Immortalized in the 70s and 80s by legendary authors such as Charles Brooks and Ernest Schwiebert, the Ranch has a reputation for large, selective trout hatches and extraordinary natural surroundings. This nine-mile stretch of the Henry’s Fork is an icon in the world of American fly-fishing.

The reputation and popularity of the Ranch have led to it being the focus of more than two decades’ worth of scientific inquiry. The dozens of studies that have been completed in and around the Ranch have created a wealth of knowledge about the fishery and led to significant efforts aimed at its improvement. But, like many great trout fisheries in the western United States, the Ranch is the product of a complex set of natural and man-made influences, and the quality of angling has fluctuated widely over the years. Now, by the accounts of many anglers, the Ranch fishery has been declining for several years; that decline is measured in terms of fewer trout, less robust hatches and loss of habitat.

With this in mind, the Henry’s Fork Foundation has begun the Caldera Project, named for the 28-mile section of river from Island Park Dam to Mesa Falls that includes the Ranch. The HFF will examine and summarize the body of existing research regarding the fishery and evaluate resource management. We will also identify the unknown factors and determine how we could better manage these waters. The basic project elements for 2008 included a scientific literature review, angler surveys, fish population estimates, fish passage monitoring and print- and web-based educational outreach. In 2009, work focused on assessing the current condition of aquatic plants on the Henrys Fork and comparing it to past conditions, developing low elevation aerial photography methods of the river, operating fish traps at the Buffalo Hydroelectric Project, and assessing juvenile trout usage of small tributary streams. In 2010, an assessment of river channel and sediment conditions will be conducted on the Ranch, fish traps will continue to be operated on the Buffalo River – providing the first springtime estimate of fish return to the Henrys Fork, and restoration designs will be developed for several of the tributary spring creeks that provide critical overwintering habitat for juvenile trout.

Project partners include the Idaho Fish and Game and the Caribou-Targhee National Forest. This project has been made possible thanks to the generous support of the Ishiyama Foundation and the Marine Ventures Foundation. We also, of course, rely on our long history of cooperation with Harriman State Park.

Henry's Fork Caldera Project 2009 from Marine Ventures Foundation on Vimeo.

This study evaluates trout movement, migration and habitat use in the lower Henry’s Fork. Researchers have collected little to no scientific information about the trout populations in this part of the Henry’s Fork that has been altered by diversion dams and irrigation canals. This multi-year effort seeks to understand the factors that govern trout distribution and abundance in this section of the river.

Click here for photos, measurements, and relocations of the fish.

Click here to watch a fish surgery on YouTube!

Chester Dam was constructed in 1938 to divert water for irrigation into two canals: the Cross Cut on the eastern bank of the river and the Last Chance on the west. The facility was part of an era that resulted in seven diversion dam structures for ten canals on the lower Henry’s Fork and nine diversion dams and canals on the Fall River (not to mention the irrigation storage reservoirs at Island Park and Grassy Lake, completed just a year later in 1939). These diversions and their attendant irrigation canals created a veritable fish passage obstacle course.

In July of 2008, the Federal Energy Regulatory Commission (FERC) issued a license to hydropower developer Symbiotics of Rigby, Idaho, granting them permission to retrofit Chester Dam on the lower Henry’s Fork with a hydropower generating facility. The licensing and settlement agreement process presented an opportunity to improve fish passage at a hitherto impassable barrier to upstream fish movement, as well as improving human access to the area. Improvements include:

• Fish screens in both the Cross Cut and the Last Chance canals.
• A fish ladder to provide upstream passage to fish of all species.
• A screen on the hydropower turbine intake to prevent large fish from passing through. Fish small enough to pass through the screen and downstream through the turbines should do so with relatively low mortality.
• Permanent public river access, including improved boat launches above and below the dam and an expanded parking area. Previously, public access was not guaranteed, but entirely dependent on the Fremont-Madison Irrigation District, the Dam owners.

The Henry's Fork Foundation worked closely with Trout Unlimited and the Greater Yellowstone Coalition throughout the licensing process and these organizations are responsible for obtaining the funding for the design and construction of the fish ladder at the project. The Idaho Department of Fish and Game, US Forest Service, US Fish and Wildlife Service and Idaho Department of Parks and Recreation all weighed in to make the final license the best product it could be.

Finally, Symbiotics should be recognized for its willingness to make its project not only a viable means of generating electricity, but also an improvement for the fishery.

