Flathead River

The main-stem Flathead is the big river everything upstream drains into. The North and Middle Forks meet at Blankenship Bridge, the South Fork ties in just above Columbia Falls, and from there the river runs wide, deep, and glacially clear through the Flathead Valley into Flathead Lake — then continues below the lake out of SKQ (Kerr) Dam near Polson. It's one of the last strongholds of pure-strain wild westslope cutthroat, and it's core bull trout water too (ESA-listed, do-not-target, mandatory release). What sets it apart from the classic southwest Montana rivers is that it fishes as a native-cutthroat dry-fly float, not a rainbow/brown tailwater — you search gin-clear water with attractor dries for eager cutthroat rather than matching a technical hatch.

Practically, it's a drift-boat river. The upper main stem from Blankenship down to Old Steel Bridge is the trout heart of it — wide, frequently deep, steady current with a few small rapids below Blankenship; wading is tough except in late-summer low water. Prime time is July through September once runoff clears, and it fishes dry or dry-dropper almost all summer: Chubby Chernobyls, Amy's Ants, and elk hair caddis up top with a pheasant tail or small nymph off the back. Early season it can push 15,000-20,000 CFS on snowmelt out of Glacier country and blows out; it drops into shape by early-to-mid July most years. The Columbia Falls gauge (USGS 12363000) is the number everyone watches — roughly 4,000-8,000 CFS fishes well for the float, dropping toward 3,000-5,000 by late summer.

The context below Kalispell is different water. The river slows into sloughs and warms, turning into northern pike country more than a trout float as it approaches Flathead Lake. Below the lake, the lower Flathead runs out of SKQ (Kerr) Dam through the Flathead Indian Reservation — completely flow-regulated for power, trophy pike water with some rainbows in the first few miles below the dam, and it requires a CSKT tribal permit (about $10 for three days or $17 a year), not a Montana license. Note the 2024-25 regulation change: the single-hook restriction (no treble or double hooks) now extends down the main stem all the way to Flathead Lake.