Smith Island Restoration

Location: Snohomish County, WA

Otak led the design, prepared construction documents, and supported the permitting for this project to restore tidal influence to 328 acres of the Snohomish River Estuary, providing for long-term conservation of tidal wetland functions. Work included design and construction documents for 5,600 feet of a setback levee, hydrologic and hydraulic modeling and design of drainage facilities for properties landward of the setback levee, hydraulic modeling of tidally influenced riverine flooding of the restoration area, and design of restoration features including engineered log jams and new tidal channels. The restoration design includes grading down 4,500 LF of existing perimeter dike, 13 excavated tidal channels, eight engineered large wood structures, and two additional engineered large wood revetments for stabilization of the banks of the existing dike to restore salmonid habitat and promote diversity in vegetative establishment. The project will also breach and remove remnant dikes, remove agricultural drainage features, install drainage pipes and check valves, a stormwater pump station, and a public parking area. The work was contracted as two separate construction packages. The first phase included the setback dike, pump station, and drainage pipes for interior stormwater management. The second phase included constructing estuary restoration features, breaching the existing dike, and coordination with the City of Everett and restoration work within the City’s corporate limits.