Henry’s Fork, October 30th, 2021
On the lower river, Box Canyon, Cardiac Canyon holes and runs deep, and the Tubs, presenting streamer patterns is the name of the game. If you favor top water fishing, BWO life cycle patterns provide the best action.
More information from Dr, Rob Van Kirk on Henry’s Fork drainage water status follows.
Headlines:
- Precipitation yesterday was moderate and widespread again yesterday, averaging 0.4 inches across the watershed.
- Natural flow has increased by 330 cfs (17%) since Friday and is 89% of average.
- At a mean outflow of 124 cfs, Island Park Reservoir gained 781 ac-ft yesterday, 110 of which was due to direct precipitation on the reservoir surface. The reservoir is 55% full, compared with 53% full on average.
Details:
Moderate precipitation continued yesterday at all locations, averaging 0.4 inch across the watershed. Precipitation was uniformly distributed across the watershed, and even valley areas received 0.2-0.3 inch. This pushed the water-year total to date to 3.63 inches, compared with the long-term average of 2.75 inches for the whole month of October. Temperatures dropped yesterday to 2 degrees F below average, the coolest in 11 days. As a result, most of the SnoTel stations gained new snow water equivalent (SWE) yesterday. White Elephant, Black Bear, and Grand Targhee each have over 1 inch of SWE on the ground. Small chances of precipitation continue on and off over the next week, with temperatures staying near average.
Watershed-total natural flow has increased by 330 cfs (17%) since Friday, with most of that increase occurring Monday and yesterday. Although streamflow in headwater areas peaked yesterday, some of that is still making its way to the lower watershed this morning. Natural flow yesterday was 89% of average for the date, and cumulative natural flow for the water year to date has increased a percentage point to 75% of average. Diversion incidentally increased by around 30 cfs yesterday due to higher river stage and was 93% of average. Total diversion for the irrigation year to date—which ends on Sunday—is 92% of average.
At an average outflow of 124 cfs, Island Park Reservoir gained 781 ac-ft yesterday. Around 110 ac-ft of that gain was due to direct precipitation on the reservoir surface. The reservoir is 55% full, compared with 53% full on average. Over the next day or two, fill rate will gradually drop back to around 550 ac-ft/day, where it was prior to the recent precipitation event.
Rob Van Kirk, Ph.D.
Senior Scientist
P.O. Box 550
Ashton, ID 83420
208-652-3567 OFFICE
208-881-3407 CELL
208-652-3568 FAX