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Wetland and aquatic improvements at Grass Creek

Why is WSDOT providing mitigation?
Construction update
What are the ecological benefits of the mitigation project? 
What is the project timeline?

We are providing improvements to wetland and aquatic resources at Grass Creek in Grays Harbor County.

Vicinity map of the Grass Creek mitigation site

Why is WSDOT providing mitigation?


Through the environmental review process, WSDOT works to avoid, minimize and mitigate for all environmental effects. While we have avoided and minimized to the greatest practical extent, construction of the casting basin and launch channel resulted in the loss of approximately one acre of wetlands, as well as shoreline and fish habitat effects. To mitigate for this, WSDOT is providing improvements at the Grass Creek site.

Construction update

WSDOT awarded a contract to Rognlin’s Inc. of Aberdeen to remove portions of an earthen dike on the 68-acre Grass Creek site. Work started in summer 2011, reconnecting tidal channels and restoring the natural tidal influence to the site. The work at Grass Creek restores and protects a variety of wetlands and shoreline habitats, mitigating environmental stress caused by the Pontoon Construction Project.   

What does the Grass Creek site look like today?


Tidal exchange in a created mudflat at the Grass Creek mitigation site.



WSDOT crews observe the removed berm along Grass Creek.

What are the ecological benefits of the mitigation project? 

The Grass Creek mitigation site will support a variety of plants and wildlife that thrive in wetlands, salt marshes and mudflats. Native fish include staghorn sculpin, bull trout, longfin smelt and shiner perch. Wildfowl include great blue heron, mallard, song sparrow and bald eagle.

The restored tidal channels will provide habitat for migrating salmon. Native plants and organic soils will improve water quality and benefit the on-land and in-water environments.

This mitigation directly and indirectly benefits the environmental health of the larger Grays Harbor watershed area. The Grass Creek site provides a good ecological fit with project effects and has the highest likelihood of success, based on the property’s location and characteristics.

What is the project timeline?

Work started in summer 2011 and is now substantially complete, and WSDOT will maintain and monitor the site until 2022. The Grass Creek site will provide approximately 45 acres of potential mitigation area that could be used for future WSDOT projects.