Best Smallmouth Bass Rivers in Montana for Fly Fishing

The Clark Fork is Montana's largest river by volume and its premier smallmouth bass destination — a powerful, clear river that cuts through a dramatic canyon west of Missoula before flowing into Idaho. The prime smallmouth water runs through the Clark Fork Canyon from Superior downstream through Plains and Paradise, where the river narrows around bedrock outcroppings and boulder fields that create ideal bass habitat. Smallmouth in the 11–16 inch range are common in this stretch, with the rocky riffle-pool structure supporting healthy populations through the canyon corridor.

Clouser Minnows in white/chartreuse are the Clark Fork's most productive patterns, particularly effective stripped through the deeper runs and current seams along the canyon walls. Evening popper fishing on the flatter pool sections produces explosive surface action from late June through August — position yourself downstream of a riffle and work a foam popper along the shade line as the canyon walls block direct sunlight. The river parallels Highway 135 west of Missoula through much of the canyon, with numerous pullouts providing convenient wade access to excellent water.

Float fishing by canoe or kayak unlocks the most remote and productive Clark Fork Canyon sections between Superior and Plains. The river's gradient provides good current throughout the season, keeping flows reliable even during dry Montana summers. A half-day float between bridge access points covers productive water that sees very little angling pressure compared to the river's upstream trout sections near Missoula.

The lower Yellowstone River — from Billings east through Miles City and Sidney to the North Dakota border — is eastern Montana's premier smallmouth bass river, and one of the most overlooked warmwater fisheries in the northern Rockies. This braided prairie river holds smallmouth in the 12–17 inch range across miles of gravel bars, cutbank channels, and rocky shoals that see a fraction of the angling pressure of the Yellowstone's famous upstream trout water. The sheer scale of the lower river means productive water is always available even on busy summer weekends.

Crawdad patterns are the lower Yellowstone's most productive flies — the river's gravel substrate supports an abundant crayfish population that smallmouth key on through the summer months. Clouser Minnows cover the deeper mid-river channels and current seams. Float the lower Yellowstone by canoe or drift boat from Miles City to Glendive for access to the most remote and productive stretches. A 6-weight handles average fish well; bring a 7-weight if the characteristic eastern Montana wind picks up — exposed prairie reaches can make casting demanding.

The Bighorn River below Yellowtail Dam is world-famous for trophy trout, but the lower Bighorn — below the quality trout water near Hardin — transitions into classic warm-water habitat where smallmouth bass become the primary game fish. This overlooked stretch flows through open Crow Agency land with minimal angling pressure, offering excellent smallmouth fishing in a strikingly different Montana landscape than the upper Bighorn's dramatic canyon. Fish the lower river for a genuine off-the-beaten-path experience in a state where smallmouth remain well under the radar.

Woolly Buggers in black or olive strip effectively through the Bighorn's lower runs, while foam poppers produce exciting evening surface action in the flatter pool sections. Water flows on the lower Bighorn are regulated by Yellowtail Dam, providing consistent summer levels that benefit both access and fish activity. Float from Fort Smith downstream and plan your trip for early to mid-summer before the Bighorn's characteristic low-water conditions concentrate fish in fewer pools.