Lower Nooksack River Restoration

As a subconsultant, The Watershed Company conducted an assessment of the Lower Nooksack River and led an alternatives analysis to help Whatcom County restore the area’s tidal habitat and reduce flooding impacts to nearby roads and neighborhoods. Once a forested estuary, early 20th century agricultural development and levee construction channelized the river’s mainstem, resulting in the loss of historic tidal wetlands and salmonid and waterfowl habitat.

Weighing input from a diverse group of tribe, agency, and community stakeholders, The Watershed Company staff classified existing and proposed conditions in terms of flood risk, habitat for focal species, water quality, and land use. Using a combination of hydraulic modeling and GIS, our staff then developed a process to design and evaluate restoration alternatives relative to changes in these conditions. We analyzed the output relative to existing ground surface elevations, mapped infrastructure, and habitat benefits, which we characterized using a Habitat Equivalency Analysis (HEA).

The alternatives analysis, completed in 2015, led to federal authorization of $261 million in 2016. This funding will support the full suite of restoration actions included in the preferred alternative, including parcel acquisition, levee setbacks, tidal restoration, and bridge modification and replacement. Completion of the project will restore approximately 1,800 acres of freshwater tidal marshes, accomplishing 25% of the Puget Sound Action Agenda’s 2020 estuarine habitat recovery target.

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