Ravenswood salt pond improvements take shape

After years of planning, an effort to transform a nearly 300-acre salt pond into the tidal marsh that once lined the shore is finally taking off. Planners are preparing for dirt hauls to the area south of Bedwell Bayfront Park to begin this summer, said John Bourgeois, executive project manager of the South Bay Salt Pond Restoration Project. In planning for a range of projects at the site — including bolstering a levee on the pond’s inland edge, reintroducing tidal marsh vegetation and making way for established salt pond and managed pond habitats in adjacent ponds — Bourgeois described the restoration effort as a series of balancing acts.

“We’re changing the landscape at a pretty large scale, and so we want to be really cautious that we understand the implications of those changes and that we’re doing it the right way,” he said.

Among the many priorities the multi-agency team will be weighing is ensuring the snowy plover’s habitat is maintained while they create tidal marsh habitat for species like Ridgway’s rail, salt marsh harvest mouse and steelhead trout. They will also be working carefully around the edge of Bedwell Bayfront Park to prevent the former municipal landfill from being leached, which could release contaminants and affect water quality, said Bourgeois. And though they need a lot of dirt — to the tune of 300,000 cubic yards — they need clean dirt for the sensitive habitat they’re building and need to wait until excavations from construction sites across the Bay Area are tested before hauling them to the site, he explained.

“It’s this giant chess game of what makes the most sense on the landscape,” he said.

No small feat

As part of the Don Edwards San Francisco Bay National Wildlife Refuge, the cluster of seven Ravenswood salt ponds are adjacent to marsh lands at Greco Island just north of it, creating a stark border between the green vegetation covering Greco Island and the bright yellow and red hues of the salt pond. When the restoration project is complete, Bourgeois said some 300 acres of what is currently salt pond will resemble the marshland just north of it.

But to get from a salt pond to a tidal marsh habitat is no small feat, and will require some 30,000 trucks to ferry some 300,000 cubic yards of dirt to the site, said Bourgeois. The dirt will be used to raise and widen a levee on the inland edge of the 300-acre salt pond and create 15 acres of an upland transition zone between the new marsh and the park. It will fill ditches lining berms constructed by the salt company so water will flow through the land’s natural marsh channels when the berms are breached. Also included in the project will be the installation of water controls in adjacent ponds and channels to create a habitat where snowy plovers can nest as well as a deeper pond where shorebirds and waterfowl can live, said Bourgeois.

Long time coming

The effort to restore the tidal marsh habitat that preceded the ponds has slowly gained momentum over the years. Beginning in 2003, a collaboration between federal and state agencies enabled the purchase of more than 15,000 acres of salt ponds from Cargill Inc. and marked the start of the South Bay Salt Pond Restoration Project, which includes Bayfront salt ponds in San Mateo, Alameda and Santa Clara counties. The acquisition turned the Ravenswood salt ponds over to the U.S. Fish and Wildlife Service, at which point they became part of the service’s Don Edwards San Francisco Bay National Wildlife Refuge.

Voters’ support of Measure AA — a $12 annual tax on every parcel aimed at generated a total of $500 million for restoration projects — on the June 2016 ballot provided projects like the one planned at the Ravenswood salt ponds the funding needed to make them a reality.

Though Ravenswood ponds may not be as large as some of the salt ponds being restored in Mountain View, Alviso and Alameda County as part of the South Bay Salt Pond Restoration Project, Bourgeois said they are unique in their close proximity to shoreline developments like the Facebook campus and the Dumbarton Bridge. So while a major goal of the project is to restore habitats for a variety of species, it is also aimed at bolstering flood protection measures for the nearby developments, said Jared Underwood, refuge manager with the Don Edwards San Francisco Bay National Wildlife Refuge, a division of the U.S. Fish and Wildlife Service.

Underwood said the U.S. Fish and Wildlife Service has borne the burden of maintaining the berms, which had been built by the salt company years ago, since the Ravenswood ponds were turned over in 2003. He looked to the bolstered levee and creation of new tidal marsh, which can absorb surges of water during storms and waves, to better protect the infrastructure behind the ponds.

“As part of this project, we’ll be improving these levees so that we can breach this and still protect all of the assets and infrastructure behind the pond,” he said.

Flood protection

Enhancing flood protection in the area is also expected to stem the effects of sea level rise, said Dave Pine, chair of the San Francisco Bay Restoration Authority. Also president of the San Mateo County Board of Supervisors, Pine said the combination of the projects funded by the authority, which voted to place Measure AA on the June 2016 ballot, are expected to create an wider ecological buffer and better flood protection in the face of rising seas.

“The hope is to get as many of these projects completed by [the mid-century] so that the natural ecosystem can hopefully stay at pace with some of the sea level rise,” he said. “But if we’re delayed, we’ll lose our opportunity to do restoration.”

Pine was hopeful about planners’ use of adaptive management, which involves testing hypotheses about how to best usher in ecosystems and boost flood protection, and applying them in other parts of the Bay. Of the $7.4 million the authority dedicated to the $15 million project, some $1.2 million is allocated toward scientific research, said Pine.

As trucks bring dirt to the site in the coming months, Bourgeois said some parts of the trails at the Bedwell Bayfront Park may be temporarily closed, and that closures would be marked at trailheads and updated on the U.S. Fish and Wildlife Service’s website. But with construction of a half-mile of new trail overlooking all three habitats and expected to connect with the Bay Trail, Bourgeois is hoping hikers will appreciate the public access and education opportunities the project will enable once complete.

“It’s going to be a really interesting place for the public to go and see the different types of restoration happening,” he said.

Visit fws.gov/refuge/don_edwards_san_francisco_bay/news/ravenswood.html for updated information on project progress and trail closures.

anna@smdailyjournal.com

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