Henry's Fork Fishing Report - October 16, 2025

Henry’s Fork Streamflows

Island Park Dam:  90 cfs (adjusted measurement as USGS gage is reading incorrectly at 53 cfs)

Ashton Dam:  687 cfs

St. Anthony:  1040 cfs

Fall River:  529 cfs

This week’s cold and rainy weather has brought around some fishy reports from the Henry’s Fork and a welcome change from the warm and sunny conditions that have prevailed through October so far.  Cold mornings, cool days, and cloudy to partly cloudy conditions are in the forecast for the coming week, we’re hoping that keeps things moving out there!  The river is generally very low and weedy at the moment, but with good water temperatures and clarity throughout the system.  A little boost of water in the river below Fall River has come about with this rainfall, increasing some opportunity in the lowest reaches for those inclined to poke around down there.

Box Canyon

At current flows, the Box remains a bumpy ride, and boaters are likely to be walking boats more than rowing them through some sections.  Low flows are conducive to good wade fishing sessions, anglers who are willing to seek deeper holding water on foot will find decent concentrations of willing trout, and a wading staff is highly recommended.  Boaters will find the same throughout the canyon, with their time better spent where they can find deeper water.  Weeds are an issue, a frequent review of your tackle is an important part of spending the day in here!  In most cases, tungsten bead heads will provide all you need for weight, but having a few B shot around will come in handy from time to time.  Unweighted nymphs fished behind weighted ones make for a good combination at the moment.  Indicator nymph rigs are the most productive, but streamers are always a good option as well.  For flies, we like PTs, Juju Baetis, Micro Mays, Cocktail Nymphs, red, brown and black Zebra Midges #16-20, and small Rubberlegs #10-12.  For perdigons, trusties like red Jig Napoleons, Olive Hot Spots, Black Daggers, Spanish Bullets and Bullet Quills #16-20 will all do the trick as will others in similar sizes.

Railroad Ranch

This weather has been conducive to baetis hatches, and there are still some mahogany arounds, lots of rising trout out there during hatch periods, with many of them small and mid-sized.  Larger trout are around, but anglers will have to do some searching to find them.  At these flows, populations are more concentrated into areas around deeper holding water located throughout the Ranch, so be willing to take a walk if you’re seeing bugs but no rises.  This is a fun time of year in this fabled section of river with ample targets, and a great time of year for a good few hours session on the water.  It’s also a great time to introduce anglers to fishing to rising fish, as there are enough targets around for younger or less experienced anglers to find game.  Weeds are always an issue this time of year, and it’s important to develop a way to deal with them efficiently and quickly, the clock is always ticking when it comes to periods of hatch activity.

Canyon Country

At these low flows and time of year, we don’t venture into the canyons too often.  Good game can be found, but inclement weather and low flows increase exposure and make things risky.

Warm River to Ashton

Late fall is a good time to play in these waters, there is big fish opportunity for those willing to pursue it, and still decent action on small and medium-sized fish during the midday periods.  Dry fly activity can be found in slower water and near the bottom reaches of the float.  Nymphs and streamers will generally produce, but keep those dry fly rods handy in the event you come across a rising fish or two!  Fly selections should reflect those recommended for the Box Canyon, and some creative license in streamer selection is always fun when targeting brown trout!

Below Ashton Reservoir

The lower river is fishing fairly well on these cloudy days, with decent hatches of baetis and sparse mahoganies.  Dry/dropper rigs are producing as well, but activity will be generally slower during sunny periods.  Streamers are a good option at times, but be willing to adjust for the conditions you have.  For dry flies, we like to have:  Purple Hazes, Tricky Situations, CDC Thorax Mahoganies #16, Sparkle Flag Duns, Comparaduns, and Bucky’s Upright Baetis #18-20.  Nymphs are similar to those recommended for the Box Canyon, and for streamers it’s pretty hard to beat a BSA Bouface Leech #6 in white, olive or black.  Recent rains have increased flows below the confluence with the Fall River and forays into the lower reaches could be interesting endeavors this week.  Please be mindful of redds if you come across them, some brown trout will be spawning at this time, we like to leave those fish alone when we come across them, and give them the best possible chance of reproducing.

Get out there, layer up, and have fun!