Hiking the Gallatin Riverside Trail in the Gallatin Canyon
Location: Gallatin Canyon – Storm Castle to 35 MPH Bridge Along Eastern Banks of Gallatin River
Trailhead: Storm Castle Trailhead (19.0 miles north of Big Sky) or 35 MPH Bridge (13.4 miles north of Big Sky)
Type: Out and Back or One Way
Distance: 3.1 miles one direction, 6.2 round trip
Time: 1.5 hours one direction
Elevation Storm Castle TH: 5454 ft
Elevation 35 MPH Bridge: 5525 ft
The Gallatin Riverside Trail meanders along the eastern banks of the Gallatin River between the Storm Castle and the 35 MPH bridge on Highway 191. The trail weaves through vibrant green lodgepole pine forests, over moss covered rocks, along both sandy and rocky beaches of the Gallatin River, through open meadows, below cliffs of limestone and gneiss, and parallels the mesmerizing clear waters of the Gallatin River.
The Gallatin Riverside Trail, sometimes called the Gallatin River Trail #137, is a multi-use trail for hikers, climbers, horses, and bikers. The hike is a nice way to spend a few hours outdoors in the beauty of Montana. There is minimal elevation gain on the hike making an easy adventure for people of all abilities.
It’s a stunning hike that can be done one way or as an out and back. For our adventure, Mia, River, and I parked a car at the 35 MPH Bridge on 191 (5525 feet) and one at the Storm Castle Trailhead (5454 feet). The Storm Castle turn off to the 35 MPH Bridge is 3.8 miles on 191. That way we could enjoy the hike and make it back to Big Sky in time to get some things done. It’s possible to go out and back, which makes for a longer, round trip hike.
The Storm Castle Trailhead is located in the Gallatin Canyon. As we approached from Big Sky, the Storm Castle turnoff is just after Beckman Flats and 17.2 miles north of the Big Sky turn. It’s well marked and with a quick turn to the east, you will cross the bridge over the Gallatin Canyon. Turn right and follow the well maintained dirt road for 1.8 miles. You’ll quickly pass a helicopter base and a bit later a church camp turn off. The trailhead is located on the south side of Storm Castle peak on the left of the road. Usually it has plenty of parking, but there are several trails, including the Storm Castle Peak Trail, and climbing routes nearby, so it can be crowded. The Gallatin Riverside trail begins on the south side of the road – across the road from the trail info sign.
The trail immediately crosses a bridge over Squaw Creek and heads into a thick forest. There is a bit of elevation gain right away as the trail heads up Garnet Mountain. In about a quarter mile the trail forks. An obvious sign shows that the right path leads down to the Gallatin Riverside Trail and the left heads up to Garnet Mountain and the Lookout Tower. Head right and soon a few switchbacks lead down to a large meadow.
Cross the meadow next to the Gallatin until you go through a gate. Here the trail downsizes into a nice single track. The trail wanders next to the river for the rest of the hike. There are several sandy beaches and a few rocky ones as well. There are fantastic views of massive gneiss formations and limestone cliffs. Storm Castle looms down river to the north. Bring a camera and plan to have a snack next to the river. There is plenty of water for your four-legged companions too.
In some seasons the river is busy with kayakers and rafters. Fishermen are frequently seen trying their luck on the banks of the Gallatin River. The trail near the 35 MPH Bridge is well trodden and sees frequent traffic from climbers looking to climb in the Gallatin Canyon. A good section of trail could use someone skilled with a machete to give it a bit of a trim, but overall the trail is in good shape and it’s easy to follow.
As you approach the 35 MPH bridge, be sure to head underneath the bridge to avoid crossing highway 191. It’s busy and hard to see traffic in both directions.
The Gallatin Riverside Trail is an ideal trail from Spring to Fall. If you have a spare 1.5 to 2 hours, head into the canyon and go for a peaceful walk next to the rushing Gallatin. It’s relaxing, stress free, and straight forward.
According to the Gaia GPS app, Mia, River, and I covered 3.1 miles and 550 vertical feet one way. That makes it 6.2 miles round trip. Interestingly enough, most guidebooks say that the Gallatin Riverside Trail is 2.25 miles and 200 vertical feet of elevation gain going one way. A round trip would be 5.5 miles. I know Gaia GPS may not be the most accurate resource in the world, but even Google Earth says it’s 2.35 miles in a measured straight line between Storm Castle Trailhead and the 35 MPH Bridge. Not a huge difference, so either way it’s an easy 2.25 to 3.1 miles of walking with minimal elevation gain for such a beautiful hike.