HFF's Top 10 -- 2019

At the end of each year, HFF takes a moment to reflect on all that was accomplished for the Henry’s Fork in the previous 12 months. To keep the tradition going, HFF is taking a look back at the "Top-10" programmatic accomplishments and events worth celebrating from 2019.


HFF’s Top 10 -- 2019


1.  2019 was the Henry’s Fork Foundation’s 35th Anniversary

In 1984, a small group of concerned citizens and anglers gathered together around a kitchen table in Island Park to discuss the future of the Henry’s Fork. 35 years later, 16 staff members and 18 board members strive to honor that legacy of conservation through extensive programmatic work from science and technology to river access and education.

In its first 35 years, with over 100 research, monitoring, and restoration projects under its belt, the Henry’s Fork Foundation has learned many lessons. The greatest of these lessons is the value of partnership and collaboration. The value of getting to know your neighbor and realizing there is so much more to learn, and so much more to gain, when you work together.

We all want healthy rivers and outdoor spaces for our grandchildren to enjoy. Thanks to volunteers, donors, community members, and partners, the Henry’s Fork Foundation is lucky enough to have had 35 years of learning, growing, and conserving the Henry’s Fork River and its Watershed. We look forward to 35 more.


2.  With only average water supply, precision management turned an average year into record reservoir carryover and well above average winter flow for trout

In 2019, natural flow in the Henry’s Fork watershed was 98% of average, ranking 21st out of the past 42 water years. (Read Rob’s blog for more on why natural flow is rebounding in the upper Henry’s Fork, but natural flow this year was not above average). 

Over the past few years, the Henry’s Fork Drought Management Planning Committee has set a target flow of 1,000 cfs at the St. Anthony gage to meet irrigation demand and streamflow needs in the lower watershed with a minimum amount of Island Park Reservoir draft. Statistical analysis of factors affecting draft of Island Park Reservoir show that on average, reservoir carryover increases by 4,300 ac-ft for each 100 cfs of streamflow at St. Anthony below the long-term average of 1,411 cfs. Thus, maintaining St. Anthony streamflow at 1,070 cfs in 2019 increased Island Park Reservoir carryover by an expected 14,663 ac-ft over the long-term average, all other factors being equal. This additional carryover is equivalent to a 75-cfs increase in winter outflow from Island Park Reservoir.

The reservoir ended the water year at 99,188 ac-ft (73% full), compared with the 1978-2018 average of 62,675 ac-ft 46% (full). This high carryover followed end-of-September volumes of 109,489 ac-ft in 2017 and 98,508 ac-ft in 2018. Reservoir carryover has not been this high three years in a row since 1997-1999. During those three water years, watershed-wide natural flow was 153%, 130%, and 124% of average, respectively. Watershed-wide natural flow in 2017, 2018, and 2019 was 111%, 104%, and 98% of average, respectively. These are remarkable figures showing how improved reservoir management over the past few years has increased carryover in Island Park Reservoir to the benefit of water users, water quality, and the fisheries. Fremont-Madison Irrigation District and U.S. Bureau of Reclamation deserve a lot of credit for managing the Henry’s Fork irrigation system so carefully to keep the reservoir as full as possible. 

Outflow from the reservoir during the upcoming winter is expected to exceed 500 cfs for the third consecutive year, due to high reservoir carryover and improved baseflows in the upper Henry’s Fork subwatershed.


3.  Fish populations 4th highest since record keeping began

Each year the Idaho Department of Fish and Game (IDFG) monitors trout populations in the Box Canyon section by conducting raft electrofishing surveys. These surveys provide crucial information on trout populations and size structure. This year, surveys were conducted May 13 – 15 and the estimated number of Rainbow Trout (> 6 inches) in 2019 was 4,924 per mile. Not only is this significantly higher than last year’s estimate of 2,796 trout per mile, it is also higher than the long term average of 3,034 trout per mile, and is the 4th highest since record keeping began in the 1970s.

