Coho Creek Wetland and Stream Assessment and Enhancement
Restoration of 1.5 miles of stream and associated wetlands on a former Boeing test site is providing salmonids with habitat. Since the restoration, several hundred mass-spawning chum salmon, Coho salmon, and cutthroat trout have returned to Coho Creek to spawn.
The Watershed Company assessed the 700-acre site adjacent to The Tulalip Tribes’ entertainment facilities north of Seattle, and prepared design and construction documents to restore and enhance the creek. The design relocated the creek from a ditch-like channel into a meandering channel with pools, riffles, habitat structures, a floodplain, and native vegetation. Work included excavation of 47,000 cubic yards of material. The design also incorporated enhancement work previously accomplished by the Tribes. Analysis of stream flow took into account future stormwater treatment facilities and the Tribes’ Membrane Wastewater Treatment Plant discharge.