Henry's Fork Fishing Report - September 10, 2026
Henry’s Fork Streamflows
Island Park Dam: 1170 cfs
Ashton Dam: 1640 cfs
St. Anthony: 1700 cfs
Fall River: 371 cfs
In Henry’s Fork country we are now beginning to feel the reality of the depth of this year’s low water quantity. Though there are sections that are fishing well and will continue to do so in the coming weeks, anglers should expect changes in conditions and stay abreast of flows and turbidity by checking the Henry’s Fork Foundation’s water quality site, especially in the upper river. Increasing turbidity in the water from Island Park Reservoir should be expected as this week progresses, affecting the Box Canyon and the Ranch, primarily.
Box Canyon
The Box is at the front of the line when it comes to dealing with low water clarity from Island Park Dam and fishing has been slowing down in there as visibility becomes more limited. We expect this to continue along the same trend as this week progresses, making fishing more difficult in here in the coming days and weeks. For the time being, anglers venturing in should consider using higher visibility flies with fluorescent hot spots and others in larger sizes. Streamers can be effective in water conditions such as these, but generally fishing will be slower in here than in the past weeks.
Railroad Ranch
Changing conditions, both in weather and in water quality are keeping anglers on their feet in here. Cloudy days will be better than sunny ones and keeping an eye on turbidity readings at the Pinehaven site can give a good idea as to how water conditions are shaping up. Baetis, Mahoganies, PMDs, flying ants, hoppers, callibaetis, and small spinners are all on the menu here, rising fish are not aplenty so anglers should plan on working to find suitable targets and bring their A games. Good flies to make sure you have in your boxes are: Sparkle Flag Dun #16-18; CDC Thorax Mahogany, CDC Biot Mahogany, Tilt Wing Dun Mahogany #14-16, LC Cripple PMD #16, Heames and Harrop’s Honey Ants #16-18, Shimazaki Black Ants #16, Copenhaver Spinners #16-20, naked PTs #14-18.
Canyon Country
The canyons are among the more resilient sections when turbidity is spiking in the upper river; these sections allow for settling to occur and typically remain fishable when things aren’t upstream. We expect this to be the case in the coming week as well, with dry/dropper rigs being the most common in here. High viz dry flies with some sort of stonefly dropped below will usually do the trick, but be sure to bring along a good selection of fast-sinking beadheads as well if trout are finicky. Streamers can be a good choice as well!
Warm River to Ashton
This section continues to offer decent action on small to medium-sized trout and remains a good choice for beginning anglers or those wanting to “knock the rust off”. Larger trout can be targeted with streamers and large dry flies, but with less consistency. There are brown trout on the move in here, now is a great time to play with different sink tips and streamers in search of a larger tug. For flies we like rubberlegs #8-12; Hare/Copper, PTs, Split Cases, brown Zebra Midges and HP Caddis #14-18. Your favorite perdigons will work as well, but we especially like Duracells, Olive Hot Spots, Black Daggers, and Napoleon Jigs #14-18. For streamers, let your imagination run wild, a variety of offerings will work.
Below Ashton Dam
The lower river has been fishing better and better as water temps cool down. Cloudy days will be better than sunny ones, and better action will be found by fishing subsurface these days. Indicator rigs as well as dry/droppers are producing results at the moment, with streamers working in the wee hours or on cloudy days. Keep an eye out for baetis hatching when there are clouds in the sky and rising trout during these times.
Good luck out there!
