Henry's Fork Report - September 7, 2023

Henrys Fork Streamflows

Island Park Dam:  440 cfs

Ashton Dam:  1340 cfs

St. Anthony:  1270 cfs

Fall River:  522 cfs

The variable weather of last week created some great opportunity on the Henry’s Fork, the coming week promises more stable weather and temperatures.  Some of the most beautiful days of the year are ahead of us with good angling opportunity for those who know what they’re after and where to look for it.  Water clarity is very good throughout the system, with the exception of right below Island Park Dam.  Water temps are in good shape throughout as well.

Box Canyon

The Box is a great place to be this time of year and anglers are finding some terrific fishing with rigs of their choice.  Though indicator nymphing remains the primary choice for most anglers, dry/droppers and streamer rigs are definitely worth trying.  Lower flows mean it’ll take a bit longer to get through the canyon and the ride much more bumpy than a few weeks ago.  However, low flows make for easier reading of water and the ability to fish nymph rigs with less external weight, allowing for better detection of subsurface takes.  I know we say it all year, but it's especially true at this time of year that anglers must be proactive about setting the hook, seeking the slightest of indications on the strike indicator as a cue to set.  Good streamer opportunity where the water is white and roiling, but sunny days will put a slow to this after the first mile.  Our top choices for flies at this time are:  Rubberlegs stonefly nymphs 8-12, PTs and Tactical R/L PTs 16-18, Olive Hungarian Partridge Caddis 14-16, Zebra Midges red and brown 14-18, Rednecks 16-18 as well as your trusty perdigons (Olive Hot Spot, Frenchies, Spanish Bullet, Bullet Quill, Jig Napoleon 14-18, and Jake’s SH Perdigon 16-18) doing what they do best, sinking quickly in moderate currents without requiring additional weight to get to where the fish are holding.  For streamers, consider throwing a Copper Zonker, olive or black BFE and Bouface Leech, or a Sculpin Snack if things are sunny and you stubbornly want to strip a streamer anyway.

Railroad Ranch

These are the days that bring Mahogany duns out to play, they are now present throughout the Ranch, but will higher in number when we have overcast conditions.  Mahoganies can be sparse but they are an important food source at this time of year and even when there’s not many they can clue you in to the location of a trout that is looking up.  An ant, beetle, or hopper pattern just might be what that fish will eat but the mahogany dun is a great trout location device.  If locked into mahoganies, be prepared with some emerger patterns.  Be ready for sparsely rising trout and be willing use your imagination to put the pieces of the puzzle together when trying to formulate an image of how a target is moving out there.  A good and confident 40-50’ cast is a strong asset at this time of year.  I like a faster action 5 weight for fishing down there at the moment, something that can put out a long and semi-precise shot quickly and efficiently.  One cast per rise is a good cadence to consider out there at the moment, and a healthy dose of patience between rise forms is a must.  Don’t be shy about showing a target a terrestrial, there are hoppers, flying ants, and some beetles around, these trout are pursuing multiple sources of food at this time of year.  12’ leaders and plenty of 5X are a good add to the kit.  6X might just find its way to the end of your line on a difficult target.  Flies we are carrying in our Ranch box right now are:  Copenhaver spinners and Harrop’s Paraspinners in rusty and cream in 16-20, Challenged PMD 16-18, Heames PMD Klinkhammer PMD 16-18, CDC Biot Duns, Thorax Duns in both Mahogany and PMD 14-18, Harrop’s and Heames’ Honey Ant  and the Shimazaki Ant 14-18, a handful of your favorite hoppers like the Moorish and a Mimic in 6-10, and a few Mahogany CDC Captive Duns 16. 

Canyon Country

These early days of September when the weather is fair are terrific days to venture to the canyons in search of solitude and some quality trout fishing.  Dry/dropper rigs are the norm with hoppers or Chubby Chernobyls up top and stoneflies or fast-sinking beadheads below being the most reliable combinations.  Streamer fishing is always fair game in the whitewater and can be used under an indicator if you have some flies you don’t mind losing on lava rocks.  At these flows, there are lots of exposed rocks and some oarsmanship is required, a raft as a vessel is a must for all but the most experienced oarsmen.

Warm River to Ashton

Some great days have been had this last week and some great ones to come for anglers looking for good action and a shot at a few quality trout.  Fishing should be good with sunny weather or overcast down here with indicator nymphing rigs, dry/dropper rigs and streamer rigs all playing at the moment.  For streamer fishing, consider playing around with floating lines as well as a sink tip to ply the variety of waters in this section in different ways.  Nymph selection should mirror that of the Box Canyon, but be sure to have some brown Zebra midges and add a few leeches to try under an indicator.  Dry flies should represent terrestrials, hoppers being the primary one. 

Below Ashton Reservoir

Fishing on the lower river will be weather dependent and more dependable in another week or two.  Water temps are in good shape down there but an overcast day will be better than a bright and sunny one.  Streamer fishing is good when there are clouds and in the morning hours, hoppers can bring a few to the surface on a sunny day, and nymph rigs will produce in the right runs and slots when needed.  Fly selection should reflect baetis and mahoganies in 14-18, for streamers we love the olive BSA Bouface Leech in a 6, but Sculpin Snacks and MFC’s Sparkle Minnow in sculpin color are a good choice as well.  Streamer enthusiasts might consider using an intermediate line in place of a floating line for better hookup ratios in shallow water.

Good luck and most importantly, have fun out there!