Author: Bruce_Staples

Henry’s Fork, December 13th, 2022

Here is some great news from Rob Van Kirk’s Monday, December, 12th Henry’s Fork drainage SWE (snow-water equivalent) report.

Headlines:

• Precipitation over the past three days increased the water-year total to 124% of average and SWE to 145% of average.
• Since outflow from Island Park Reservoir was increased last Thursday, the reservoir has gained 344 ac-ft/day and is 64% full, compared with 65% full on average.

Details:

Precipitation over the past three days ranged from 0.04 inch at Alta to 1.3 inches at Grassy Lake and averaged 0.62 inch for the watershed. That increased water-year precipitation to date to 124% of average and snow water equivalent (SWE) to 145% of average for the date. SWE at all SnoTel stations is in the top one-third of water years since 1989. Generally wet, cold weather is forecast for the foreseeable future.

Since outflow from Island Park Dam was increased to around 195 cfs last Thursday, the reservoir has gained an average of 344 ac-ft/day. Around 75 ac-ft of that has been due to direct precipitation on the reservoir surface. The reservoir is 64% full and within 900 ac-ft of average for the date.

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, November 8th, 2022

Looks like skis or snowshoes are now standard equipment for fishing much of the Henry’s Fork

Headlines:  from Dr. Rob Van Kirk’s Henry’s Fork drainage snow-water analysis report of today.

• Precipitation averaged 0.77 inch across the watershed yesterday, favoring the Ashton/Fall River area.
• New SWE ranged from 0.5 inch to 1.5 inches; the watershed total is over two times average for the date.
•  At an outflow of 128 cfs, Island Park Reservoir gained 717 ac-ft yesterday and is 55% full, compared with 57% full on average.

Details:

Precipitation yesterday materialized as forecast. Station totals ranged from 0.33 inch at Rexburg to 1.4 inches at Black Bear SnoTel. The heaviest amounts fell in the Ashton/Fall River area. The watershed average was 0.77 inch, increasing the water-year total to 137% of average. All SnoTel stations received new snow water equivalent. Current SWE is the highest for the date in the 1989-2022 record at Lewis Lake Divide, Pine Creek Pass, and Island Park. Watershed total SWE is over two times the average for the date. An additional 0.25-1 inch of water equivalent is expected over the next two days, before cold, dry weather settles in later in the week.

Natural flow increased yesterday in response to a rain/snow mix early in the day and was 81% of average yesterday.

At an average outflow of 128 cfs, Island Park Reservoir gained 717 ac-ft yesterday, 200 of which was from direct precipitation on the reservoir surface. The reservoir is 55% full, compared with 57% 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, November 1st, 2022

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

• With the first month under our belt, water year 2023 started right where 2022 left off: slightly warmer than average, precipitation at 91% of average, and natural stream flow among the lowest on record.
• The first very cold weather of the fall arrives tomorrow, and heavy precipitation is expected to begin Saturday and last well into next week.
• At an outflow of around 130 cfs, Island Park Reservoir gained 493 ac-ft yesterday and is 52% full, compared with 55% full on average.

Upcoming weather may make fishing the upper river a challenge. Fishing on the lower river should not be as challenging with respect to air temperatures but stronger winds will make dry fly fishing tougher and diminish hatches.