In this blogpost, learn about what we know, what we don’t know, and how you can help by reporting the hatches you see (or don’t see) every time you visit the river. Check out the Henry’s Fork Hatch Survey today at tinyurl.com/hfhatchreport.
The Henry’s Fork Foundation has been monitoring aquatic macroinvertebrates (insects) at multiple locations since 2015. Each March (normally on St. Patrick’s Day), HFF and a team of entomologists from River Continuum Concepts head out to the Henry’s Fork to scrub rocks and collect bugs from the river-bottom for expert identification and robust analysis to answer questions like:
As scientific river detectives, we pair aquatic insect numbers with water quality and streamflow data and run it through rigorous statistical analysis to better understand changes to the macroinvertebrate community. What have we learned so far? A decade of data show that aquatic invertebrates on the Henry’s Fork are largely happy and healthy. When it comes to Pale Morning Duns, we are seeing declines in abundance at Flat Rock and St. Anthony, but no trends one way or the other at Last Chance, Osborne, or Marysville. Overall, our bug metrics are as good as or better than any other popular western trout stream.
But anglers are reporting wonky, pleasantly unexpected, or downright disappointing hatches—in stark comparison to the consistent hatches Henry’s Fork anglers have longtime counted on in planning their fishing day or fishing vacation. What’s up with that? How can we have strong, stable insect populations and unreliable, inconsistent hatches?
There are so many possibilities. These river bottom-living bugs may be hatching at different times of day or maybe even multiple times per year. Maybe it’s about weather or water temperatures or streamflow. We don’t know. And we need your help.
At HFF, we can’t be everywhere on the river all the time. But we can just about get there by relying on all of you, the Henry’s Fork community, to be our eyes with every trip to the river—whether there’s a rod in your hand or not.
After every river visit, please fill out our survey. Tell us when you visited the river, where you visited the river, and what you saw (even if you saw nothing at all).
This is a numbers game. With enough observations, you can help us build a more complete picture of the river and contribute to innovative, science-based river conservation. Add the Henry’s Fork Hatch Survey to your river routine and invite your fishing buddies to do the same. It takes less than 2 minutes.
Extra Info:
Your input is valuable. Thank you for your contributions so far and let’s keep it going!
As it is the afternoon of December 31, I am closing the year with my annual fish-of-the-month blog, this one at the end of my 11th year of catching a fish in my home waters in each month of the year. To spare you the math, that’s 132 consecutive months of catching a wild trout or whitefish (and in some years I’ve fair-caught suckers and shiners, too) within a three-hour drive of my home in
In this blog post, we 1) present our turbidity and suspended sediment data, 2) explain our suspended load calculations, and 3) provide some additional information justifying why we think that a substantial amount of bed load was transported into the Henry’s Fork in addition to the suspended load. Since first observing high turbidity in Thurmon Creek and the Henry’s Fork downstream associated with the Silver Lake drawdown in November 2025, HFF’s Science and Technology team
Written by Doris Squeri Tom and I met on our first day of grad school back in 1982. We were both broke and stressed, and we both loved the outdoors, so I decided that an affordable way to relieve some of that stress might be to learn how to fly-fish. We had learned to fish with our dads when we were very small, but it was bait fishing, and we wanted to try something new.
The Henry’s Fork Drought Management Planning Committee (DMPC) met on Monday, November 24 to set this winter’s outflow and reservoir-fill strategy for Island Park Reservoir—an annual decision with implications for winter trout habitat in Box Canyon and the Ranch. Winter Outflow: What’s Coming on December 1 Beginning December 1, outflow from Island Park Dam will increase, bringing winter streamflow through Box Canyon to ~380 cfs from December through February*. That equates to 76% of Box
