Can the San Francisco Bay Be Saved From the Sea?

A massive wetlands-restoration effort aims to protect wildlife, people, and real estate from the worst effects of climate change.

Researchers stand near water from a former industrial salt pond as it flows into the San Francisco Bay
Noah Berger / AP

“The scale of what we are proposing to do out here scares people,” says John Bourgeois, the executive project manager of the South Bay Salt Pond Restoration Project, the single largest wetlands rehabilitation effort this side of the Mississippi River. Bourgeois and I are standing in the Don Edwards San Francisco Bay National Wildlife Refuge Environmental Education Center in a glass-walled widow’s walk. To the west is the tiny, working-class town of Alviso. Just beyond it spreads Silicon Valley, its hunger turning earth to glass. Together we look out over the trailers and the former canneries, over the shimmering tech campuses—Dell, Google, and Microsoft—and the slow slope of the nearest landfill.

This post is adapted from Rush’s upcoming book.

Filling the foreground are the former salt ponds from which the project takes its name. Today, some of the ponds are open water, while others are covered in a green patchwork of pickleweed and bulrushes. Most haven’t been used to make salt for well over a decade. Weeks of heavy rain have left the earthen embankments that divide one pond from the next so unstable that they can’t support the weight of Bourgeois’s Prius. “We’re going to have to walk instead,” he says.

Bourgeois was born, raised, and educated in Lafayette, Louisiana, a place where wetlands define daily life, even as they disintegrate. “I used to have to drive two hours to get to the boat launch, then motor the boat an hour and a half just to arrive at my old project site,” he says. “When I came to San Francisco Bay, I was like, ‘Where are all the wetlands?’ I couldn’t believe I was looking at the biggest estuary on the West Coast.”

Reach back 200 years, and the scene before us would be wholly different. The levees, the open water, and the mauve tint of microbial activity in the few still-functioning salt ponds would all be gone. Imagine instead a sea of grasses in all shades of green, from rich emerald to the misty gray of tule and fog, from honeyed lime into the blown-out colors of dried papyrus. Willow trees would be flourishing along freshwater creeks, a ribbon of spotted sandpipers in from South America fluttering over the mudflats. If you can imagine this, then you can at least partially imagine what Bourgeois is trying to bring back.

While the indigenous people of California used the southern spur of the bay to produce salt, it wasn’t until the 1850s, when non-Native, family-run operations began to sprout up, that the tidelands were dramatically transformed. Salt was a hot commodity, vital for both the preservation of food and the mining process that drove hundreds of thousands of prospectors to the Sierra Nevada. So fierce was the demand that local “salt makers” began to alter the bay’s low-lying areas in an attempt to speed up production. They paid laborers to heap dirt along the bayside edges of the mudflats, restricting tidal flow and accelerating evaporation rates. Levee after levee went in, and the rhythmic rise and fall of the bay water through the mudflats and marshes ceased. Over time, Leslie Salt Works took control of each of these relatively small-scale outfits, acquiring one salt farm after another until it owned over 40,000 acres, an area equal in size to around three Manhattans, on the east and west flanks of the South Bay.

In 2003 the state of California purchased many of these salt ponds from Cargill, Leslie’s successor, paving the way for the most innovative and forward-looking wetlands restoration effort in the country. Since then the project area has grown in size, and today it encompasses about 15,000 acres. The project’s staggering size, and its reliable state funding, enables Bourgeois and his team to experiment with landscape-scale interventions that have never before been attempted. At least not in coastal wetlands. And not with the express purpose of trying to bring back what has been lost—while also readying it for a future we don’t really understand.