Winter flows out of Island Park Dam are a significant factor regulating trout population in the Box Canyon, so HFF will continue to work with partners like IDFG, Fremont-Madison Irrigation District, and the Bureau of Reclamation to ensure healthy trout populations below the dam.

4.  Kokanee in the upper River

Idaho Department of Fish and Game (IDFG) fisheries staff, long time anglers, and HFF staff observed Kokanee Salmon in the upper river at significant numbers for the first time since the early 2000s. According to IDFG staff, the Kokanee count in Henry’s Lake Outlet in 2019 was the highest since 2003. IDFG will continue to monitor these populations and have additional information for those who might be interested. While many factors affect Kokanee survival, three consecutive years of high carryover in Island Park Reservoir is likely a reason for high returns of Kokanee to the upper river in 2019.

5.  HFF’s programmatic work expands to the South Fork in South Fork Initiative’s first full year

HFF’s South Fork Initiative (SFI) was launched towards the end of 2018 at requests from South Fork outfitters, anglers, and concerned citizens who hoped HFF’s model of science-based collaboration could help conserve and protect the South Fork Watershed. The Henry’s Fork and South Fork are interconnected in many ways, from water management to fishing experience. In 2019, the South Fork saw the installation of its first water quality monitoring sonde, hardware to connect that sonde to HFF’s real-time data website, its first annual macroinvertebrate sampling effort, and HFF’s SFI assisted IDFG and other partners with a restoration project on Third Creek (a tributary to Rainey Creek).

6.  Crucial Work Underway to Enhance Upper River

The Henry’s Fork near Mack’s Inn is full of cool, clear water with abundant insects, so why is that upper river fishery less productive than the Ranch, for instance? With continued development in the Mack’s Inn area and limited knowledge about the fishery there, HFF began a four-year project in 2019 assessing factors that might be limiting fishery production. Led by PhD student, Jack McLaren, the project is tackling a few key questions:

In Box Canyon, we know winter flows are the most significant factor influencing trout populations. What is the equivalent of “winter flow” for Mack’s Inn?

Existing research indicates nutrients from a wastewater treatment plant may increase aquatic plant growth, but how might plant growth affect trout populations and individual fish growth? 

Keep an eye out for future communications about this upper river project and email Jack McLaren at jack.mclaren@aggiemail.usu.edu for more information.

6. First of Its Kind Research on Lower Henry’s Fork

In 2019, Utah State University PhD student and former HFF intern, Christina Morrisett began a long-term project on the lower Henry’s Fork to assess surface water and groundwater impacts on fish and insect habitat to help inform water management for the benefit of fisheries. She wants to help managers meet irrigation needs, while also having enough water in the river for fish and aquatic species. In the first year of the project, she has learned:

Fishing below St. Anthony is great in the fall, but turns off in the summer because despite managing this section for a summer low-flow target, the target does not account for irrigation diversions downstream that take additional water from the river.

The river between St. Anthony and Parker gained water from the local aquifer in mid-July, when diversions from the river were highest and flow was lowest.

In late July, the average temperature of groundwater seeping into the lower Henry’s Fork was 58 degrees F, whereas the average temperature of the river was 65 degrees F. These groundwater seeps may provide refuge for trout from warmer water during summer months. 

To learn more about the lower river project, email christina.morrisett@aggiemail.usu.edu or follow @lowerhenrysfork on Instagram. 

(April 2019 in Box Canyon)

8.  Favorable weather – 2019 springtime temps equivalent to average temps expected in spring of 2003

Midway through the winter, the probability of a 3rd consecutive year of good snowpack looked slim. In the middle of January, accumulated precipitation and snow water equivalent (SWE) were both 78% of average. In the upper Henry’s Fork, SWE was only 63% of average, although SWE was somewhat better in the Teton subwatershed. A couple of storms late in January favored the northern part of the watershed, putting SWE in both Teton and upper Henry’s at around 85% of average at the beginning of February. Precipitation then fell on all but three days in February, moving water-year precipitation and SWE up to 120% of average. February’s precipitation heavily favored the Island Park and Ashton areas, which hadn’t seen that much snow since the late 1990s.

