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South Fork of the Flathead River


The South Fork of the Flathead River is a major river in Northwestern Montana. It is one of the three main forks of the Flathead River, a tributary of the Clark Fork River. This north-northwest trending river is about 98 miles (158 km) long, making it the second longest tributary of the Flathead River.

This river begins in the Bob Marshall Wilderness south of Glacier National Park, at the confluence of two streams, Danaher Creek and Young’s Creek, between the Flathead Mountain Range and the Swan Mountain Range. For some 40 miles (64 km), the river flows freely north-northwest, meandering through a forested and undeveloped valley. The river enters a narrow gorge, running north, then begins to enter the backwater of Hungry Horse Reservoir after receiving Meadow Creek from the left. Hungry Horse Reservoir occupies much of the lower half of the river, covering 97 square miles (250 km2). The reservoir trends north then northwest, and the river then passes through the arched Hungry Horse Dam, just a few miles above the mouth. After it leaves the dam, the river enters a narrow gorge and, exiting the canyon for the final time, runs northwest past the town of Hungry Horse, then joins the Main Stem of the Flathead River.

The South Fork of the Flathead River is home to native Westslope cutthroat trout and bull trout. The South Fork of the Flathead River is one of the few places in the Lower 48 where it is legal to target bull trout. The bull trout is a threatened species and can reach 40 inches long. Many experienced anglers highly regard the bull trout and consider it a “bucket list” species. Westslope cutthroat trout are plentiful in the South Fork of the Flathead River and are eager to hit a dry fly. The Westslope cutthroat trout often hit dry flies with reckless abandon and are the perfect trout for beginner fly anglers to target.

The South Fork of the Flathead River is stunning in its beauty. Don’t forget your camera on this adventure. The memories you take home will be cherished for a lifetime. Access is difficult on the South Fork of the Flathead River. Montana Fly Fishing Experience guides are the some of the most experienced boatmen on this beautiful stretch of river.

Hatches on the South Fork of the Flathead River include caddis, mayflies, spruce moths, and many terrestrials including hoppers, ants, and beetles. Depending on the time of year, anglers could be throwing large foam flies, deer hair caddis flies, or tiny emerging mayflies. The bull trout in the South Fork of the Flathead River are primarily meat eaters. Large streamers are typically in order when targeting the bull trout.

98 miles (158 km)

Average rate:
3,483 cu ft/s (98.6 m3/s)

Basin features
River system
Columbia River

Basin size
1,663 sq mi (4,310 km2)

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