Montana's two great tailwaters, the Bighorn and the Missouri, fish twelve months a year on midges, scuds and Blue-Winged Olives, while its freestones pack the whole season into the four months after runoff. That split is the first thing to understand about planning a trip here. The eleven rivers below are the ones on this site, grouped by region: the tailwaters, the southwest freestones out of Bozeman and Ennis, the Missoula-country rivers, and one wilderness cutthroat river you need a pack trip to reach.
The two big tailwaters
Bighorn River, Montana
Below Yellowtail Dam at Fort Smith, the Bighorn holds one of the densest trout populations in Montana. The Afterbay ramp to the 13-Mile access is the standard float; below that the river runs through the Crow Reservation and needs a tribal permit. Sow bugs and scuds work all year, midges and Blue-Winged Olives from October through April, PMDs in June and July, and a Trico spinner fall from July into September that starts at dawn. Browns get large here and hit streamers in fall.
Missouri River, Montana
The Missouri below Holter Dam, from Craig down to Cascade, is a tailwater the size of a big river that fishes like a spring creek. Wade access from the public sites on both banks means you do not need a boat. The Trico falls of July through September are the famous event and require being on the water before seven; the fall Blue-Winged Olive fishing for browns is the quieter one. Craig is the hub; the water nearest Holter Dam is more technical and denser with fish.
Southwest Montana freestones
Madison River, Montana
The fifty-mile riffle between Quake Lake and Ennis, Blue Ribbon water with FWP access sites along US-287, is the center of Montana fly fishing. The Salmonfly hatch in June moves upstream at several miles a day, so the peak on any one stretch lasts only a few days; after it come Golden Stones, caddis, PMDs, Tricos in August and September, then crane flies and hoppers. The lower river below Ennis is drift boat water with the state's most aggressive fall browns.
Big Hole River, Montana
The Big Hole is the last river in the lower 48 with wild fluvial Arctic grayling, found in the upper valley near Wisdom along Highway 43. Melrose is the hub for float trips on the brown and rainbow water in the middle river, where the June and July Salmonflies bring the crowds. Twin Bridges at the bottom is bigger water with fall streamer fishing near the Jefferson confluence.
Gallatin River, Montana
US-191 follows the Gallatin from Big Sky to the Yellowstone boundary with pull-offs every few hundred yards, which makes it Montana's easiest river to fish without a plan. Rainbows in the canyon pocket water take attractor dries all summer; browns take over below the canyon in the valley toward Three Forks. Salmonflies in June, caddis through August, hoppers in July and August.
Yellowstone River, Montana
The Yellowstone through Paradise Valley is the longest undammed river in the lower 48, with FWP access sites between Yankee Jim Canyon and Livingston for both wading and floating. Yellowstone cutthroat near Gardiner, rainbows through the valley, browns below Livingston. The Salmonfly hatch starts at Livingston in late May and reaches Gardiner by mid-June; hoppers run from July into September, and October is for streamers.
Missoula's home rivers
Blackfoot River, Montana
The Blackfoot is the river from A River Runs Through It, restored from decades of mining damage into a genuine fishery. Ovando is the gateway to the upper valley's riffle-pool Salmonfly water; Highway 200 reaches the mid-river access sites with the most consistent fishing; Bonner near the Clark Fork confluence is bigger water for fall streamers. Westslope cutthroat are recovering in the upper reaches and should go back in the water quickly.
Bitterroot River, Montana
The Bitterroot valley from Darby down to Missoula is reached from US-93 and county roads with plenty of fishing access sites. The Salmonfly hatch starts near Missoula and moves upstream over three or four weeks, so fish it near town first and follow it south. Rainbows dominate, browns are increasing near the Clark Fork confluence, and the hopper fishing from July into September is as good as anywhere in the state.
Clark Fork River, Montana
The Clark Fork runs through downtown Missoula, with access at Caras Park, Bess Reed Park and Greenough Park, and it holds wild trout within a walk of the hotels. Above town at Bearmouth and below toward Superior there is float and wade access with less pressure. The Milltown Dam removal reconnected the river and its cutthroat; Salmonflies in June, caddis through August and hoppers in late summer are the fishing.
Rock Creek, Montana
Rock Creek is a wilderness freestone off I-90 at Clinton, with Rock Creek Road running up the canyon past USFS campgrounds. Westslope cutthroat are the signature fish and they eat attractor dries; the Salmonfly hatch in May and June is early by Montana standards. The first five miles are the busiest, the campground stretch ten to twenty miles up is the sweet spot, and beyond thirty miles the pressure is close to zero.
Wilderness cutthroat
Flathead River — South Fork, Montana
The South Fork of the Flathead flows through the Bob Marshall Wilderness, and the fishing gets better the farther you are from a road. Spotted Bear Ranger Station south of Hungry Horse is the practical entry, often by horseback; the Benchmark trailhead is a forty-plus-mile multi-day approach to the upper river. Westslope cutthroat take attractor dries through the July and August stonefly, caddis and hopper season. Bull trout are present and protected; release them immediately.
Planning around Montana's runoff
Freestone runoff typically peaks in late May or early June and the rivers clear over the following two to three weeks; the Salmonflies arrive as they do. Before that, fish the Bighorn and Missouri, or the Madison and Yellowstone on spring Blue-Winged Olives in March and April. From late June through September everything is in play, and October is the streamer month for browns statewide. Montana FWP maintains the fishing access sites and sets section-specific regulations, including seasonal closures and hoot-owl restrictions in hot summers; check current rules before you go. Tribal and Yellowstone National Park water carry their own permits.