Landing at SFO can be a pretty, if sometimes harrowing experience (short runway). A nice distraction: The salt marshes that form a quilt of various umbers around the southern part of SF Bay. More than an interesting sight, such marshes might be a crucial, natural solution to the sea level rise that threatens our region.
Earlier this month, the San Francisco Planning commission announced its Sea Level Rise Action Plan amid projections of rising oceans: Up to 1.4 meters by 2100. In the wake of that rise would be everything from schools and hospitals to airports and tech campuses. Research published in Nature shows San Mateo is particularly at risk.
“If we choose not to act on the real threats of sea level rise, we are choosing to put some of the most socially and economically vulnerable communities, and some of its most valuable real estate, at significant risk," says John Rahaim, Director of San Francisco Planning. As Gil Kelley, the Planning Department’s director of citywide planning, added for the Chronicle, "The plan doesn’t propose specific programs and solutions. It’s a call to get those programs in place... Ultimately, we’re going to need large fixes."
As Scientific American discusses, the muddy marshlands surrounding the Bay might represent one such "large" fix. "Besides being a biodiversity hotspot, marshes are cheap and effective insurance," Scientific American writes. "They are natural, resilient buffers against rising water. They dissipate the wave energy, absorb tidal waters like a sponge, and slowly release the water back into the bay... a restored marshland is a promising front line armor."
The South Bay Salt Pond Restoration Project, which under Senator Dianne Feinstein's leadership since 2003 has been at work converting an area larger than Manhattan back into tidal marshlands, provides one salient example of developing marshland as buffer. But for that project to succeed, it needs more mud. 53 million cubic meters of sediment just to kickstart tidal restoration, to be exact. "Sediment is critical to wetland," said Letitia Grenier, the lead scientist on a 2015 report about climate change and the bay. "It means life." As Scientific American elaborates,
"Marshes depend on mud. Once the levees are breached, the tides wash in mud, twice a day, day after day. This mud brings nutrients. Then, with the addition of light and carbon dioxide, a chain of events sets off in the estuary. First, phytoplankton like cyanobacteria and green algae spread through the muddy waters. Krill drift around and feed on the phytoplankton. Snails, shellfish, California bay shrimp and worms eat up the mud they live in. Shorebirds like avocets, willets and godwit swoop in and dig their beaks deep in the mud for the worms. Striped bass and the chinook salmon swim in and out to feed on worms and crustaceans. Over the years, peregrine falcons and leopard sharks start to hang out at levee breaches for the smaller fish and birds. When there's enough sediment, the plants will start growing. Endangered species like the salt marsh harvest mice and Ridgway's rail start foraging around the marsh. Marshland is born again, ever eager for more mud."
How to get that mud cycle going, then? Get more of it, which will lead to more sediment on its own. But so far, we've just gotten rid of the stuff. Where once about 200,000 acres of marsh lay, Gold and Silver Rush-era miners began diking the marshes to produce salt in hopes of refining mined ore. Agriculture and development also depleted marshland.
To replace what's been lost, enter "dirt brokers." Says John Bourgeois, executive manager of the restoration project, #8220;There's a lot of dirt in the market now,” said John Bourgeois, the restoration project’s executive manager. That could include dirt from development projects and more, but so far the Salt Pond Restoration Project has used little recycled mud.
Further, even once you've got the dirt in hand, depositing it in the marshland is tricky. Bares can't get close and bulldozers alone can't help.
For now, the marshes remain beautiful — striking enough to inspire retired UC Berkeley professor Cris Benton to publish birds-eye images in Saltscapes: The Kite Aerial Photography of Cris Benton, in 2013. But surely Benton — and we, too — could use a little more marsh to work with.