Fly Fishing Musselshell River - Martinsdale

The Musselshell River near Martinsdale is one of Montana's most underrated fly fishing destinations, offering an exceptional brown trout fishery in the rolling foothills of central Montana where the Castle Mountains, Crazy Mountains, and Little Belt Mountains converge. Flowing approximately 30 miles from the confluence of its North and South Forks near Martinsdale downstream to the Highway 191 Bridge at Harlowton, this upper section contains the river's prime trout water, with brown trout comprising an remarkable 96% of the total trout population according to Montana FWP electrofishing surveys. Featured in Fly Fisherman magazine as one of Montana's rivers "that don't have overflowing parking lots or unending flotillas," the Musselshell offers genuine solitude and excellent fishing for anglers willing to explore beyond the state's famous destination waters.

The Musselshell has a spring creek character despite being technically a freestone river — narrow (typically less than 30 feet wide), clear, with twisty meanders, undercut banks, and shallow riffles that demand careful approaches and technical presentations. The river bottom consists of gravel, cobble, and silt, with overhanging willows and grass banks providing essential cover for the resident brown trout. The gradient is gentle through the agricultural valley, creating a mix of undercut bank pools, riffles, and slow-moving runs. Water clarity is typically excellent when flows are stable, though irrigation diversions can significantly impact summer flows, dropping them below 50 CFS in dry years. The surrounding landscape of open grasslands, hay meadows, and distant mountain ranges creates a distinctly different Montana fishing experience from the forested mountain streams of the western part of the state.

This section supports an extraordinarily high percentage of wild brown trout — approximately 96% of the trout population — with electrofishing surveys recording densities ranging from 156 to 910 brown trout per mile depending on conditions. Fish typically range from 12 to 16 inches, with 14-16 inch browns being the most common catch on a typical day of 4-8 fish. Trophy brown trout exceeding 18-22 inches are realistic targets for skilled anglers, with occasional fish approaching 25 inches and 5 pounds. Mountain whitefish provide consistent action, while rainbow trout, brook trout, and native cutthroat trout are present in minor numbers. Below Harlowton, water temperatures become too warm for productive trout habitat and the river transitions to warmwater species.

Hatch activity follows a pattern suited to the river's spring creek character, with Blue-winged Olives providing major hatches in spring (March through May) and fall (September through October) that can produce excellent technical dry fly fishing on overcast days. Caddis hatches emerge from May through July, providing consistent opportunities, and PMDs appear when mid-summer flows cooperate. Stoneflies are present but smaller species that don't define the fishery. Terrestrial fishing is a signature of the Musselshell — as summer progresses and flows drop, hopper fishing becomes outstanding, with grasshoppers, ants, and beetles producing aggressive surface takes along the grassy banks. Streamer fishing is particularly productive for trophy browns in the early season (March through June) and again in fall (October and November) when pre-spawn aggression peaks. Midges provide consistent year-round subsurface opportunities.

The Musselshell is overwhelmingly a wading-only fishery. The river is easy to wade — typically shallow and less than 30 feet wide — but the spring creek character demands a stealthy, careful approach with undercut banks, bushy banks, and clear water requiring presentations that won't spook educated brown trout. Floating is not practical due to diversion dams requiring portages, fences across the river, slow water, frequent wind, and summer low flows. Access is the biggest challenge — the river flows predominantly through private ranch land with limited public access. Selkirk Fishing Access Site west of Two Dot is the primary public access with cottonwood shade and undesignated camping sites. Additional access exists at Two Dot Road Access and the Highway 191 Bridge at Harlowton. Montana's stream access law allows wading below the high-water mark, but legal access to the river requires using designated access points. Guided trips on private water provide access to miles of otherwise inaccessible fishing through outfitters like Montana Angler. Nearby services are available in Martinsdale, White Sulphur Springs (25 miles west), and Harlowton (30 miles east). The nearest major commercial airport is Bozeman Yellowstone International (BZN), approximately 97 miles southwest.

The Musselshell River near Martinsdale is a hidden gem of central Montana fly fishing, offering an intimate, technical brown trout fishery that rewards the angler who appreciates solitude, stealth, and the satisfaction of fooling educated fish in spring creek conditions. Its 96% brown trout composition, trophy potential, and complete absence of crowds make it an ideal destination for experienced anglers seeking something genuinely different from Montana's famous blue-ribbon waters.