Henry’s Fork, January 11th, 2022
Excerpts From Dr. Rob Van Kirk’s Henry’s Fork drainage water report for today are below.
Headlines:
- Dry conditions have set in for around 10 days, during which water-year precipitation and SWE will fall with respect to average and reservoir fill rates will drop.
- Water-year precipitation is 116% of average, and SWE is 104% of average this morning.
- At a mean outflow of 218 cfs, Island Park Reservoir gained 227 ac-ft yesterday, compared with 265 ac-ft/day needed over the remainder of the winter to reach the April-1 target.
Details:
Mean temperature yesterday was 5 degrees F below average. Water-year precipitation dropped to 116% of average and SWE to 104% of average. Dry conditions are expected to last into the beginning of next week, by which time SWE will be 5-7% below average again.
At a mean outflow of 218 cfs, Island Park Reservoir gained 227 ac-ft yesterday and is 77% full, compared with 72% full on average. Since December 1, the reservoir has filled at 295 ac-ft/day, ahead of the 265 ac-ft/day needed over the remainder of the winter to reach the April-1 target 126,000 ac-ft (93% full). If precipitation in Island Park stays above-average for the rest of the winter, as is expected, the reservoir will reach the April-1 target at an average outflow of 216 cfs, within measurement error of current outflow. If reservoir fill rates deviate too much one way or the other from forecasts, outflow adjustments will need to be made later in the winter to keep the reservoir on track to meet the target.
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