The completion of a three-year feasibility study has further solidified efforts to remove Enloe Dam and restore access to the Similkameen River for native salmon species.
A wooden dam on the river was built in 1906 to generate electricity, about 5.6 kilometres west of Oroville in Washington State, before it was replaced in 1920 with the concrete structure that still exists today.
The dam has not produced electricity in almost 70 years, since 1958. The Lower Similkameen Indian Band were the first to pass resolutions calling for the dam’s removal in 2015, followed by the Confederated Tribes of the Colville Reservation (CTCR) and the Upper Similkameen Indian Band.
Trout Unlimited and the CTCR secured the funding and hired the firm Stantec Consulting Services to complete the feasibility study in 2023, with it finished and released in 2026. Trout Unlimited announced the milestone with a blog post on their website to share the news.
“The completion of the feasibility study is an important milestone in the process of evaluating the future of Enloe Dam and the Upper Columbia’s struggling populations of steelhead and spring Chinook,” Micheal Ward, Trout Unlimited’s North Central Washington senior project manager, was quoted as saying in the blog post. “The work isn’t over. We’ll keep working closely with our partners to find a collaborative solution that benefits fish and regional communities.”
The removal of the dam would restore access for salmon to the Similkameen River in an area covering more than 2,400 kilometres (1,500 miles), with the lowest estimates for costs starting around $26 million USD. The most expensive options, which would dredge much more of the reservoir behind the dam and cost up to an estimated $210 million USD.
The study compared the project’s cost estimate with recent dam removal projects, many of which were also undertaken to restore access for native species.
The other projects included the removal of four dams on the Klamath River, opening up 676 km (420 miles) of habitat at a cost of $450 million USD; the removal of two dams on the Elwha River, opening up 112 km (70 miles) of habitat for $325 million; and the removal of the Condit Dam on the White Salmon River, which opened up 53 km (33 miles) for $32 million.
Based on the affordable options, as outlined in the study, costs between $31 and $35 million USD would be an entire magnitude more cost-effective considering the amount of habitat re-opened per dollar spent.
All but one of the studied options would see the dam site returned as close as possible to its original conditions, with the hydropower infrastructure removed, the built-up sediment managed, and native plants restored to the area. One option, leaving the project
The project would also include restoration work at the nearby Coyote Falls cultural site, which was excavated during construction of the dam’s Hagerty Ditch. The falls are referenced in the Syilx peoples’ captikʷł1, a collection of teachings about Syilx Okanagan laws, customs, values, governance structures and principles that still serve as reminders and instruction for the nations today.
The differences between the options studied, outside of the one where nothing is done to remove the dam, were all related to what and how much sediment would be removed from decades of accumulation in the resevoir behind the dam.
One of the concerns with the removal of the dam is the risks the fine-grained sediments pose to native species if released, due to their volume and the potential for arsenic contamination.
In addition to the costs for removing the dam, the feasibility study included estimates for the amount of money saved by the structure’s current owners over the next 50 years, which could range between $4.2 million USD and $17.6 million USD, depending on what repairs are made during that period.
Beyond restoring salmon access to traditional habitat, the study says the project could also bring regional benefits, including improved recreational opportunities, increased tourism spending and the potential future harvest of salmon once populations recover.
With the study complete, the next steps include determining how to address sediment behind the dam, securing regulatory approvals and permits, negotiating easements or other agreements, and seeking funding for the project.
The full study, background resources, and information on the next steps for the project including public participation can be found at: www.enloefeasibilityassessment.com/