Henry’s Fork

Henry’s Fork, October 14th, 2023

A day, like today, with overcast skies and minimal wind is ideal this time of year for good fishing. Decreasing water temps, good overhead cover, and excellent dissolved oxygen make for active salmonids. Terrestrial insects may be inactive, but midges, all day, and PM BWOs mean active fish throughout the river. Brown trout are migrating to spawning areas and streamer patterns will be the best way to encounter them. Rainbow trout will follow to pick off drifting eggs which means easy protein.

Henry’s Fork, October 10th, 2023

Headlines from Dr. Rob Van Kirk’s Henry’s Fork Drainage Water Status Report Filed Yesterday, October 9th

• The new water year started out near average in temperature and wet, continuing the pattern that started in early August.
• More precipitation is expected tomorrow through Thursday.
• At an average outflow of 341 cfs, Island Park Reservoir has gained 284 ac-ft/day over the past six days and is 67% full, compared with 48% on average.
• The upper Snake River reservoir system is filling slowly and is 43% full, compared with 39% 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

208-652-3568 FAX

[email protected]

With unsettled weather the next few days, look for good fishing results throughout the day whether your choice may be top water and near such because of fish responding to midge, BWO or mahogany dun activity or through presenting streamer patterns to browns migrating in the river below Surprise Falls ( that six foot dip in the river below Lower Mesa Falls ).

Henry’s Fork, October 7th, 2023

Well-fed rainbow from the Tubs area

With less daylight and cooler air temperatures, aquatic vegetation is breaking up along the entire river. It can be a nuisance when drifting veggies impact the course of your drifting fly pattern, but it makes for less places for fish diving into weed beds on trying to escape from that fly they have taken. BWO, and mahogany dun life cycle, honey ant, and smaller hopper patterns make up the best top water patterns anywhere on the river. Try double nymph nymph rigs, fly rod jigs and streamer patterns in deeper water such as in Box Canyon, the Tubs and just below Coffee Pot rapids. Unsettled weather is coming up around mid week, so all these technique suggestions should be appropriate.

Henry’s Fork, September 30th, 2023

Popular Lower River Boat Launch Facility

There have been no deep killing frosts yet with low early morning temperatures typically hovering in the low to high twenties in degrees F. until mid day warming happens Fewer daylight hours and cool nighttime air temps help break up aquatic weeds throughout the river this time of the season. Drifting mats can interfere with both wet and dry fly fishing, so stay alert for these coming through the water you are fishing. Unsettled weather the next few days will enhance BWO and mahogany dun activity, so keep their life cycle patterns in that fly box. The same weather will enhance pitching streamer patterns into good holding water, especially with the slightly lower than normal flows in the entire river. Remember that proper placement of these overrides pattern choice. An alternative to these, are trying double nymph rigs in such locations as Box Canyon and throughout the lower river.

Henry’s Fork, September 26th, 2023

It has not been cold enough to kill all the hoppers, honey ants and beetles. They are active along the entire river from St. Anthony upstream to the Flat Ranch. Wait until the mid-day sun warms things enough for them to become active. This activity could diminish this weekend as unsettled weather is expected. However such weather could enhance mahogany dun and BWO activity and make pitching streamers more effective . A few trico spinners are around in mornings.

Here are headlines from Dr. Rob Van Kirk’s Henry’s Fork Drainage water status report filed yesterday, September 25th.

• Last week was cool and very wet, boosting water-year precipitation to 111% of average with just 6 days left in the water year.
• Cool, wet weather is expected to kick off the new water.
• Diversion and natural flow both dropped over the weekend after heavy precipitation on Thursday and Friday.
• At an average outflow of 466 cfs, Island Park Reservoir gained 151 ac-ft/day over the past three days and is 64.9% full, compared with 45.9% on average.
• Water-quality data indicate decreased aquatic productivity watershed-wide as the growing season wanes.

Chester Dam

Henry’s Fork, September 23rd, 2023

A Killing frost is likely on the upper river. Being the first of the season, terrestrial insects in sheltered places are not totally impacted yet and fish will be looking for them. Afternoons will feature BWO and midge hatches, and such as Box Canyon and the Tubs will be great places to try streamers as well as some trying top water fishing because remaining insects. More numerous and severe killing frosts are lined up for the coming days for sure, and as on the South Fork the opposite ends of the effective fly activity spectrum ( BWOs and midges over to streamers and woolly bugger variations.will be increasingly effective for successful fishing.

Henry’s Fork, September 19th, 2023

Henry’s Fork Drainage Water Status Report Filed Yesterday by Dr. Rob Van Kirk

Headlines

• Last week was on the warm and dry side, dropping water-year total precipitation to 110% of average.
• Diversion and natural streamflow each decreased a little over the weekend, keeping lower-watershed conditions stable.
• At an average outflow of 469, Island Park Reservoir gained 67 ac-ft/day over the weekend and is 64.1% full, compared with 45.5% on average.
• Water quality continues to be good to excellent throughout the watershed.

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

The Tubs: A Great Place for Streamer Fishing on the Henry’s Fork

No killing frosts to date anywhere along the river. That means terrestrial insects, Early AM spinner falls, BWOs (activity peaking during PMs), mahogany duns (activity peaking during mid-day) and caddis (activity peaking during PMs) remain in place making top water fishing attractive. Unsettled weather is coming in a day or so and will remain for the rest of the week. Let’s see what impact it has on top water fishing and dry dropper rigs which have been so effective up and down the river. Such weather is sure to be good for pitching streamers and for BWO activity.

Henry’s Fork, September 12th, 2023

No killing frosts on the upper river to date. That means terrestrial insects remain numerous but spinner falls are diminishing. For the river below, same situation (excepting for BWOs), but brown trout are beginning to move, so streamers are in order during low light conditions. Some other good news is that recreational boating on the river is fading away on the river.

Headlines from Dr. Rob Van Kirks Henry’s Fork Drainage Water Status Report Filed September 11th.

• Last week was average in temperature and wetter than average; water-year total precipitation is 111% of average with only 20 days remaining in the water year.
• Diversion and lower-watershed stream flow targets continue to be met with no reservoir draft.
• At an average outflow of 468 cfs, Island Park Reservoir has gained 159 ac-ft/day over the past five days and is 63.5% full, compared with 46.1% on average.
• Water quality is excellent throughout the watershed in all measures.

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

[email protected]

Henry’s Fork, September 9th, 2023

Dogs can be great companions during fishing outings

There are a few early in the day spinner falls left from Last Chance downstream through the Harriman State Park reach, but by late morning, it remains best to switch to terrestrial insect patterns especially hoppers and ants (with and without droppers). These should be presented close to banks through long, drag-free drifts. Doing such applies to anywhere on the river. Try presenting streamer patterns up tight to well vegetated banks any where along thee river especially during low light conditions. There have been no killing frosts of any consequence on the upper river to date.