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Coho Creek Wetland and Stream Assessment and Enhancement Plan

Conceptual design options for the re-alignment of Coho Creek.
Ditch-like segment of Coho Creek planned for re-alignment.
Cutthroat trout captured during a stream survey along Coho Creek.
Crews inspect segment of Coho Creek during the design phase.

Statistics

Client: Tulalip Tribes
Location:
Dates: 2005-2007
Services: Stream restoration design, construction monitoring

Description

The Tulalip Tribes Environmental Department retained The Watershed Company to prepare designs and construction documents to restore and enhance about 11,500 feet of Coho Creek on the 700-acre, former Boeing Tulalip Test Site. Several hundred mass-spawning chum salmon in addition to scores of coho salmon and cutthroat trout have returned to Coho Creek annually to spawn in recent years.

The primary purpose of the restoration is to move the creek from its existing ditch-like channel into a new meandering channel with pools, riffles, habitat structures, a functioning floodplain, and associated native riparian/ wetland habitats. The design incorporates previous enhancement work already accomplished by the Tribes. Existing stream flows will be augmented by integrating future stormwater treatment facilities and discharges through the use of wastewater from the Tribe's Membrane Wastewater Treatment Plant. An estimated 47,000 cubic yards of material will be excavated from the proposed new channel alignment for Coho Creek.