Henry's Fork Fishing Report - September 3, 2026

Henry’s Fork Streamflows

Island Park Dam:  884 cfs

Ashton Dam:  1440 cfs

St. Anthony:  1290 cfs

Fall River:  393 cfs

The Henry’s Fork has experienced a “better than expected” water quality year to date and conditions remain fair out there throughout the system.  However, they are likely to deteriorate in the upper river as turbidity is expected to get much worse in the coming week, likely lasting for at least most of September.  On a lighter note, conditions should remain fishable and improve in the lower river reaches, especially below Mesa Falls.  Anglers should keep an eye on the Henry’s Fork Foundation’s Water Quality site to watch turbidity spikes throughout the river.  Anything around 5 NTUs is pretty normal and anything over 10 NTUs is getting pretty darn dirty.  So get out there while fishing is still decent in the upper river and stay tuned!

Box Canyon

A recent uptick in flows has things moving along a bit quicker in the Box Canyon, and a bit more turbid as well.  A close eye on the turbidity data is an important element to each outing from here on out.  Conditions are good at the moment, but likely to get worse quickly as the reservoir draws down too low for the hydro intake and all water will have to come out of the tube on the west side of the dam.  As water gets more turbid, consider using flies with fluorescent hot spots or thread wraps.  Water temperatures will be fine from here on out, but keeping flies visible to trout is important.  Not much has changed in the flies department, we’re still liking the following:  PTs, red and brown Zebra Midges, Split Case PMDs, Rednecks #14-18 and Rubberlegs stonefly nymphs and SJWs #10-12.  Many perdigons will work but we especially like Olive Hot Spots, Spanish Bullets, Jakes’ SH, Black Daggers and red Jig Napoleons #16-18 this time of year.  For streamers, we generally like black and olive or a combination of the two, but a copper Zonker is an old time favorite as well. 

Railroad Ranch

Lots of small spinners around, along with sparse callibaetis, early onset mahogany duns, PMDs, baetis and the occasional flying ant fall have things falling into a rhythm of “You Can’t Always Get What You Want” sort of mood, so be prepared for a number of different scenarios.  Generally, targets have been sparse and minimal, but present for those who value the hunt and spend time looking for them.  Though water clarity conditions are expected to deteriorate, flows are low enough to keep it interesting if the right bugs are present.  Time will tell, and September is typically a month that warrants a few days walking the Ranch.  Seeking spring water inputs which stabilize otherwise unfavorable conditions can be a good approach at this time of year.

Canyon Country

We expect canyon country to keep on fishing well as it has in the past, providing anglers with fun days of dry/dropper fishing in a wilderness setting.  Some of the most beautiful days of the year are before us and these canyons can be spectacular.  As the river above can struggle with weeds and clarity issues, the canyons seem to hold up and provide anglers with fun days regardless.  A Chubby Chernobyl and a range of droppers are usually all you need down here, we like stoneflies first, second, and third, followed by large mayfly and caddisfly nymphs.  Streamers can be fun as well.  Remember that inflatable rafts and solid oarsmanship are a must in these sections.

Warm River to Ashton

This section has fished well all summer and shows plenty of promise that it’ll hold on through the end of the season.  Anglers down here should come prepared to fish indicator nymph rigs, but be willing and open to streamer fishing and dry/dropper rigs.  This is a good time of year to start playing around with different streamer tips, fly sizes, and retrieves, there are some large brown trout to be found here and there.  The average catch down here are small to medium sized trout but each day has a few big surprises.  Flies should be reflective of those recommended for the Box Canyon.

Below Ashton Reservoir

The lower river had a recent uptick in activity with some of the cooler weather and rain that we experienced last weekend, every little bit helps.  As water temperatures continue to drop into the first wek of September, it is typical that things will begin to move along here during cooler periods.  Anglers should still expect fishing to favor clouds and cooler weather, and sunny days to be more difficult.  Indicator nymphing rigs, dry/droppers, and small streamers can all play down here at times.  We’ll look for this to continue improving as the month progresses.

Get out there and have fun!!