Henry’s Fork

Henry’s Fork, October 29th, 2022

Presenting streamers almost anywhere on the river will be effective. Weedier waters such as in the Harriman State Park reach (and portions of the lower river), will have interrupted presentations from time to time but resident rainbows respond to them even though it is almost traditional to present aquatic and terrestrial insect life cycle patterns. Brown trout are migrating throughout the lower river, and offering streamers during low light conditions is certainly the best way to encounter them.

Henry’s Fork, October 25th, 2022

Headlines from Dr. Rob Van Kirk’s water analysis report taken yesterday for the Henry’s Fork drainage are below

• Wet, cold weather continued yesterday, keeping monthly precipitation at 98% of average.
• Natural flow increased to 89% of average.
• At an outflow of 157 cfs, Island Park Reservoir gained 460 ac-ft yesterday and is 50% full, compared with 52% full on average.
• Water quality: Turbidity dropped at all locations yesterday; high phytoplankton growth continues in Island Park Reservoir.

Flow of only 157 cfs out of Island Park Dam makes wading in Box Canyon quite easy, and presenting streamers very effective. Rubber legs and large nymph patterns also work well. We also have great weather for BWO activity throughout the river. Bundle up and don’t put away that floating line yet!

Henry’s Fork, October 22nd, 2022

Everything we said about the South Fork applies to the lower river. For the upper river, low flow in Box Canyon makes it a good choice for wading. Streamer and nymph patterns, such as rubber legs, should work well there and in the Tubs. Don’t overlook BWOs in these locations as well as at Last Chance and in the Harriman section where wading is also easier. Weather will determine if terrestrial insect patterns will be effective. It looks like our days with 60 to 70 degree F. afternoon air temperatures are gone with snow possible.

Henry’s Fork, October 15th, 2022

It is streamer time in Box Canyon and in the Tubs. Water is low enough in the Box that walk-in-wade fishing beats fishing from a boat because of low water. Another plus is that recreational floater numbers in both places are decreasing as we cool off. Almost anywhere else on the river, terrestrial insect patterns during warm, sunny PMs are best bets to fishing success. Tiny BWOs are out during evenings at certain locations such as just above the Fun Farm Bridge.

Another strategy for this time of day on the lower river is that of using streamers to encounter migrating brown trout.

Henry’s Fork, October 11th, 2022

Sunny, comfortable days make afternoons enjoyable times to be almost anywhere on the river. BWOs, mahogany and midge activity will be somewhat muted because of bright skies, so evenings will offer best times for top water fishing.

Headlines:From Dr. Rob Van Kirk’s Henry’s Fork drainage water status report of yesterday  

• Warm, dry weather continues, with no end in sight.
• Natural flow is 74% of average, and diversion is 110% of average.
• At an average outflow of around 280 cfs, Island Park Reservoir gained 100 ac-ft yesterday and is 46% full, compared with 48% full on average.

Rob Van Kirk, Ph.D.

Senior Scientist

Henry’s Fork Foundation

P.O. Box 550

Ashton, ID 83420

208-881-3407 CELL

Henry’s Fork, October 8th, 2022

Next week during October 11th & 12th, IDF&G will be doing an electroshocking survey from Warm River to Ashton. The purpose is to study the Rocky Mountain whitefish health status and population. Until some unsettled weather moves in no change in fishing strategy should take place. Look for BWO, mahogany, and caddis activities peaking during PMs and during day time warmth hopper and ant patterns being effective. Streamers presented around first light, during evenings, and any low light conditions will be increasingly effective for migrating brown trout throughout the lower river.

Henry’s Fork, October 4th, 2022

Brown trout are migrating to spawning areas throughout the river below lower Mesa Falls. In contrast to the brown trout runs in Yellowstone park waters, the Henry’s Fork run is attended primarily by local fly fishers. Thus with fewer anglers on the river, a better chance of solitude can be realized.

In addition, the lower river still offers good terrestrial insect hatches on sunny, warm days and BWO, mahogany dun, and caddis activity. So the river offers good fishing for the top water enthusiast as well as those preferring to try wet flies to encounter the migrating brown trout.

Henry’s Fork, September 27th, 2022

Look for fishing to improve, especially because of BWO and mahogany dun activity later this week, as unsettled weather is in the forecast. Streamer fishing will be picking up almost everywhere along the river. Box Canyon, the lower river and the Tubs in particular, should be some of the best locations for trying streamers. Mid afternoons should offer the best fishing in response to terrestrial insect activity.

Headlines:  from Dr. Rob Van Kirk’s Henry’s Fork drainage water status report from yesterday follow.

• Mean temperature was above average yet again yesterday; water-year precipitation is 92% of average and may end the water year there, given a good chance of showers later this week.
• Natural flow has dropped over the past day or two, while diversion has increased a little.
• Island Park Reservoir dropped by 35 ac-ft yesterday and is 45% full, compared with 46% on average. Current outflow is around 400 cfs and should stay there for the rest of the week.
• Water quality: Turbidity at Island Park Dam has been fluctuating 1-2 turbidity units on either side of average; turbidity is at or below average at all other locations.

Rob Van Kirk, Ph.D.

Senior Scientist

Henry’s Fork Foundation

P.O. Box 550

Ashton, ID 83420

208-881-3407 CELL

208-652-3568 FAX

Henry’s Fork, September 24th, 2022

The Box Canyon remains a good choice with streamer and rubber leg patterns being effective. Submerged weeds are breaking here and on downstream through the Harrriman Park reach. On warmer days, until a killing frost arrives, hopper, patterns with and without a dropper as well as those for beetles and ants are effective anywhere on the river. The best happening on the lower river is the cooling weather. Because of it, trout are responding there to BWO and mahogany dun activity in a better measure, with streamer patterns being effective during low light conditions.

Henry’s Fork, September 20th, 2022

The Henry’s Fork features many famed locations. These tend to overshadow lesser known sections. The Tubs area is a location that takes a back seat to famed locations because its best fishing is seasonal and begins now. Most recreational boating from Big Springs to Mack’s Inn has ended, and trout migrating downstream from the Flat Ranch area reside in the deep holes here. As autumn advances these trout, as well as residents, become increasingly interested in streamer patterns. So sink-tip lines and stout leaders are in order. Very large whitefish ( stiffies) are present and are always feeding on midges. If you own a smoker and are looking to stock it, The Tubs offers stiffies ranging up to near three pounds. For sure, midge life cycle patterns will interest them.

Headlines from Dr. Rob Van Kirk’s Henry’s Fork drainage water status report compiled yesterday follow:  

• Well above average temperatures returned yesterday; mean temperature for September so far is 5 degrees above average.
• Natural flow stayed relatively constant yesterday and is 74% of average.
• Island Park Reservoir is 45% full, compared with 46% full on average. Outflow will be decreased again today to around 350-400 cfs.
• Water quality: Turbidity at Island Park Dam decreased yesterday and is back below 5 turbidity units this morning, about average for this time of year.