Henry's Fork
Through applying a scientific approach Dr. Rob Van Kirk, Science and Technology Director for the Henry’s Fork Foundation, is the best predictor of Henry’s Fork fishing projections for the upcoming season. These follow.
If you recreate on Island Park Reservoir or fish the Henry’s Fork upstream, the news is good. The reservoir will drop rapidly in July but will likely end the summer with volume about where it has the past few years. That’s enough for reasonable survival of kokanee and trout that migrate into the upper Henry’s Fork. Thanks to collaborative precision water management and modern irrigation infrastructure, end-of-season reservoir contents will likely be around 20,000 ac-ft more than we would have seen under pre-2018 management, providing benefits to water quality, fisheries, flat-water recreation, and irrigation supply.
If you primarily fish between Island Park Dam and Pinehaven, the news is not so good. Although anglers will no doubt find some good fishing in some locations at certain times of year and times of day, generally you can expect a few weeks of high outflow from the dam in July, periods of high turbidity during mid- to late-summer, high water temperatures in July and August, below-average trout numbers (except a strong cohort of 2-year old fish coming from good winter flows in 2023/2024), and inconsistent hatches. Flow during late September and October will again be very low to store as much water in the reservoir as early as possible to maximize winter outflow for juvenile trout survival. All of these less-than-desirable outcomes are a function of warmer spring and summer temperatures and much lower water supply than we experienced in the 1970s–-1990s. Please read the technical report to learn more, including how HFF’s DIRTT plan can improve water quality and hatches.
If you fish between Mesa Falls and St. Anthony, conditions will be good and very similar to those over the past few years, subject to weather conditions. Fish populations and hatches are stable and relatively independent of water supply in these river reaches, and I don’t anticipate any changes this summer. The only negative aspect may be low flows again in the fall as managers try to store as much water as possible in Island Park Reservoir to maximize winter outflow for juvenile trout survival on the Caldera.
If you fish between St. Anthony and Parker, that reach will look very much like it has for the past five years. Flow at Parker will be held at the 350 cfs target for all of July and August and probably some of June and September too, depending on weather. That target was set primarily to keep as much water in Island Park Reservoir as possible. Mid-summer fishing will generally be slow, but anglers in the know will catch some large brown trout in the fall after flows come up and water temperatures cool.
The Henry’s Fork Foundation’s recently released the 2024 technical report to their web site. It contains all of the science behind these predictions.
Fly Patterns to Use:
