Building Coastal Resilience
Without restoration, Elkhorn Slough’s marshes are projected to drown within 50 years due to sea level rise. The Tidal Wetland Program gives our salt marshes a fighting chance.
The project is currently in Phase III, which includes restoration of a 30-acre section of degraded marsh at Seal Bend, eelgrass transplants, oyster aquaculture, and restoration of an additional five acres of perennial grasslands adjacent to Phase I. Phase I and II included 90 acres of marsh adjacent to Yampah Island.
In 2021, we applied for NOAA drought funding to better understand the ecological impacts of drought on Elkhorn’s tidal marsh ecosystem and to see if this was the reason we were getting less than expected marsh recruitment in our newly restored marsh. We added irrigation systems to small areas of the marsh to see if watering through the critical warmer and dryer season would mitigate drought impacts. Since then, we have had a great rain year and lots of new recruitment, but we anticipate we will still get some valuable information this summer with the help of our summer interns and graduate students.
Led by Elkhorn Slough Reserve’s Tidal Wetland Program, the Hester Marsh restoration project is guided by input from more than 100 scientific advisors, environmental regulators, and community members.
The objectives of this project are to significantly increase high-elevation tidal marsh, native-dominated grassland, and native oyster habitat, as well as to engage a number of community groups including local Native American tribal members and the broader coastal management community. The project will restore about 122 acres of tidal marsh using roughly 500,000 cubic yards of soil beneficially-sourced from the Pajaro Bench Excavation Project and the hillside of a local farm impacted by saltwater intrusion. The project also includes 35 acres of native-dominated grasslands while increasing eelgrass and oyster habitat sub-tidally.
This innovative, integrated approach to coastal restoration is being scientifically-designed and monitored so that lessons learned can be shared broadly with other coastal managers.
Funding for this project was provided by the California Department of Fish and Wildlife’s Wetlands Restoration for Greenhouse Gas Reduction Program, a statewide program that puts Cap-and-Trade dollars to work reducing greenhouse gas emissions; the California State Coastal Conservancy; the California Department of Water Resources Integrated Water Resource Management Program; the Wildlife Conservation Board; and the US Fish & Wildlife Service National Coastal Wetlands Conservation Program.
Over the past centuries, the coastal landscapes around this estuary have been highly altered, with habitat lost to diking. Iconic species such as pickleweed, eelgrass, and oysters play vital roles in supporting fish, birds, and sea otters, as well as in taking up carbon dioxide and pollutants. Bringing back these species is critical because they each form the foundation of a distinctive coastal habitat, thereby enabling us to bump the system back into balance.
Salt marsh will be returned to an area where it was lost due to diking. Dikes cut off tidal waters, the lifeblood of salt marsh habitat, and led to soils drying out and sinking too low for marsh to grow after the dikes were breached. To reverse this, soil is being scraped from a nearby fallowed farm to raise the elevation high enough to support marsh and last through moderate sea-level rise.
Eelgrass, which grows in meadows beneath the tides, will be restored by taking plugs from dense existing beds and bringing them into the newly restored, unvegetated tidal creeks of the marsh restoration area.
Oysters in Elkhorn Slough are at dire risk of local extinction, with no successful reproduction in the wild since 2012. To restore these vanishing filter feeders, scientists will bring adult oysters from the slough to an aquaculture facility at Moss Landing Marine Labs. Baby oysters will be reintroduced to the restored tidal creeks.
Photo by Jim York