Henry's Fork Report - July 31, 2025

Henry’s Fork Streamflows (USGS)

Island Park Dam:  711 cfs

Ashton Dam:  1440 cfs

St. Anthony:  898 cfs

Fall River:  290 cfs

July and all that comes with it nears sunset for the 2025 season and we are welcoming what August may bring this year.  Though plenty of good fishing has been had on certain reaches of the Fork this last month, the fabled Railroad Ranch has been pretty quiet.  The high flows of irrigation season are settling down into the lower flows of late summer and fall.  Water temps are staying below 70 degrees in all stretches but the very lowest from St. Anthony and below.  Dissolved oxygen looks excellent throughout the river so far, our trout are pretty well rested and in great shape, once they start looking to the surface in earnest we are looking forward to some great dry fly fishing.  Turbidity is currently the variable to watch, with Island Park Reservoir just under half-full, algae blooms and fine sediment coming in from the very shallow west end, the big pool is starting to look a little soupy.  Flows out of Island Park Dam at the top of the Box Canyon are where things are the worst, and the river becomes more fishable about a mile down from the top, and by the time the river reaches Pinehaven, clarity is generally not a factor anymore.  Keep an eye on the Henry’s Fork Foundation’s “Water Quality” tab on their website to be aware of spikes in turbidity.  A weedy river is the norm in August, especially as flows continue to drop, be prepared to deal with them in certain sections.

Box Canyon

Though the water at the top of the canyon may resemble split pea soup at times, things improve as you drop around the corner, so to speak.  The addition of the Buffalo River helps considerably and as you move downstream, some of the major particulate begins to settle.  Fishing is good in the Box at these flows, plenty of great trout fishing to be had from here on out through the end of the season.  When the water is dirty, be prepared with flies accented with hot spots and fluorescents; when clarity improves, a turn to red and more subtle flies might be a good choice.  Indicator nymphing will be the main choice, keep your flies clean of weeds and change weight to match the depth of the water you’re fishing.  Streamer fishing can be productive as well during periods of lower light, and there are still some golden stoneflies flying around in there, so a dry fly run or dry/dropper rig are both worthy of a try.  For Dries, we like Jojo’s Golden Stone, Lawson’s HF Golden, BSA Razorback, Waterwalkers and Root Beer Chubbies #8-12.  For streamers, try an olive/black BFE, olive, white or black BSA Bouface #6, or an olive or copper Zonker #4-8.  Nymphs we are keeping on rotation in here are:  Rubberlegs #6-10, PTs, R/L Tactical PTs, Rednecks, Split Cases, HP Caddis Pupa, red and brown Zebra Midges #14-18, black Zebra Midges #18-20.  Various perdigon flies will work as well, but we like the following:  Olive Hot Spots, red Jig Napoleons, Frenchies, Spanish Bullets, Bullet Quills #14-18, and Black Daggers #16-20.

Railroad Ranch

While the Ranch is known for challenging fishing, the main challenge continues to be finding a reasonable number of targets to fish to.  High turbidity spikes don’t help anything down here, so an eye out for those quick increases is advised.  Though this past week has shown an uptick in the surfact activity, the trend is still on a slight improvement.  Opportunities should continue to improve and we think the trend will remain slight but in the right direction.  A wide variety of flies should be kept on hand, mostly with a variety of spinners, Gray Drakes, PMDs, Caddis, Callibaetis, Tricos and terrestrials including flying ants, beetles and grasshoppers.  We like to keep the following flies in our boxes at the moment:  all kinds of spinners, including Harrop’s CDC Biots and Paraspinners, Copenhavers, Barret’s in multiple colors #14-20.  HF and Partridge Caddis #14-18, PMD Transitional Duns, Harrops PMD Thorax, LC Cripple, Heames Klinkhammer PMD #14-18, Harrop’s and Heames’ Honey Ant, Shimazaki CDC Ant #14-18, and a variey of hopper patterns #6-10.  Unweighted PTs can be handy when you encounter trout feeding heavily on emergers.

Canyon Country

The canyons of the Henry’s Fork seem impervious to the troubles of clarity and water quantity just upstream.  The weeds seem to break up in the fast water and clarity is generally just fine for fishing purposes.  Lower flows make it easier to read and fish this water with dry/dropper rigs, but indicator rigs can be useful when slowing things down and working the water more carefully.  Streamer rigs can be a great choice down here as well, we always favor a quick-sinking fly on a floating line for these sections.  Lower flows make rowing a bit more technical and anglers should be always aware that afternoon weather arrives here with no advance notice, rain gear is not to be overlooked.  Solid oarsmanship and a raft are a must.

Warm River to Ashton

For anglers looking to have a fun day of fishing with more of a focus on quantity over quality, this section remains and excellent choice on most days.  There are plenty of nice trout still being caught down there, but they’re generally the minority of the catch in a day’s fishing.  Part of the fun down here is that there is something for everyone down here and for anglers of all ages.  Indicator rigs, dry/droppers, streamers, and even spotty dry fly fishing opportunity combine to make this a fun day out.  Nymphs and streamers should mirror those recommended for the Box Canyon, while dry flies will be limited to the occasional caddis or mayfly spinner, but dominated by terrestrial choices, grasshopper patterns likely ranking as first selection. 

Below Ashton Reservoir

Though there are opportunities here and there, we are leaving these sections alone for the most part.  Generally anglers in these lower reaches are finished by noon or 1 o’clock due to rising water temperatures. 

Get out there and enjoy summer while we still have it!!