Smallmouth bass are the only warmwater fish on this site, and they are here because two rivers we cover, the John Day in Oregon and the San Juan through Utah's canyon, turn into smallmouth water when they warm past what trout can stand. That is the whole story of Western smallmouth in a sentence. Micropterus dolomieu is native to the Great Lakes, the Ohio and upper Mississippi drainages and the rivers of the Appalachian foothills, and it was carried West in the late 1800s, where it found rocky, warm, low-gradient river miles that no trout wanted and made them its own.
Where in the West they are a real fishery
GBIF records place smallmouth in Oregon, Wyoming, California, New Mexico, Idaho, Washington, Colorado, Montana, Arizona, Utah and Nevada among Western states, but records and fisheries are different things. The Western rivers where smallmouth are genuinely worth a trip share a profile: big, rocky, warm by summer, and at low elevation. The John Day is the best example on this site, a wild desert canyon river that is a trout and steelhead fishery in its upper reaches and cold months and a smallmouth river through its lower canyon all summer. The Columbia and lower Snake, the mainstem Umpqua in Oregon, and the lower Yakima in Washington are the same kind of water. In the Southwest the lower San Juan below the trout reaches and the big canyon reservoirs, Flaming Gorge among them, hold strong populations. The Oregon, Washington and Utah bass hubs list every water in each state with recorded smallmouth.
Smallmouth are not native anywhere in the West, and in some drainages they are a problem for native fish, eating juvenile salmon and steelhead in the Columbia system and native minnows and suckers in the Southwest. Several agencies have removed limits on them for that reason. It does not make them less fun to catch.
The two rivers on this site
- John Day River, Oregon: smallmouth in the lower, warmer sections, good on poppers and streamers in summer. The Service Creek to Clarno float runs seventy-plus miles through the canyon and is the classic multi-day smallmouth trip in the Northwest, with redband rainbows in the cold months.
- San Juan River, Utah canyon: smallmouth increasingly dominant in the lower canyon, taking poppers and streamers in summer once water temperatures push the trout to cold refuges. The Sand Island to Mexican Hat float near Bluff is the standard trip.
On Flaming Gorge, the page points to the Sheep Creek canyon arm as the best smallmouth fly water on the reservoir, fished at dawn with poppers along the sandstone ledges.
How river smallmouth hold and feed
A river smallmouth is a structure fish. It holds on and around rock: the downstream side of boulders, ledge drop-offs, the seams where a rocky riffle spills into a pool, the deep edges of gravel bars, and any place current brings food past a hard edge. It eats crayfish above everything else, then minnows and sculpins, then whatever falls in. Unlike a trout it will move a long way for a fly, chase it, and hit it on the surface in broad daylight if the water is warm enough. The key variable is temperature. Below the mid-fifties smallmouth are sluggish and deep; from the sixties into the seventies they feed hard and will come up for a popper; on the hottest afternoons they slide into the deeper, shaded rock and feed at dawn and dusk. In the West this makes summer, June into September, the season, which is exactly when the trout rivers are at their worst.
Fly tactics that work
A 6- or 7-weight rod, a floating line for surface and shallow work and an intermediate or sink-tip for the deep ledges, and a short leader of 0x to 2x. The flies the river pages here name are the whole box: Clouser Minnow in 4 to 6, Woolly Bugger in 4 to 8, poppers in 2 to 4, and a crayfish pattern in 4 to 6.
Start on top when the water is warm. A popper or a foam slider cast tight to a rock ledge, left to sit until the rings disappear, then popped once and left again, draws smallmouth from surprising distances. If they follow and refuse, go to a Clouser or a Bugger and swing it along the drop-off, stripping in short, sharp pulls with pauses; smallmouth take on the pause. When the fish are deep in midday heat, the crayfish pattern crawled along the bottom on a sinking line, with a slow lift-and-drop, is the fly that keeps working. Fish the rocks, not the sand. A hundred yards of ledge and boulder is worth a mile of flat gravel.
Smallmouth hit hard and jump, and a two-pound river fish on a 6-weight pulls like a much bigger trout. Set with a strip strike rather than lifting the rod, especially on a popper, since a lifted rod pulls the fly out of a fish that has not closed on it yet.
Floating for smallmouth
Both site rivers are float fisheries in their smallmouth reaches, and a raft or drift boat is the way to fish them. Cover water: cast to every rock as it comes, work the eddies behind boulders, and stop to wade the good ledges. Bring more water and sun protection than you think a river trip needs, since the canyons that hold smallmouth are hot by design. The John Day and the Utah San Juan are both low-flow rivers in summer, so watch the USGS gauge on each page and check with the BLM about launch conditions.
What to check before you go
Bass limits, or the absence of them, gear rules and float permits vary by river and change. Oregon's, Utah's and the other state agencies publish the current rules for each water, and the BLM manages the launches on both floats above. Check both, then pick a hot week in July and go fish the rocks.