The night before I visit the South Bay Salt Pond Restoration Project, I stop by the Exploratorium. It is Monday and the museum is closed, but I have arranged for a private viewing of the museum’s Fisher Bay Observatory. Susan Schwartzenberg, the curator, greets me at the entrance and we walk together out the length of the building and into the Observatory itself, which is cantilevered out over the Bay. A car-size topographical map of the region sits in the center of the room. Filtered blue light is projected over the miniaturized landmass, indicating the current shape of the shoreline. “This is where we invite folks to think about sea-level rise,” Schwartzenberg says, turning a knob at the base of the exhibit. But she doesn’t spin it forward, moving the projection into the future; instead, she pulls the projection backward through time. “This is 18,000 years ago,” she says. Back then much of North America was covered in a massive sheet of ice. Sea levels were about 300 feet lower, and the Bay Area’s telltale kidney-shaped bodies of water were almost nonexistent. She slowly turns the knob forward and the projection travels toward the present. There is little variation in the shape of the shore for roughly 5,000 years, then all at once it changes, the ocean rapidly covering up a significant area of dry land.

“Wait,” I say. “Can you go back?”

Schwartzenberg obliges and I watch the water pull away. Then she spins the dial again and the ocean throbs inland. I ask her to show me the transition once more, but this time I don’t watch the water—I watch the key to the map instead. Just as I suspected, the jump occurs about 13,000 years ago, during the event glaciologists have labeled Meltwater pulse 1A. During Meltwater pulse 1A, sea levels rose roughly 50 feet over three short centuries. The near-biblical rise in the height of the ocean is directly correlated to the melting of polar ice and the process of deglaciation, the very events that we have begun to witness at the planet’s northern and southernmost reach. Geologists often point to Meltwater pulse 1A as proof that that sea levels, when they change, tend to do so abruptly and with great speed.

Schwartzenberg moves the map into the present, and the colors of the shoreline shift. Any area that once was bay and has been filled is a deep, conifer-colored green. Roads are pink and airports are orange. As she turns up the water levels—adding one foot of rise, then two and three, four, and five—big sections of the city begin to disappear beneath the blue light. Anywhere that once was wetland slips beneath the surface of the Bay.

“It’s totally freaky to see that with just two feet you have lost two airports. Pretty soon all of the approaches to all of the bridges are gone, most of Highway 101 and Route 37, and healthy chunks of the 80,” Schwartzenberg says. The few current pockets of affordability—Alviso, Redwood City, Fremont, Richmond, and East Palo Alto—are all underwater, as are portions of Oakland, Marin County, and downtown San Francisco. What we think of as the coastline is a blur. Looking over the map, I wonder whether the Fisher Bay Observatory is designed to get visitors not just to think about sea-level rise but to begin to imagine the unthinkable: the unsettling of the American shore.

The next afternoon, on the northernmost edge of Alviso, John Bourgeois and I walk along the flat crest of an earthen levee. Much of the town has subsided significantly over the past century, thanks to the groundwater extraction necessary to support water-hungry crops like peaches and almonds. Together we peer into the hollow second story of the former Bayside Canning Company, with its radiant archways and hand-painted murals of women with long black braids carrying fruit to the production line. My gaze rests on the roof gable of a residential home just beyond the ruin. “They might make good candidates for relocation,” I say. If I look left, I am standing five feet above the bay; if I look right, I can peer into this attic.

Bourgeois ignores my comment. “The entire town is 16 feet below sea level,” he says, shaking his head.

To return tidal flow to the area, he has to remove the earthen embankments that separate the ponds from the bay. But before he does that he has to build a four-mile-long replacement levee running all the way from Baylands Park, around Alviso, and over to the Newby Island landfill, for flood protection. “The U.S. Army Corps of Engineers came up with a recommended levee height of 12.5 feet, but their estimate didn’t take sea-level rise into account.” Bourgeois pauses and gives me a look of exasperation. “My employer, the California Coastal Conservancy, and the Santa Clara Valley Water District decided to band together and pay the additional $16 million it would cost to make the levees sea-level-rise ready. That means going up a couple extra feet and making them considerably wider as well.”

Considerably wider is a bit of an understatement: Some of the levees Bourgeois has in mind will be more than 1,000 feet across, wide enough to increase topographical diversity in a landscape that currently has very little. “We need the width to build in transition-zone habitat,” he says. “Come down here during king tide, and you’ll find hawks cruising the levees, picking off endangered species. In the future it’s only going to get worse, the breeding and foraging habitats of these animals squeezed between the sea and the surrounding communities.”

