Fishing Reports

Henry’s Fork, July 12th, 2022

Headlines from Dr. Rob Van Kirk’s latest water report for the Henry’s Fork follows.

Headlines:  

• Mean temperature yesterday was 2 degrees F above average; water-year precipitation stands at 90% of average.
• Natural flow dropped another 3% yesterday, while diversion increased to 99% of average. Water rights priorities are near the median for the date.
• Outflow from Island Park Reservoir was increased to 1460 cfs yesterday to accommodate increased diversion into the Crosscut Canal.
• Diversion and reservoir outflow will remain high for the next 2-3 weeks, as hot, dry weather continues.

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

Evenings ( try caddis and PMD and gray drake spinner patterns) and early AMs ( spinner patterns again) are the best times to fish the lower river where terrestrial insects are beginning to appear in good numbers. A bit early for these along the upper river except ant and beetle patterns should always be in that fly box Variable flow out of Island Park Reservoir impacts fishing from Box Canyon to Riverside. PMDs, Flavs and green drakes are diminishing a bit (AM and PM spinner falls bring action) except for PM brown drakes in lower Harriman offering best activity. PM caddis activity is reliable everywhere.

Henry’s Fork, July 9th, 2022

The river from Ashton Dam downstream is beginning to warm as our “dog days” are here. This means best fishing will be early AMs and evenings, Major aquatic insects are diminishing, but terrestrial insects will soon be plentiful. Wading and boat traffic on the Last Chance-Harriman section is high, but fishing is good as the usual aquatic insect hatches continue at good levels.

Plenty of water ( currently about 170 cfs) is flowing through the river at the Flat Ranch Preserve. This flow started late because of water managing efforts in this drought year. That means fewer fish were swept downstream out of Henry’s Lake than usual. Nevertheless, the river here is worth a try.

Henry’s Fork, July 5th, 2022

We have reports of recreational floating traffic on the river; Box Canyon and the entire lower river between above Chester seem to be favored locations. Consider that these folks do not understand angling etiquette. So be patient. They have just as much right to enjoy the river as do anglers. Best time to fish around them is early and late in the day.

All traditional hatches are in full swing along the river: Green drakes, flavs, PMDs, PM caddis abound with a few golden stones. Brown drakes are appearing in evenings on lower the river at Harriman East making Wood Road 16 an up and coming favored location. AM and PM spinner falls are good times to be on the river whether it be Last Chance-Harriman State Park waters or the lower river. These times of day minimize recreational traffic. Also dry-dropper combos seem to work everywhere. Try a dry blond humpy over a bead head nymph of your choice

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

Headlines:  

• The first 4 days of July were slightly on the warm side of average, and a few thundershowers kept water-year precipitation at 91% of average.
• Natural flow has dropped by 1-2% per day over the past four days, while diversion has stayed relatively constant.
• Since an outflow increase on Saturday, Island Park Reservoir outflow has averaged 991 cfs, and the reservoir has drafted at 930 ac-ft/day. Additional incremental increases in outflow are expected.
• Water quality: Water temperatures have been optimal except at St. Anthony, while turbidity is still above average at all locations upstream of Ashton Reservoir. 

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