March was dry but cold, setting the stage for a long, slow melt of that above-average snowpack. Peak snow accumulation occurred on April 16, 8 days later than average, and equal to last year’s peak date. Peak SWE was 118% of average in both years, and this year’s snowmelt started out like last year’s—at a much higher rate than average. SWE had dropped down to average by mid-May, when an extended period of cool weather set in. Sub-freezing mornings persisted even in the valleys into the last week of June. Mean April-June temperature was 2 degrees below the 30-year average and typical of springtime temperatures last experienced in the late 1990s. As a result, snowmelt rate dropped substantially, and snow persisted into early July, about equal to average and a good three weeks later than in 2018.

In fact, 2019 springtime temperatures were equivalent to the average temperatures expected in spring of 2003. Compare that to springtime temperatures experienced in 2016, which were equivalent to the average temperatures expected in the spring of 2039.

9.  HFF partnered with the US Forest Service on a recreational use capacity study of the Big Springs Water Trail

Many anglers can attest to the beauty of the Big Springs to Mack’s Inn reach, also known as the Big Springs Water Trail, with its towering pine trees and resident moose. However, angler concerns regarding floaters in that stretch prompted a partnership between the US Forest Service and Henry’s Fork Foundation (HFF). In 2019, HFF conducted a recreational use capacity study to assess if floater use is exceeding capacity of facilities and to determine both floater and angler satisfaction with their experience. The study ran from Memorial Day to Labor Day 2019 and provided some unique insights including:

Total use estimate was 37,187 floaters.

18 percent of floaters used Mack’s Inn transportation.

90 percent of floaters ratied their experience as ‘very good’ or ‘good’.

Over half of all floating devices used were kayaks, followed by tubes (about 20 percent) and canoes (about 10 percent).

Anglers’ experience was worse than desired regarding size of fish caught, condition of fish habitat, and number of non-angling floaters on the river.


HFF has shared the full report with the Forest Service to help inform future management of floaters, but HFF is also part of a study of the factors that might be impacting size of fish and condition of habitat in that reach. Hopefully, results can help improve fishing conditions in future years. To learn more about this study and HFF’s programmatic work in the upper river, email rob@henrysfork.org.  

Photo credit: Ola Hedin

10.  HFF’s model of conservation at home and abroad  

The Henry’s Fork Foundation has long been known for using data, cutting edge technology, and the best possible science to inform collaboration and management; and recently, that modus operandi has been sought out both locally and across the globe. In the South Fork Watershed, HFF’s newest program, the South Fork Initiative, was sparked by requests from South Fork outfitters, landowners, and anglers for HFF to expand its model of conservation farther south. Farther north, HFF Executive Director, Brandon Hoffner was invited to spend two days with the Board of the Upper Missouri Watershed Alliance (UMOWA) in April to discuss nonprofit management and strategy. UMOWA is currently volunteer led, but hopes to achieve a similar framework and programmatic portfolio as HFF in the near future. Across the pond, HFF was invited to present at an angling tourism conference in Stockholm, Sweden. In April, Communications Manager, Jamie Laatsch attended the conference, discussing socio-economic research and implementation with attendees, including the King of Sweden and high ranking members of government. HFF’s Senior Scientist, Rob Van Kirk also traveled internationally this year with a team from Idaho to present on the state’s aquifer recharge efforts at a conference in Madrid, Spain.

Whether by becoming more involved in connected watersheds or by sharing our model of conservation at home and abroad, HFF will continue to strive to be an example of science-based collaboration. Expanding our scope to the South Fork has direct benefits for Henry’s Fork fisheries and telling our story in watersheds near and far will galvanize additional support for both the Henry’s Fork and fisheries conservation as a whole.