Henry's Fork Report - September 21, 2023

Henry’s Fork Streamflows

Island Park Dam:  369 cfs

Ashton Dam:  1270 cfs

St. Anthony:  1130 cfs

Fall River:  490 cfs

After looming on the horizon for the past week, fall weather has finally arrived in the caldera, a string of sunny days and pleasant weather has given way to the pattern that we all hope for this time of year, stormy days and scuzzy weather.  River-wide, this pattern will encourage fall mayfly hatches and kick those fall feeding patterns into gear.  So have an extra cup of coffee in the morning, pack your puffy layers, beanie hats, rain gear and get out there to experience some of the fun fall fishing that the Henry’s Fork has to offer!

Box Canyon

Fall is a terrific season in the box canyon, low flows will concentrate fish into areas with more cover and flow, the trout are at the end of their annual growing season and at their maximum size for the year, and daily hatches of baetis will kick the trout into a feeding pattern that is more reliable than the prior weeks.  Generally, nymphs are small this time of year, choose patterns that reflect baetis and midges.  Indicator nymphing will remain the rig of choice, but any day with cloud cover is a day that can produce excellent results with a streamer.  Dry/dropper rigs are also a good choice at these flows, and now is the time to consider an October Caddis as a dry fly, with a few of these beginning to appear.  Anglers will do well to hone their hooksets with nymph rigs and proactively set the hook at the slightest indication of a hesitation of the strike indicator.  Our fly selection remains fairly similar to the past weeks:  Rubberlegs stonefly nymphs #8-12, PTs, Cocktail Nymphs and Tactical R/L PTs #16-20, Zebra Midges in red and brown #14-18, and in black #18-20, olive Hungarian Partridge Caddis Pupa #16, as well as your most confidence-inspiring perdigons (Olive Hot Spot, Bullet Quill, Spanish Bullet, Jake’s SH, red Jig Napoleon, Hollow Point) will all do well.

Railroad Ranch

These fall days on the Ranch are set into motion with the current weather situation and are characterized by daily baetis hatches with an appearance of Mahogany duns that seem to trickle on throughout the day, giving larger fish something to rise to.  This is also when we begin to see the small noses of this year’s young of the year trout as they learn to feed on small baetis, expect to see more rising fish on any given day but take the time to discern the difference between a small trout and a large one.  This difference isn’t always obvious when fall bugs are on the menu, so a sharp eye out for the subtle clues of a larger trout is important;  a slightly heavier push of water, the tip of a tail, the width of a nose, or even the sound of a sip are all telltale signs.  Expect hatches to start later on cold days and earlier when the weather is more comfortable, with prime fishing hours from 11am-4pm.  We have likely seen the end of terrestrial season, but if the sun pokes out for a few hours and things begin to heat up again, there will be moments of hoppertunity.  Our fly boxes will be prepared with baetis imitations like Quigley’s Sparkle Flag Dun, Harrop’s CDC Biot Dun, Last Chance Cripple and Paraspinner, MFC’s hi-vis parawulff, Copenhaver spinners all in #16-20.  For Mahoganies, we like Harrop’s CDC Biot Dun, Captive Dun, and Thorax #14-16, Purple Haze and Purple Craze in #14-16, and a Tricky Situation #14-16 will go a long way towards finding some successes out there. 

Canyon Country

The canyons of the Henry’s Fork hold good opportunity for those wishing to seek solitude and some fun trout fishing.  However, the cold days of fall are no time to be without plenty of cold weather gear in the canyons, be sure to bring plenty of extra layers if drifting down here.  Streamer fishing and dry/dropper fishing are the mainstays and some great trout can be found for those willing to work for them.  This is a great time of year to dig out the Purple Chubby Chernobyls and hang a stonefly underneath to look for a larger specimen, if action slows, a fast-sinking perdigon #14-16 will produce more strikes.  We favor heavy streamers on floating lines down here and usually opt for olive or black, but a copper or pearl Zonker is a good call as well. 

Warm River to Ashton

Good action on nymphs, dry/droppers and streamers can be found in this section.  Fishing is generally reliable enough to devote half of the day in the pursuit of low numbers but high quality trout, sparing the other half for some hours of nymph fishing for more action on smaller trout.  Fly selection is similar to the Box Canyon, but add in some leech patterns to hang under an indicator.  Brown trout are shifting their positions and their attitudes changing, creating some opportunity for the streamer anglers out there.

Below Ashton Reservoir

Cloudy days bring out the best in the fishing down here and we hope to see baetis hatches get into an established pattern this week.  Mahogany duns will be sparse but present as well.  Generally, mornings will be spent fishing sub-surface with nymphs or streamers and afternoons will present some dry fly opportunity.  Be sure to bring along some small baetis nymphs and perdigons as well as Rubberlegs for nymphing, and a dry fly selection that mirrors our Railroad Ranch recommendations, maybe throwing in a few more hi-viz patterns with either colored posts or black wings for better visibility in flat light scenarios.  For streamers, it’s hard to beat a BSA Bouface in olive or black, and a Sculpin Snack or Sparkle Minnow for days when the sun pokes out from the clouds.

Have fun out there and stay warm!