The more Bourgeois speaks about these nearly horizontal levees, the more excited he gets. The current goal of the South Bay Salt Pond Restoration Project is to restore as much wetlands habitat as possible before 2030, when sea-level rise is expected to accelerate significantly, and to line, wherever possible, the upland edge with horizontal levees. Bourgeois hopes that they will give the tidal marsh the chance, at least in the short term, to migrate up and in. Oro Loma, a sanitary district in the North Bay that has invested heavily in shoreline restoration and protection, has already built a horizontal levee, and Bourgeois is gathering the raw materials for more.

“I even have a dirt broker,” he continues. “Silicon Valley is booming again, people are building like crazy. That’s a lot of dirt, and a lot of that dirt ends up in landfills. But now, instead of paying the landfill to dispose of it, construction teams are giving it to Pacific State [a local aggregate supplier], which tracks the material, tests it, and brings it to us. We’re getting 2 million cubic yards of fill—clean, confirmed, compacted—placed exactly where I want it, for free.”

As I listen to Bourgeois speak, I realize that I have been thinking about Alviso from a distinctly human point of view. I have been imagining myself standing behind the levee, waiting for the water to rush in. Bourgeois, on the other hand, looks at Alviso from the perspective of its wetlands. He is concerned less with human communities and our ability to adapt—we can and we will, he says—and more with how to keep the 50 percent of endangered and threatened species endemic to North America’s wetlands from going extinct. His priorities are to protect the salt-marsh harvest mouse and the California Ridgway’s rail living among the pickleweed and bull grass. And if that also buys Alviso more time, all the better.

Everywhere I look in the South Bay, I see another set of human interventions intended to mimic a healthy tidal landscape. On the one hand, the tremendous effort that has gone into restoring and readying these wetlands for sea-level rise strikes me as both unprecedented and wise; on the other, it all seems like too much somehow, yet another example of first-world exceptionalism and the delusion that we can design our way out of the planetwide geophysical transformation we’ve set in motion.

“Over the last 150 years we’ve changed the shape of the shoreline in the United States, diking, draining, filling, and developing our tidal wetlands,” I say to Bourgeois. “Do you ever take a step back and wonder if you aren’t doing the same thing—I mean, to make a horizontal levee or one of those islands, you do have to dump dirt into the bay—with a different set of information?”

Bourgeois laughs and says, “Huh,” as if he is surprised. Then he asks me to clarify the question. But before I get the chance he speaks.

“If you want to talk about landscape-scale change, all you have to do is look to Louisiana. The whole southern edge of the state is melting away, gone,” he says. “We’re trying to restore natural processes so these wetlands might escape that fate. Is it risky? Yeah. But I think doing nothing is even more so. Since the project’s start, bird populations have more than doubled. We are making the best decisions we can with the knowledge we have. And we have a lot of knowledge. Is this perfect? No. Would I prefer to move Alviso out of the way and let the marshes migrate inland? Sure. Would that be a better solution? Absolutely. But politically it’s not feasible.”

“There are places that are retreating,” I say.

“Really?” he asks.

I tell him about the Isle de Jean Charles, a small island in southern Louisiana where HUD just awarded residents a $48 million grant to move away from flood risk together. Bourgeois listens, and for a moment his mouth goes slack. The Coast Starlight’s 12 silver cars slide through the marsh like an arrow through the sky.

“The thing is, land in the Bay Area is some of the most valuable per square foot in the country. I don’t see us giving that up anytime soon,” he finally says. It is a sentiment that will be repeated regularly by nearly everyone I meet. And it is one of the driving factors behind the Resilient by Design Challenge that the Rockefeller Foundation launched in May of 2017, a competition that Bourgeois and his compatriots are regularly asked to aid by providing consultations.