Long-term aquatic monitoring of the Henry’s Fork and several tributaries began in 2000. There are nine permanent monitoring sites; six are located on the main stem of Henry’s Fork from Mack’s Inn to Rexburg, and one site each is on three tributaries: Henry’s Lake Outlet, Sheridan Creek and Fall River. The Henry’s Fork Foundation has collected invertebrate density and species composition, water temperature, size and abundance of juvenile trout and species of non-game fish along transects. These data are then analyzed for seasonal, annual and spatial trends.

Click here for a pdf project summary of the Henry's Fork Long Term Monitoring: Summer 2005.

The HFF monitors upstream and downstream fish passage at the Buffalo River Hydroelectric Project. The hydroelectric project was relicensed in 2004 and several fish passage improvements were made at the facility in 2005:

• Upstream migrating fish benefit from a state-of-the-art, 270-foot-long fish ladder that was designed to allow a rainbow trout as small as four inches to pass over the twelve-foot-high dam; and
• The turbine intake was screened with a smaller openings, and the upstream face of the dam was resurfaced. These changes should prevent fish migrating downstream at the dam from being injured or killed when entering the turbines, or being trapped in holes in the dam.

These fish passage improvements were made to further connect juvenile rainbow trout from the Henrys Fork with overwintering habitat. Offspring from spawning rainbow trout in the Buffalo River and juvenile trout migrating from the Henry's Fork are able to spend their first winter upstream of the dam. After their first winter, these juvenile trout move to the Henry’s Fork where they can grow and contribute to the fishery from Box Canyon through Harriman State Park.

Fish passage monitoring includes a trap that catches fish that have migrated upstream through the ladder. Thousands of juvenile rainbow trout have moved through the fish ladder since the trap was installed in March 2006. The monitoring of fish migrating downstream past the dam began in July 2006 with the installation of a fish trap on the dam spillway. The number of rainbow trout being contributed to the Henry's Fork as a result of the fish passage improvements can now be quantified.

The HFF is working cooperatively on this project with the Caribou-Targhee National Forest, Idaho Department of Fish and Game, and Fall River Rural Electric Cooperative, owners of the hydropower project.

The distribution, abundance, and genetic status of Yellowstone cutthroat trout (YCT, Oncorhynchus clarki bouvieri) are being assessed for the Henry’s Fork, Teton, and Sinks drainages. Fisheries data from over 1,700 sampling sites within these drainages have been compiled for the years 1996 to 2009. Genetic data for YCT populations in these drainages is being used to evaluate the presence and degree of introgressive hybridization with introduced rainbow trout. YCT restoration has involved removing non-native brook trout, which compete with and replace YCT from headwater streams. YCT then are reintroduced into these streams to establish YCT only populations.

This work is being conducted by Henry’s Fork Foundation with Gregory Aquatics and in cooperation with federal and state agencies and other non-profit organizations. The project has been funded by the Jackson Hole One Fly Foundation and National Fish and Wildlife Foundation Conservation Partnership.

Historic channel straightening and overgrazing — as well as a highly altered hydrograph — have affected the Henry’s Lake outlet, resulting in the simplification of stream and riparian habitat and high erosion rates. The objective of the outlet restoration project is to restore a one-mile reach of the outlet to its historic channel on the Nature Conservancy’s Flat Ranch.

The restoration project includes three phases: 1) stream channel assessment, 2) channel restoration work and 3) post-construction monitoring.

The stream channel assessment work was completed in 2003 and 2004, working with Gregory Aquatics and River Research and Restoration, Inc. The assessment phase provided the data needed to identify and design the restoration project. The project plan was to return water to a 1-mile historic meandering section of the Outlet that had been straightened in the 1920’s. By doing so, bank erosion and channel instability would be reduced, stream habitat and riparian connection would be improved, and a half mile of stream channel would be added to the Outlet.

An excavator was used during the construction phase to remove deposited sediment from the historic channel, create pool and riffle sequences, and reestablish the stream gradient. Water was turned into the historic channel during October, 2007.

Post-construction monitoring has consisted of flow monitoring above and below the project to assess potential effects to water delivery through the project area, resurveying channel cross sections through the restored channel, and photo point documentation of the restored channel.

The Jackson Hole One Fly Foundation/National Fish and Wildlife Foundation Conservation Partnership, the Idaho Department of Environmental Quality, the Flat Rock Club, the Gibbons Foundation, and the Trout and Salmon Foundation have funded this project.