This project represents the culmination of several years of thoughtful value engineering and preconstruction collaboration, ultimately paving the way for a new trap and haul fish passage facility in the tailrace of Cabinet Gorge Dam. Designed to support Bull Trout, listed as a Threatened species under the Endangered Species Act, the work required exceptional care, coordination, and respect for the surrounding natural environment.
Located at a remote hydroelectric site, the project demanded close partnership with the Federal Energy Regulatory Commission and additional permitting agencies. Because the new structure sits directly in the tailrace, our first major effort involved designing and installing a cofferdam. Slayden crews completed this critical milestone ahead of schedule during the initial construction season, setting a strong foundation for the work that followed.
Once dewatered, we moved into the heart of construction within the cofferdam. Our team excavated the rock riverbed and installed rock dowels, foundation anchors, dental concrete, and foundation grouting to establish a durable, long-lasting base. We then placed over 1,000 cubic yards of reinforced structural concrete, integrating hydraulic piping and electrical pathways directly into the structure. After concrete completion, Slayden installed six hydraulically operated slide gates, a vee trap, brail crowder and hoist, two fish counters, six PIT tag units, and a fish hopper, along with structural steel and miscellaneous metals.
Beyond the fishway itself, we constructed a steel building to support and protect the new monorail hoist and erected a pre engineered metal building to house the hydraulic power unit, programmable logic controller, and fish monitoring systems. We also installed a siphon intake system featuring two retrievable cylindrical fish screens, a control system, and an access platform anchored to the upstream face of the dam. This system delivers water to the fishway through two 36 inch diameter pipes, installed by carefully cutting through the dam, placing the new pipe penetrations, and restoring the structural section with reinforced concrete.
Slayden earned First Place in the 2025 AGC Construction Safety Excellence Awards (CSEA) in the Utility Infrastructure Category — Under 500,000 Work Hours.
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Slayden Constructors and Jacobs Engineering recently completed a $78 million expansion of the Robert A. Duff Water Treatment Plant for the Medford Water Commission. The project boosts capacity from 45 to 65 million gallons per day and adds advanced filtration, a new reservoir, a modern pump station, and seismic‑resilient redundancies. This upgrade strengthens long‑term water reliability for Medford and the greater Rogue Valley, supporting regional growth and public health.
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Slayden’s Jeff Wall recently achieved a unique milestone. At the Pacific Northwest Clean Water Association (PNCWA) conference in Spokane, Washington, Jeff became the first contractor to be chosen under the PNCWA to join the Select Society of Sanitary Sludge Shovelers, also known as the 5S society. Members are selected based on “outstanding, meritorious service above and beyond the call of duty.” As recognition for this achievement, Jeff received a one-of-a-kind -5S gold shovel award.
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