Elkhorn Slough, a coastal wetland visible from the Highway 1 bridge in Moss Landing, CA is a breeding ground for many ocean species and a safe haven and food source for sea otters and other marine organisms. This wetland is a rich ecosystem with a diverse group of species and complex food webs. More than 340 species of resident and migratory birds use Elkhorn Slough as a vital habitat, including over 20,000 shorebirds annually.
The entire waterway of Elkhorn Slough up to mean high tide is part of Monterey Bay National Marine Sanctuary’s 6,094 square miles of federally protected area. The slough starts 7 miles inland at Carneros Creek and empties into Moss Landing Harbor and the head of the Monterey Canyon. NOAA’s National Estuarine Research Reserve system, California Department of Fish and Wildlife and the California’s State marine protected areas (MPAs) also provide additional protection of this natural resource.
For millennia, Elkhorn Slough had been dominated by salt marsh, punctuated by meandering tidal creeks that harbored oyster beds harvested by Indigenous people. After colonization, many marshes were diked, farmed and the soil was compacted, sinking and dramatically altering the slough. Creation of the Moss Landing Harbor in 1946 caused tidal erosion removing even more marsh habitat. The slough is vulnerable to sea level rise as well, and without restoration, these vital marshes could become submerged in salt water, turning them into mudflats within 50 years.
Recently, Elkhorn Slough Reserve’s Tidal Wetland Program has been actively working to restore an area of the slough known as Hester Marsh. This project has been guided by input from more than 100 scientific advisors, environmental regulators, and community members, including local Native American tribal members.
“We are grateful to the Native Stewards of the Amah Mutsun Land Trust, who worked hard on behalf of their ancestral lands, getting knee high in the mud to restore oyster populations,” says Kerstin Wasson, research coordinator for NOAA’s Elkhorn Slough National Estuarine Research Reserve.
The Hester Marsh Project significantly increased the amount of high-elevation tidal marsh by trucking in and bulldozing 500,000 cubic yards of soil beneficially-sourced from the Pajaro Bench Excavation Project and the hillside of a local farm. This herculean effort resulted in restoring 120 acres of native-dominated eelgrass, pickleweed and grassland vegetation.
The Hester Marsh project has also resulted in many wildlife benefits. Wild oysters have been thriving in the area for the first time in over a decade, and sea otters are using the area for hauling out, resting and sleeping on the pickleweed. There have been raccoon, coyote, skunk traversing the area and migratory birds roosting, along with local fish and crab communities starting to thrive again.
Wasson reflects on the successful restoration, “This project provided a remarkable opportunity to meld restoration with science. We’ve incorporated large-scale experiments into all our restoration, with Elkhorn Slough Reserve staff collaborating with students and other researchers to design and monitor studies. What we have learned will help improve restoration at the slough and estuaries elsewhere.”
In 2023, a study led by researchers at the Monterey Bay Aquarium and Middlebury Institute of International Studies’ Center for the Blue Economy found that sea otters attract recreational visitors to Elkhorn Slough, generating more than $3 million in revenue to the local community. This “Otternomics” effect shows otters are key to eco-tourism, attracting visitors who spend money on food, lodging, rentals and tours.
Hester Marsh restoration project is a win-win for science, stewardship and resource protection. By reversing wetland marsh loss, the project not only enhances habitat for species like sea otters and builds resilience against sea-level rise, but also provides valuable ecosystem services like improving water quality and sequestering carbon, which are crucial benefits human receive from healthy natural systems. And to boot, the science conducted during this project inform the best methods to use for future restoration projects around the world.
Lisa Uttal is a marine biologist and media coordinator for NOAA’s Monterey Bay National Marine Sanctuary. The organization conducts research, education and resource protection in one of most biodiverse marine protected areas in the world.
