Henry's Fork Report - August 10, 2023

Henry’s Fork Streamflows

Island Park Dam:  797 cfs

Ashton Dam:  1630 cfs

St. Anthony:  1390 cfs

Fall River:  544 cfs

Last week’s wet weather and colder temperatures brought around some changes on the Henry’s Fork, some great fishing was found by those willing to adjust with the shift in conditions.  This coming week shows promise of increasingly fair weather with temps in the mid 70s in the high country and mid 80s in the lower elevations.  Flows have decreased significantly in the past days and look to be relatively stable in next week’s outlook, water temps are good throughout the system.  Water clarity decreased quite a bit out of Island Park Dam last week, but seems to be clearing just a bit in the past days.  We expect some turbidity above levels we had at the end of July, but are hoping the river will remain reasonably clear for the week to come.

Box Canyon

With flows dropping to right around 800 cfs, the Box is running at a great fishing level.  There are a few more rocks to avoid, but the features and holding water are more easily read and fished.  Turbidity in the system is at its worst coming out of Island Park Dam, but begins to even out and become more fishable after the first ¼ mile, though fishing remains decent in the upper reaches.  The trout are still hungry and fishing productive, now is a good time to experiment with a leech pattern or nymphs with hot spots and fluorescent tags.  Indicator nymphing will dominate our rigs down here for the time to come, though dry/dropper rigs can still be productive as shallow nymph rigs when fished in appropriate depths.  We are finding success with Rubberlegs stonefly nymphs, Black Bouface Leeches, and a variety of PMD nymphs (PTs, Split Backs, Rednecks 14-18).  Red and brown Zebra Midges in 14-18 are always a good bet.  Your favorite Perdigons (Olive Hot Spot, Bullet Quill, Spanish Bullet, Jake’s SH, Jig Napoleons, and even a Firestarter 14-18) will do a good job of getting you to depth and find a few hungry trout as well.  For those inclined to throw a streamer, an early or late run on a sunny day can be effective and now is a good time to add a Copper Zonker to the quiver of BFEs and Bouface Leeches.

Railroad Ranch

The Ranch has had some great fishing this past week, as well as some upsets and will vary day to day.  In the upper reaches, be on the lookout for morning and evening PMD spinner falls with rusty as well as yellow spinners in 16-18.  Afternoons can be a bit slow, but be prepared with a few honey ants in case you are lucky enough to come across some on the water, they’ve been around in small numbers but there is lots of potential for good ant fishing in the week to come.  This is also the time of year to have a few Callibaetis spinners on hand in a size 14-16.

In the lower reaches, you’ll find spinners in the mornings and evenings as well as more PMD action through the midday with some challenging trout to go along with them, these emerger-eaters can put even the most skilled anglers to the test.  You’ll want to come prepared with some of your more tricky flies for these trout:  Harrop’s Captive Dun, CDC Biot Dun, Heames’ PMD Klinkhammer, and a spattering of spinners in various profiles and shades 14-18.  Don’t forget your Honey Ants down here as well, astute Ranch anglers are usually prepared for when they’re given the gift of an ant-eating trout.  There are a few hoppers around, but not yet in any significant numbers.

Canyon Country

These flows combined with this time of year are ideal for forays into the canyons of the Henry’s Fork where anglers can find solitude, beauty, and fun fishing in a wilderness section.  Lower flows help flies penetrate holding lies that were unreachable last week.  Dry/Dropper rigs are the most common choice as deeper nymphing rigs often result in too great a loss of flies, but that indicator rig can sure be useful when pulling over to work through a likely run more thoroughly.  It’s hard to veer too far off the Rubberlegs program here for a dropper, but if that’s not happening, don’t be shy about hanging a slightly oversized and quick-sinking perdigon off of the dry fly.  Streamers are a good bet as well, we like them on a floating line and usually opt for a quick-sinking fly on a 9’ leader.  BFEs, Copper and Olive Zonkers, and even something shiny like a Kreelex or Sparkle Minnow are all good choices.

Warm River to Ashton

Lots of fun fishing to be had in this section with anglers generally running indicator nymph rigs armed with the same flies we’re using in the Box Canyon.  Always good to have a red Copper John 14 along for the ride, and now is a good time to experiment with leeches and streamers under and indicator for those wanting to target a larger trout.  Smaller flies will bring more action on smaller fish with some pleasant surprises in between.  For anglers with a stripping mentalilty, a floating line with a heavy fly or a sink tip with a less-weighted fly in the deeper runs can break up the bobber-dogging.  A hopper/dropper can bring a few fish to the surface as well while providing just enough action on the dropper to keep you in the game.

Below Ashton Reservoir

While this past week offered some spotty and interesting activity on the lower reaches, we expect this to settle back down with the sunny days in the forecast.  Water temps are relatively cool, but a hot afternoon will slow things down considerably.  Morning and evening streamer runs can provide some decent action for those inclined, while the persistent and faithful hopper-slinging angler can find a few willing participants.  A quality over quantity mindset is helpful here.