Fly Fishing Bighorn River - Thermopolis

Fly fishing Bighorn River – Thermopolis (Wedding of the Waters to Skelton) begins at one of central Wyoming's more evocative spots — the Wedding of the Waters, a few miles south of town, where the Wind River spills out of Wind River Canyon and changes its name. From there the Bighorn swings north past Kirby and Lucerne to the Skelton Public Access Area, roughly fourteen miles of Blue Ribbon trout water at about 4,300 feet. This is open, sun-washed meadow country rather than timbered canyon, with US 20 alongside the corridor the whole way and Thermopolis, hot springs and all, sitting on the river a few miles below the top of the reach.

This is a true tailwater, and everything about how it fishes traces back to Boysen Dam. Bottom releases from Boysen Reservoir drop sediment behind the dam and buffer temperature, so the Bighorn below Wedding of the Waters stays cold and clear while Wyoming's freestone rivers are running the color of chocolate milk. The gradient is gentle, only a few feet per mile, which gives the reach a flat-water personality: long glassy runs, broad riffles that tail into deep green pools, soft inside seams, and side channels that peel off around gravel bars. Stable flows build a stable food base, and this stretch is genuinely biomass-rich — scuds, midge larvae, and aquatic worms carpet the bottom year-round.

Three trout species share this water at once. Brown trout, rainbow trout, and Snake River cutthroat trout all hold here, and a Snake River cutthroat brought to hand is a fine bonus on a river better known for its browns. Mountain whitefish are abundant throughout and will keep a nymph rig honest all day. Most trout run 14 to 18 inches, thick-shouldered from the rich tailwater diet, with browns that go considerably larger.

Bugs come off here in every season. Midges are the one constant, hatching year-round and carrying the cold-weather fishing on small pupae and, when clouds settle in, tiny adults on top. Blue-winged olives are the mayfly this reach is known for, arriving in a spring push and again in fall, and a gray, spitting day is when they show best. Caddis take over through the warm months, pale morning duns give you a midday look at rising fish across summer, and Trico spinner falls stack up in the mornings from midsummer into fall — small flies, fine tippet, and fish that refuse a sloppy drift. Once the grassy banks warm, hoppers and ants pull trout tight to the edges. When nothing is showing on top, scuds, midge larvae, and worm patterns keep the day honest.

Flows are dam-driven rather than snow-driven. The reach fishes best somewhere in the 800 to 2,000 cfs range and stays floatable up to about 3,500. The reference gage sits at Boysen Dam, about fourteen river miles above the top of the reach with no major uncontrolled tributary in between, so it reads the same regulated water this stretch sees, just with a short lag. Wading is easy by Wyoming standards thanks to the low gradient, though the clarity that makes this river a pleasure also makes the trout spooky. Floating is the better way to cover the whole reach.

Access is simple and public at the key points. Wedding of the Waters, about five miles south of Thermopolis, anchors the top with a boat ramp. Kirby Ditch Public Access Area, roughly four miles north of town, gives you parking and a ramp mid-reach, and Skelton Public Access Area about nine miles north marks the downstream end. The Eighth Street bridge ramp in town adds another option, and fly shops, shuttles, lodging, and the hot springs are all right there.