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March 16, 2018
Kiewit Infrastructure West Co. will build what the Army Corps of Engineers calls the largest trap-and-haul fish passage facility in the nation.
The corps awarded a $112 million firm fixed-price contract on Wednesday to Kiewit for the project at Mud Mountain Dam near Enumclaw. Kiewit's schedule calls for completion by December 2020.
“The contractor's ability to quickly construct an operational facility was one of the primary evaluation criteria,” said Leah Hauenstein, senior project manager at the corps' Seattle District, in a news release. “We expect mobilization for construction to begin in May.”
The release said the corps is going with an aggressive schedule to minimize risk to fish.
According to the corps, 16,271 White River chinook were counted last year, the largest fish run in 72 years of record keeping. That was attributed to operational changes at the dam for smolt traveling down the river. Other fish species also ply the river.
The fish facility will be built adjacent to an existing hatchery on the White River that is owned by the Muckleshoot Indian Tribe.
Fish will swim through five gates leading to an entrance pool, then travel up a fish ladder with 10 pools to two presort holding ponds. From there, fish will travel through two augers to a distribution/sort flume where they will get loaded into a truck or moved to the tribe's broodstock collection or monitored.
Trucks will take the fish upstream of the dam, where they will be released into the river through a flume.
Trucks that can haul 4,500 gallons of water will be used to transport up to 60,000 fish in one day. Dam operators currently use 1,200-gallon-capacity trucks, which will be retained as part of the new fleet.
The design team for the project involved more than 150 corps employees from three districts, and staff from HDR and Tetra Tech. The Muckleshoots, Cascade Water Alliance and National Marine Fisheries Service also collaborated on the design.
Mud Mountain Dam is an earthen, rock-filled structure built by the corps in 1948 for flood risk management, which also provides for fish passage. Its existing trap-and-haul facility doesn't meet modern standards.