Municipal and utilities

Upper Baker Dam floating surface collector

Location: Concrete
General contractor: Natt McDougall Co.
Owner/developer: Puget Sound Energy
Engineer: URS Corp.
Contract amount: $25 million

Photo courtesy of Natt McDoughall Co.
Natt McDougall Co. built a fish collection system that transports migrating salmon around the Baker Dam.

The Upper Baker Dam floating surface collector is a first-of-its-kind fish collection system that intercepts downstream migrating sockeye salmon and transports them around the Baker Dam, returning salmon runs to the Skagit and Baker rivers.

The floating surface collector includes a 130-by-60-foot, 1,000-ton barge, which contains fish screens, screen cleaners, baffles, pumps, holding ponds, two control houses, a fish evaluation area, a pit tag detector for tracing fish and a monorail crane for loading captured fish.

The collector was installed in 280 feet of water, and the McDougall team attached to it a net transition structure — a 75-foot-high, 130-ton steel framework whose main structure hangs down below the water.

A support sled was engineered and fabricated out of structural steel to provide support to the net transition structure during erection, and a four-rail launch ramp was installed on the reservoir bottom. The structure was erected atop this sled and launched down the tracks into the water.

In 2008, fish collection system’s first year of operation, more than 300,000 fish were recovered — the most ever to migrate past Upper Baker Dam.

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