Round Butte Dam is located about 90 miles southeast of Portland, OR on and adjacent to the Warm Springs Reservation. Portland General Electric determined that a selective water withdrawal and fish bypass structure was necessary to ensure the survival of Summer Steelhead and Spring Chinook Salmon in the Upper Deschutes, Metolius and Crooked rivers. Partially due to unusual currents in Lake Billy Chinook, the downstream fish passage facilities constructed in the 1960’s failed to work properly.
The new system will be a 270 foot structure delivered to the site in pieces and assembled in and on the water. Associated Underwater Services will provide the underwater assembly and installation, topside support and underwater survey and inspection.
AUS will be using the long range Falcon “Sea Eye” with sonar capabilites, as pictured above, to guide and monitor the underwater activities. Barnard Construction is the general contractor, assisted by Dix Corporation. The project will take 3 years and involve drilling and grouting 11 piles 50 feet into the lake bottom, 320 feet below the water surface. The steel structure to be installed is made up of 3 parts. A Selective Water Bottom Structure will be submerged to 270 feet deep and attached to the existing powerhouse intake. A floating Selective Water Top Structure will be positioned directly above the Bottom Structure and connected by the 40 foot diameter Vertical Steel Conduit.
This new structure is designed to draw water in a more natural way to attract fish that will then be screened and released downstream on their way to the Pacific Ocean. Pictures of the actual construction shown include an overview of the site and the structure that will be used to lower the Selective Water Bottom Structure. The red iron is the lift barge, the black iron is the permanent pile structure that gets lowered to the bottom.