Henry's Fork Fishing Report - September 11, 2025

Henry’s Fork Streamflows

Island Park Dam:  425 cfs

Ashton Dam:  1060 cfs

St. Anthony:  1030 cfs

Fall River:  365 cfs

Fishing has been improving on the Henry’s Fork throughout the system.  Turbidity is better than it has been for the past two months and flows are now much lower.  Clarity has improved overall due to the lower volume of reservoir water in the river, allowing for greater dilution with the clear waters of the Buffalo River and other spring influences now making up a larger overall percentage of total flow.  Dry fly anglers will find a few more targets in the slow water reaches, while nymphing and streamer anglers will still find solid game in the faster moving sections.  Cloudy and cooler weather conditions are the most desirable, but sunny days will have their opportunities as well, fall on the Fork is underway.

Box Canyon

At current flows, and likely for the rest of the season, the Box is going to be both a bumpy ride and a good place to spend a day’s trout fishing.  A check on turbidity at the dam should precede any full day’s commitment, but anything 10 NTUs and under should go well.  With the decrease in flows out of the reservoir, the clear water of the Buffalo river will do a better job of dilution as anglers get downstream of the confluence as it now makes up a larger percentage of total flow.  Indicator rigs will provide the most action, but dry/dropper rigs will be effective as well.  Streamers are an option as well, especially during periods of lower light.  Weeds are an issue, so check your flies frequently for hitchikers and choose your rig to keep your flies from hanging up on every cast.  Larger flies will still work, but they’ll catch and hold more weeds than smaller flies.  For nymphs:  PTs, R/L Tactical PTs, Split Case PMDs, red and brown Zebra Midges and Rednecks #14-18, black Zebra Midges #18-20, HP Caddis Pupa and Hare/Copper SH #14-18, Rubberlegs #8-12 and SJWs #12-14.  Streamers:  black BSA Boufaces, Olive and Copper Zonkers will generate some interest.

Railroad Ranch

The Ranch has seen a slight uptick in activity with the arrival of some mahogany duns and cooler weather.  Partly cloudy days will be better than sunny ones, but it’s worth a walk with your favorite fly rod these days.  Anglers should be prepared with a variety of offerings:  a variety of small spinners reflective of Tricos, PMDs, Baetis, and Pseudos #16-22; emergent PMDs like the Heames Klinkhammer, Harrop’s Captive Dun, and Lawson’s Halfback PMD.  Terrestrials should include hoppers, small flying ants, and honey ants, all are present in good numbers.  For mahoganies, we like the CDC Thorax Dun, CDC Biot Dun, Captive Dun, and a naked PT.

Canyon Country

The canyons of the Henry’s Fork have been fishing well and will will remain fishable for the next couple of weeks, these sections are great places to spend a day in periods of fair weather.  Low flows make the pockets more readable and accessible to flies, they also make for a longer float, so plan accordingly and bring extra water, layers, and some food!  Dry/droppers are our preferred rigs, a high viz Chubby Chernobyl with a Rubberlegs hanging below is a good place to start.  Larger beadhead nymphs #12-14 are a good choice as well if pickings are slim.  Streamers are a good option in here, we like a heavy fly on a floating line with 1X as tippet.  Having an indicator nymphing rig will come in handy to work the water more thoroughly when stopping and pulling over.

Warm River to Ashton

As the most consistently fishing stretch of the Henry’s Fork, this piece of water will be a good choice on most days for anglers looking for good action on small to mid-sized trout.  Dry/droppers, indicator nymphing rigs, and streamers will all produce results, so anglers can fish their preference and find some positive feedback.  Browns are on the move and a little more territorial than they were a couple of weeks ago, they can show up anywhere in the system, be prepared for a surprise if a big one ends up on the end of your line!  Refer to the Box Canyon recommendations for useful flies in here.

Below Ashton Dam

With fair weather, the lower river will reward persistent anglers in the mornings more than the afternoons.  Dry/dropper rigs and streamers are the most consistent methods currently.  Ditching the dropper and floating a hopper or other terrestrial can be a liberating experience and one worth trying.  We expect to see a slow ramping up of these lower sections over the course of the month as cooler weather becomes the norm, but good game will be found for those who look for it.  Nymphs should be reflective of small stoneflies #10-12, midges #18-20 and smaller mayflies #16-20.

Good luck out there!