gallatin-river

Gallatin River is a river in Montana.

It ranks #6 among the 17 waters of Montana in the registry, and is of national prominence.

Also called The Gallatin.

Fished for trout (inferred from the species listed).

Species: rainbow trout, brown trout, cutthroat trout and mountain whitefish.

USGS GNIS record: 806320.

Stretches: Park Boundary to Big Sky and Spanish Creek Bridge to Three Forks.

Access points: Shedds Bridge and Spanish Creek Bridge.

Confluences: Missouri Headwaters State Park and Taylors Fork.

Big Sky to Spanish Creek Bridge (stretch). It is fishable. Whitewater stretch between Big Sky and the Spanish Creek area (BSG). OBG: the canyon from Sage Creek to Spanish Creek sees significant pressure.

It is upstream of Spanish Creek Bridge to Three Forks.

It is downstream of Park Boundary to Big Sky.

Gallatin Forks (access). It is fishable and launchable. BSG: float fishing becomes legal here, twelve miles upstream of Three Forks. Also called Gallatin Forks Access Site.

It is upstream of Logan Bridge.

It is downstream of Stubbs Bridge.

Logan Bridge (access). It is fishable and launchable. GG: floating allowed from the East Gallatin down to Logan Bridge on Highway 205 and on to Missouri Headwaters State Park (statement conflicts with BSG's Gallatin Forks rule; recorded as stated by each source).

It is upstream of Missouri Headwaters State Park.

It is downstream of Gallatin Forks.

Sage Creek (confluence). It is fishable. OBG: 'The canyon area from Sage Creek to Spanish Creek sees a significant amount of pressure'.

It is upstream of Spanish Creek Bridge.

It is downstream of Taylors Fork.

Stubbs Bridge (access). It is fishable.

It is upstream of Gallatin Forks.

It is downstream of Shedds Bridge.

Float: Gallatin Forks to Three Forks, from Gallatin Forks to Missouri Headwaters State Park, 12 miles.

Float: Logan Bridge to Missouri Headwaters State Park, from Logan Bridge to Missouri Headwaters State Park.

Sourced from 1 independent fly site.

Sources: bigskyfishing.com, glaciertoyellowstone.com, outsidebozeman.com and The Perfect Fly Store (retrieved 2026-10-20).

Hatches

Blue-Winged Olive

Stage: dun. Well sourced.

  1. Jan
  2. Feb
  3. Mar hatching
  4. Apr hatching
  5. May hatching
  6. Jun
  7. Jul
  8. Aug
  9. Sep hatching
  10. Oct hatching
  11. Nov
  12. Dec

Spring hatch late March to May; fall hatch mid-September into October. Best on overcast days around Big Sky and downstream; spring size 14-16.

Sources: Montana Angler, Montana Angler, Montana Angler

Pale Morning Dun

Stage: dun. Well sourced.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun hatching
  7. Jul hatching
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Begins late June, lasting through July; hatches at about 58F, sunny or overcast.

Sources: Montana Angler, Montana Angler, Montana Angler

Yellow Sally

Stage: nymph, adult. Well sourced.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun hatching
  7. Jul hatching
  8. Aug hatching
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Nymphs active from mid-June; adults from mid-June through early August; trout rarely key on adults.

Sources: Montana Angler, Montana Angler, Montana Angler

Salmonfly

Stage: adult. Well sourced.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun hatching
  7. Jul hatching
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Timing follows the end of runoff; Bozeman to the Yellowstone Park boundary. Adults come off at 54-58F; wade-fishable.

Sources: Montana Angler, Montana Angler, Montana Angler

Spruce Moth

Stage: adult. Well sourced.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul hatching
  8. Aug hatching
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Gallatin Canyon south of Bozeman and Big Sky; size 14-16.

Sources: Montana Angler, Montana Angler, Montana Angler

Golden Stonefly

Stage: adult. Well sourced.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun hatching
  7. Jul hatching
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Right after or during the salmonfly hatch; size 8-12.

Sources: Montana Angler, Montana Angler, Montana Angler

Western March Brown

Stage: dun. Well sourced.

  1. Jan
  2. Feb
  3. Mar
  4. Apr hatching
  5. May hatching
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Sporadic; needs overcast, 44-48F water and light wind; size 12-16.

