A Guide to the Sun River, Montana

Will Beck
Last Updated: March 4th, 2023

The Sun River flows from the Flathead National Forest at the South and North Forks confluence. The river flows southeast away from the mountains and empties into the Missouri River at Great Falls.

Although the waters of the Sun River are mainly used for irrigation, there are plenty of recreational and fishing opportunities near the Gibson dam.

A Guide to the Sun River, Montana

History of the Sun River

sun river montana

The Sun River got its name from the Indian word “Nataeosueti,” meaning “Medicine” or “Sun” river.

Captain Lewis, one of the explorers of the Lewis and Clark Expeditions, followed this river downstream. On July 11, 1806, Capt. Lewis passed near the section where the Sun River empties to the Missouri River.

The river meanders through the town of Sun River. John Largent established this town in 1867 and opened a post office and a store.

He partnered with Joe Healy and built a toll bridge across the Sun River. The bridge helped people in the river to profit from the new gold mines and the Mullan Road traffic.

Geography & Stats

The Sun River’s headwaters are at the confluence of the South and North Fork in Flathead National Forest.

The South Fork originates from Sun Lake in Lewis and Clark County and flows northwest. The North Fork originates in the Bob Marshall Wilderness and flows south for approximately 20 miles (32 km), where it meets the South Fork.

The Sun River begins where the two Forks meet, then flows east, southeast, and east past the towns of Simms, Sun River, and Vaughn. It flows from an elevation of 4,728 ft. (1,441 m).

The river flows downwards for five miles into Gibson Reservoir, held back by Gibson Dam. The Sun River flows for three miles to the Sun River Diversion Dam. The water between Gibson Reservoir and the Sun River Diversion Dam consists of whitewater.

The river flows downstream past the Sun River Canyon, and the whitewater ends.

The Sun River Canyon provides scenic views of the Rocky Mountain Front. At this point, the river’s extensive rapids offer perfect spots for floating and fishing.

After about eight miles from the Sun River Diversion Dam, the river flows past the town of Vaughn, where it slows and runs muddy.

The slow current and high winds along the Rocky Mountain Front make it difficult to paddle in a canoe or raft. Below Vaughn, the Sun River slowly meanders downstream for seventeen miles and joins the Missouri River at Great Falls.

Attractions at Sun River

Gibson Dam

gibson dam
Image: Dustin Moore

The Gibson Dam is a 199 feet high and 960 feet long concrete arch dam located south of the Bob Marshall Wilderness on the Sun River.

The dam forms the Gibson Reservoir, storing up to 119,003,000 m³ when full. It has a shoreline of about 15 miles (24 km), covering over 1,296 acres (524 ha) when full.

Gibson Dam provides irrigation water for the Sun River Project. During summer, the dam captures snowmelt from the valley and releases it for irrigation.

Visitors to the Gibson Dam can hike along the 26.1 km out-and-back reservoir trail to capture the best views of the dam. It’s a well-maintained trail that takes about 6 hours and 11 minutes to complete.

The Gibson Dam offers an opportunity for boating, fishing, camping, and picnicking.

Great Falls

The Great Falls comprises a series of waterfalls at the Sun River’s confluence with the Missouri River. The five falls are Black Eagle, Colter, Rainbow, Crooked, and Big Falls. These falls have a total height of 187 feet (57 m), with the Big Falls having the longest drop of 87 feet (26.52 m).

Visitors can explore the five drops or walk three miles south to the Lewis and Clark Interpretive Center.

The 60-mile River’s Edge Trail connects several Great Falls attractions. The trail offers spectacular views of waterfalls, mountains, reservoirs, river canyons, prairies, and hydroelectric dams.

Visitors enjoy opportunities for jogging, biking, skating, mountain biking, and hiking along this trail.

First Peoples Buffalo Jump State Park

first peoples buffalo jump state park
Image: Jimmy Emerson, DVM

The First Peoples Buffalo State Park is a 1,481-acre state park in Cascade County, about 3.5 miles from the town of Ulm. The park is a National Historic Landmark and the largest buffalo jump in the world.

The park features a historic buffalo jump, the Ulm Pishkun, used by the North American Native tribes. Visitors can access the park via Taft Hill Road to get to the base of the cliff or via Ulm-Vaughn Road to get to the visitor’s center, the cliff’s summit, and the slope.

This state park is home to coyotes, black-tailed prairie dogs, American Badgers, mule deer, rattlesnakes, pronghorns, and red-tailed hawks.

Plant species in the park include blue grama, prickly pear cactus, needle-and-thread grass, and Bluebunch wheatgrass.

Freezeout Lake Wildlife Management Area

Freezeout Lake Wildlife Management Area is a wildlife viewing area on Freezeout Lake, located about 40 miles west of Great Falls. Over 200 birds congregate here as their staging point each year. Freezeout lake hosts millions of migratory birds, such as the snow geese that migrate from California.

Birdwatchers flock at Freezeout Lake during spring to watch hundreds of thousands of snow geese arriving in huge squadrons. The lake hosts other species, such as ducks, swans, herons, shorebirds, and Tennessee warblers.

Camping is available for visitors who wish to spend a few days watching the birds. The management area has adventurous and family-friendly trails that offer breathtaking views of the lakes, surrounding farms, and the birds.




The Sun River has massive irrigation demands preventing successful trout reproduction. However, the water above Gibson Reservoir provides excellent habitats for trout. Anglers visiting the Sun River have exceptional fly fishing opportunities at Gibson Dam and above.

The North and the South Fork rivers have low fishing pressure in a remote setting. While anglers might not catch huge fish in the two forks, fly fishing allows them to catch cutthroats, rainbows, and brook trout.

Floating and Boating

The Sun River is floatable below Gibson Dam. Visitors can enjoy floating on the three miles between Gibson and Sun River Diversion Dam. The water in this section of the river is fast and bouncy, making it a perfect spot for experienced paddlers.

After leaving the Sun River Diversion Dam, the river flows through Sun River Canyon. The nine-mile stretch has a narrow width and many rocks and is only suited for experienced paddlers. Boating is available in Gibson Dam, Sun River Diversion Dam, and below the town of Vaughn.


camping river side

The Sun River and the surrounding area offer great opportunities for camping. Nearby campgrounds include:

Sun River Facts

  • The Sun River is made up of the North Fork Sun River and South Fork Sun River
  • The river is about 130 miles (209 km) long
  • The river is part of the Sun River Project
  • The river flows through the Gibson Dam and the Sun River Diversion Dam
  • The Sun River is an excellent habitat for cutthroat, rainbow, and brook trout


How deep is Sun River? The depth of the Sun River varies from point to point. The upper section of the river is shallow compared to the deep sections at Gibson Dam, the Sun River Diversion Dam, and the Sun River Canyon.

How long is Sun River? The Sun River is about 130 miles (209 km) long.

How wide is the Sun River? The Sun River’s width varies from section to section. Below the Sun River Diversion Dam, the river is narrow as it passes through the Sun River Canyon.

Where does the Sun River start? The Sun River’s headwaters are at the confluence of the South Fork with the North Fork Sun Rivers in the Flathead National Forest.

Where does the Sun River end? The Sun River ends at its confluence with the Missouri River.

Which way does the Sun River flow? From its headwaters, the Sun River flows east, southeast, and east towards the Missouri River.

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About The Author

Will Beck

Will is a true digital nomad, taking his work on the road at every opportunity. His first love is coffee, with travel a close 2nd. He loves nothing more than hitting the road in his self-build campervan and visiting off-the-beaten-path places, away from popular tourist destinations.

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