Fremont County operates a wastewater treatment facility (WWTP) on Forest Service ground in Last Chance. With the continued growth of Island Park, the WWTP already operating in excess of wintertime limits, and the Henry’s Fork seeing increased concentrations of phosphorus and nitrogen, it’s time to start making moves on an upgrade. That’s why, at a recent Henry’s Fork Watershed Council tour, Fremont County, the City of Island Park, and Forsgren Associates shared plans for an upgrade with tour participants.
The WWTP is a land-application facility wherein treated effluent is applied to land owned by the USFS as irrigation water. Effluent application rates are at or below the absorption capacity of brome grass and local soils, preventing the conveyance of nutrients and other pollutants to surface water or groundwater. Permits for WWTPs need to be renewed every 5 years and the Forest Service is no longer accepting new permits for treatment here, which prevents any expansion. Redesigning the Last Chance WWTP is necessary because the terms of the operating permit reduce the amount of allowable effluent application, particularly in winter when evapotranspiration is virtually zero. The Last Chance facility completed a facility planning study in 2020 to begin looking at upgrades.
The Last Chance WWTP is operating in excess of allowable wintertime land application and anticipates exceeding summertime limits in the next decade.
The Henrys Fork downstream of Island Park Reservoir is enriched in phosphorus and nitrogen, increasing concentration and load. Productivity increases can result in greater algal and submerged vegetation growth. Changes in plant growth have been demonstrated to affect fish habitat, the aquatic macroinvertebrate community, dissolved oxygen depletion, and the fishing experience in the Henrys Fork.
Enhanced productivity increases the chance of harmful algal blooms, oxygen deprivation, and irreversible changes to fish habitat and the aquatic insect (macroinvertebrate) community.
These changes pose serious threats to the vital recreational resources that support a $30 million economy and the very development that requires a new WWTP. Any surface discharge would contribute new phosphorus and nitrogen to the Henrys Fork.
The existing system involves aeration, clarification, and disinfection. In collaboration with the County, HFF ensured that the final design proposal incorporates advanced nutrient removal technologies (i.e., screening, grit removal, filtration, etc.) and a clear regulatory point of compliance for treated effluent discharge to address these ecological concerns. This improvement will help mitigate the risk of further nutrient enrichment in the river and protect the aquatic ecosystems.
The total cost of the upgrades is now estimated at $14 million. The project is on an ambitious timeline, with plans to secure IDEQ approval and sign a contractor by the end of 2024. If all goes according to schedule, the upgraded WWTP will be fully operational and discharging treated effluent by 2026.
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
