Coastal Blue Carbon Opportunity Assessment for Snohomish Estuary: The Climate Benefits of Estuary Restoration
This landmark report demonstrates the carbon sequestration benefits of restoring tidal wetlands in the Snohomish estuary in Puget Sound, Wash. The report was prepared by Restore America’s Estuaries, Ecological Science Associates (ESA), Western Washington University, and EarthCorps. Lead funding for the study was provided by NOAA’s Office of Habitat Conservation. The Boeing Company and the Wildlife Forever Fund provided additional financial support.
The purpose of this report is to: (1) inform policy makers of the scale of GHG emissions and removals associated with management of coastal lowlands under conditions of climate change; and (2) identify information needs for future scientific investigation to improve quantification of GHG fluxes with coastal wetlands management.
The Snohomish Estuary was selected as a system representative of the wider Puget Sound and Pacific Northwest Region in terms of geomorphology, land use, and management issues. The historic estuary, the second largest in Puget Sound, consisted of a suite of forested wetlands, scrub-shrub wetlands, and emergent tidal wetlands. Clearing and draining the wetlands resulted in subsidence of organic soils. Today the subsided lands include agriculture (lowered water table), anthropogenic Palustrine wetlands (high water table), and a small area of planted forest. Soils are a mix of organic and mineral materials. The estuary hosts remnant emergent and forested wetlands; an example of a large-scale regenerating wetland, North Ebey Island, breached in the 1960s; and drained wetland soils under various forms of management.