Smith Island Estuary Restoration Snohomish County, Washington

The Smith Island estuary restoration is one of the largest efforts of its kind. By removing agricultural levees and dikes—thereby reconnecting Union Slough’s historic tidal marshlands—Snohomish County created more than 300 acres of habitat for endangered Puget Sound salmon and secured the long-term well-being of its local farmers, communities, and infrastructure.

Restoring a Wetland to Expand Endangered Species Habitat and Improve Community Infrastructure

Restoration efforts involved close collaboration with a multi-agency coalition of county, state, federal, tribal, and local stakeholders to design, permit, and prepare the construction documents for this large-scale restoration project, located near Interstate 5 outside the city of Everett. The Otak-designed improvements addressed concerns related to interior drainage, saltwater intrusion, and flood protection, as well as the protection of a nearby liquified natural gas pipeline. Specific elements include safe breaching and removal of remnant dikes and agricultural drainage features, along with the installation of drainage pipes and check valves, a stormwater pump station, and a public parking area. The restored estuarial wetlands include five types of tidal channels and four types of wood structures and rock revetment for scour protection.