Henry’s Fork, December 16th, 2023
Access remain good from Ashton Dam on downstream. Streamer and woolly bugger types are good bets for action with the middle of blue bird days being the only time for comfortable fishing. Make sure there are no holes in those waders!
Headlines from Dr. Rob Van Kirk’s Henry’s Fork Drainage Water Status Report Filed Yesterday
- Another dry day dropped water-year total precipitation to 102% of average and SWE to 76% of average, with no appreciable precipitation on the horizon.
- For the first two weeks of December, natural flow was 90% of average at Island Park and 89% of average at Ashton. Most other stream gages are affected by ice.
- At an average outflow of 400 cfs yesterday, Island Park Reservoir gained 56 ac-ft and is 88% full, compared with 67% full on average.
Details worth noting for the drainage
Unfortunately, no appreciable precipitation is indicated for at least the next week. Some very light precipitation is possible late next week, with high uncertainty in forecasts and outlooks beyond that. The general trend is still toward moderate to heavy precipitation to our south and dry conditions from here northward. Temperatures are expected to be above average, although inversions are keeping temperatures in the valleys a little lower than had been anticipated a few days ago.
With most stream gages affected by ice, accurate estimates of natural stream flow are not possible on Fall River and Teton River. In the upper Henry’s Fork, natural flow over the first two weeks of December was 90% of average at Island Park and 89% of average for the whole subwatershed, measured at Ashton. Streamflow in the Buffalo River was 98% of average, although the gage record there is not as consistent as it as at other locations. In any case, natural flow—while much better than it was last year at this time—is still below average in the upper Henry’s Fork.
Together, the three reservoirs in the Henry’s Fork watershed are 88% full, compared with 75% full on average. The upper Snake River reservoir system is filling faster than average and is 61% full, compared with an average of 52% full for the day.
Dr. Rob Van Kirk
Senior Scientist
P.O. Box 550
Ashton, ID 83420
208-881-3407 CELL