies, and any slow water are places to find trout on the Gallatin River in June.

The second chapter begins later in June as the river continues to drop in flows. Pale Morning Duns (PMDs) and caddis may hatch in abundance. In most years late June sees the Gallatin River with streamflows clear enough for trout to feed on hatching PMDs and caddis. 

When PMDs and caddis hatch, often in the later third of the month, streamflows are lower and trout can now hold in riffles, runs, near mid-river shelfs, and even on shallow flats. On the Gallatin River in June during a PMD or caddis emergence, trout can be found at the tail end of a shelf or riffle gorging themselves.

Important June hatches

The salmonfly hatch is the most anticipated hatch of the year on the Gallatin River. This hatch occurs in mid or late June. However, whether river conditions allow for fishing is variable from year to year. In most years the river is below 2,000 cfs by June 10th and has enough clarity anglers can effectively fish the salmonfly hatch. In other years the river is too high and too muddy and the fishing begins in late June. 

After salmonflies hatch, Golden stoneflies, Yellow Sally stoneflies, Pale Morning Duns (PMDs) and caddis dominate. After salmonflies and Golden stoneflies hatch, PMDs and caddis provide ample opportunities for dry fly fishing. After snowmelt runoff peaks, the Gallatin River often drops and clears quickly so hatching insects can change daily as well. Because of this, the diversity of hatches on the Gallatin River is part of the excitement of fishing this unique freestone. 

Gallatin River fly box for June

Stonefly nymphs in brown and black in sizes 8 through 10

Salmonfly dry flies in sizes 4 to 8

Golden stonefly dry flies in sizes 6 to 10

Yellow Sally stonefly dry flies in sizes 10 and 12

Caddis pupae in sizes 10 to 16

Caddis dry flies in sizes 10 to 16

Pale Morning Dun nymphs in sizes 12 to 16

Pale Morning Dun emergers in sizes 12 to 16

Pale Morning Dun dry flies in sizes 12 to 16

Sculpin patterns in sizes 2 to 6

Streamers in olive, black or brown in sizes 2 to 6