Sources: Montana Angler, Montana Angler, Montana Angler

Caddis (incl. Mothers Day)

Stage: adult. Well sourced.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May hatching, peak
  6. Jun hatching, peak
  7. Jul hatching, peak
  8. Aug hatching
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Peak: early May, June and July

River usually fishable after runoff by June 20; thick right after runoff and well into July.

Sources: Montana Angler, Montana Angler, Montana Angler

October Caddis

Stage: adult. Well sourced.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep hatching
  10. Oct hatching
  11. Nov
  12. Dec

As early as late September, typically peaking late October; sporadic; size 8-10.

Sources: Montana Angler, Montana Angler, Montana Angler

Grasshoppers, ants, beetles

Stage: adult. Well sourced.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul hatching, peak
  8. Aug hatching
  9. Sep hatching
  10. Oct
  11. Nov
  12. Dec

Peak: by late July

Hatches turn sporadic by then.

Sources: Montana Angler, Montana Angler, Montana Angler

Salmonfly

Single or templated source.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul hatching
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Dates are for the Park headwater section; the canyon below runs earlier. About two weeks; the canyon stretch beyond the park has a much heavier hatch.

Sources: The Perfect Fly Store

Skwala

Stage: nymph, adult. Single or templated source.

  1. Jan
  2. Feb
  3. Mar hatching
  4. Apr hatching
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Templated chart only: primary March-April, beginning as water climbs out of the low 40s; size 8-12. Generic regional template, not water-specific; the river's own chart does not list this insect.

Sources: The Fly Fishing Place, The Fly Fishing Place, The Fly Fishing Place

Grasshoppers, ants and beetles

Single or templated source.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul hatching
  8. Aug hatching
  9. Sep hatching
  10. Oct
  11. Nov
  12. Dec

Dates are for the Park headwater section; the canyon below runs earlier.

Sources: The Perfect Fly Store

Midge

Single or templated source.

  1. Jan hatching
  2. Feb hatching
  3. Mar hatching
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Templated chart only: primary January-March and November-December, secondary October; size 18-22. The template is shared across several rivers; treat as generic regional, not water-specific. The river's own chart does not list this insect.

Sources: The Fly Fishing Place, The Fly Fishing Place, The Fly Fishing Place

Spotted Sedge

Single or templated source.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul hatching
  8. Aug hatching
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Dates are for the Park headwater section; the canyon below runs earlier.

Sources: The Perfect Fly Store

Mahogany Dun

Stage: dun. Single or templated source.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep hatching
  10. Oct hatching
  11. Nov
  12. Dec

Templated chart only: gray afternoons; size 14-16. Generic regional template, not water-specific; the river's own chart does not list this insect.

Sources: The Fly Fishing Place, The Fly Fishing Place, The Fly Fishing Place

Flav (Small Western Green Drake)

Single or templated source.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul hatching
  8. Aug hatching
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Dates are for the Park headwater section; the canyon below runs earlier. Lasts almost a month from mid-July.

Sources: The Perfect Fly Store

Pale Morning Dun

Single or templated source.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun hatching
  7. Jul hatching
  8. Aug hatching
  9. Sep hatching
  10. Oct
  11. Nov
  12. Dec

Dates are for the Park headwater section; the canyon below runs earlier. The most consistent mayfly.

Sources: The Perfect Fly Store

Yellow Sally

Single or templated source.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul hatching
  8. Aug hatching
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Dates are for the Park headwater section; the canyon below runs earlier.

Sources: The Perfect Fly Store

Green Drake

Single or templated source.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun hatching
  7. Jul hatching
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Dates are for the Park headwater section; the canyon below runs earlier. Third or fourth week of June, lasting about three weeks; a light hatch.

Sources: The Perfect Fly Store

Blue-Winged Olive

Single or templated source.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun hatching
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Dates are for the Park headwater section; the canyon below runs earlier. Early-season hatch in June; late-season hatch from late September or early October.

Sources: The Perfect Fly Store

Green Sedge

Single or templated source.

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun hatching
  7. Jul hatching
  8. Aug hatching
  9. Sep hatching
  10. Oct hatching
  11. Nov
  12. Dec

Dates are for the Park headwater section; the canyon below runs earlier.

Sources: The Perfect Fly Store

Also named, timing not yet researched: Trico.

Access, closures and rules change; check with the state agency before you go.