Henry's Fork Fishing Report - May 21, 2026
Henry’s Fork Streamflows
Island Park Dam: 636 cfs
Ashton Dam: 1210 cfs
St. Anthony: 801 cfs
Fall River: 590 cfs
With so much information available to us these days, today’s average angler comes into the beginning of the season better prepared in terms of what to expect based on snowpack conditions, water forecasts, and seasonal outlooks than anglers of a decade or more ago. However, these logs of information often lack the context that helps us understand just how fishing is going to be for any given week on the horizon. While it’s certainly true that this is an incredibly dry year in the Western United States, and that many of our western trout fisheries will experience challenging flows and fishing conditions, the outlook today for tomorrow and the coming weeks is a good one. We still have snow in the mountains, our grass is only recently become green in the high country, and the usual mix of unpredictable weather is present. Despite a warmer than average April and May, we still woke up to snow on the ground only a few days ago, which was predictable in its own way only because there were salmonflies hatching on the Henry’s Fork at that very moment! Conditions are low for the date throughout the river, but water temps are cold, water quality and good shape and hungry trout are found from top to bottom. Watch for rising flows throughout this week as irrigation demand from downstream is already calling for water from Island Park Reservoir.
Box Canyon
The Box is in great shape and at current flows it’s starting to come into a comfortable flow for navigation and fishing. It has been low in here for the past months, so don’t expect an even distribution of trout throughout the canyon, shallow areas were extremely shallow only a week ago, and will take some time to populate with larger trout. Indicator nymph rigs will be the most productive here most days, but we expect to see salmonflies flying around over this next week, there are some in there already and they’ll be more active on sunny days than cold and cloudy ones. With big bugs around, it’s always worth a short float through the canyon during periods of warm weather, and just as easy to spend an entire day in there working the water more thoroughly. For indicator nymphing rigs, a B shot should suffice if you’re not throwing heavy flies, and occasionally a BB may be useful. For flies, we recommend the HF Salmonfly, JoJo’s Salmonfly, Razorback Salmonfly and the Fluttering Stone in sizes 4-6. Other than stonefly nymphs, both golden and dark in sizes #6-8, nymphs should be smallish, sizes #14-18. We like to have a mix of red Zebra Midges, PMD Frenchies, BWO Frenchies, PTs, R/L Tactical PTs, Hare/Coppers, tan HP Caddis Pupa, and your favorite perdigons. Jig Napoleons, Bullet Quills, Spanish Bullets, and Olive Hot Spots will all do the trick.
Railroad Ranch
Closed until June 15th
Canyon Country
The canyons of the Henry’s Fork are in good shape and full of stoneflies at the moment, lots of nymphs around and some adults flying around in decent numbers. Most days will be good days to be in here for some good, old fashioned dry-dropper adventure fishing. It’s pretty hard to beat a “Chubberlegs” rig in here at any time of year (Chubby Chernoby with a Rubberlegs dropper), but this time of year it’s mandatory equipment! If stoneflies aren’t getting much attention, try a fast sinking dropper in a mayfly profile, size #12-14 for a little more action. Streamers can be fun as well. Remember that a raft and solid oarsmanship are a must in these sections and to pack extra layers for anything that mother nature might throw out at you!
Warm River to Ashton
Anglers have been enjoying some fun fishing down here, with a few salmonflies and golden stones still around, as well as plenty of caddis. Colder days will see some baetis as well. This is a good time of year to go full send with a dry fly, hedge your bets with a dry/dropper, or stick with the indicator nymphing rig for the most consistent results. Better yet, mix it up throughout the day based on what you’re seeing and what’s working! Fly selections will be about the same as those for the Box Canyon, but add in some black leeches and maybe a few streamers as well! This is a good time of year to find a larger trout in this reach of the river.
Below Ashton Reservoir
The lower Henry’s Fork is a dynamic place to be at the moment and anglers should keep a close eye on flows as they will be increasing out of Ashton Dam this week. Fall River still has some snowmelt to go, but not a ton. Cooler weather will drop flows out of the Fall River and warmer periods will see it coming up, this will directly affect the river below the Chester Dam. Anglers should be ready to encounter stoneflies anywhere on the lower river below the Falls, but the opportunities will come and go quickly. Above the Chester Dam, Salmonflies have come and gone, but keep an eye out for bursts of Golden Stones. Caddis will be the main driver of the bite in here, with PMDs coming into play by the end of the month. Anglers should be ready with Golden Stone imitations to fish alone or with dry/dropper rigs and be prepared to indicator nymph when necessary. Nymph selections should be similar to what we’ve recommended for the Box Canyon, but be sure to have those Hare/Coppers, HP Caddis Pupa, and maybe some Lightning Bugs in there along with a variety of sizes of PTs and Rubberlegs nymphs.
Good luck out there!!