Together we pass a notch in the levee where salt water from the bay enters the ponds. From beneath the bridge’s steel grating comes the burble of tidewater in motion, and from out in the middle of the pond comes the Caspian tern’s raspy call, its insistent kowk, kowk, kowk. I can’t tell if this is an actual bird or a recording meant to trick passing migrants into staying and breeding. Either way, when I look out toward the man-made islands in the middle of the former salt ponds, I see the flutter of dozens of charcoal-tipped wings.

A few days later, I walk from the Bay Area Rapid Transit to Robin Grossinger’s house, in the borderlands between Berkeley and Oakland. On my way I pass thousands of flowering succulents: pygmy weed and aloe, jade and spurge, tremendous plate-size purple aeoniums. The rains that broke the five-year drought have coaxed nearly every plant into bloom.

Grossinger is a historical ecologist at the San Francisco Estuary Institute who uses old records—coastal survey maps, journal entries, photographs—to reconstruct an image of the bay as it once was. And like Bourgeois he too is “on call” for all things related to Resilient by Design. “My first task, back when I was a Ph.D. student, was to research historical mapping of the bay’s tidelands,” he says. “To be honest, at the time it sounded totally boring.” Soon, however, his interest grew. “In order to figure out how we get the bay of today, I needed to figure out which species and ecosystems had been able to withstand the most alterations. I started to think of it as a detective story.”

Grossinger spent years digging through piles of maps in the archives, mesmerized by their beauty and the clues they presented. Then he took copies of them out into the real world, in search of which elements persisted and which did not. “I remember when I realized that we used to have 27 miles of sandy beach in the bay. That surprised me. But even more important was the realization that if those beaches aren’t in our memories then they aren’t in our lexicon, and if they aren’t in our lexicon they also aren’t in the palettes of all those landscape architects and naturalists attempting to bring back and buffer the estuary.”

Many of the remnant marshes in the Central Bay were once fronted by a beach, and that beach protected the wetland. It slowed erosion and provided nourishing sediment, helping the marshes make it into the present tense. “We’re applying that historical insight to our interventions in the physical landscape today,” Grossinger says. “In Marin County, we’re reusing sediment dredged from the shipping channels to build up a buffering edge along some of the most rapidly eroding marshes.” Like Bourgeois’ project in the South Bay, this too is relying on recycled dirt to accentuate the marshland’s inherent adaptive capacities. “It’s really cool,” Grossinger adds with a cluck.

Resilience then might mean keeping as many options available as possible. “We’ve been defining resiliency in so many different ways for so long,” Grossinger says. “Mostly this amounts to a hodgepodge of interventions that create temperature refuges for hummingbirds and velocity refuges for salmon. Specific solutions for specific animals in specific places. But if you understand the science of how these landscapes work, then you can’t avoid thinking that bigger moves need to be made. We need to reconnect our ecosystems across landscapes. For example, we need to remove dams so that sediment trapped in reservoirs is actually coming down the streams and making it into the bay. That would increase the resilience of so many aspects of the system. It would put more silt into the water column, accelerating accretion rates that would help marshes gain ground” and keep pace, at least in the short term, with sea level rise.

What Grossinger is proposing is a shift toward a preservation strategy known as “conserving the stage.” Instead of asking which locations or ecosystems certain species need to survive, it focuses on the physical factors that foster biodiversity in the first place: soil types, hydrology, landform variation, and, above all else, topography. Classifying landscape resiliency as a function of topographical variety goes a long way toward explaining just how vulnerable tidal marshes—and the thousands of species dependent upon them—are. After all, most sit within three feet of the highest high tide. Instead of setting aside selected areas (a particular national park) or ecosystem types (wetlands refuges), Grossinger argues that we need to create arenas where evolution can continue to unfold, that we need to foster topographical diversity in landscapes that have little.

Forty years ago, when the fight for the area’s wetlands took shape, environmentalists often used the Endangered Species Act to earmark pockets of extant marshland for preservation. If they could find a single salt-marsh harvest mouse rooting around in the pickleweed, then they could make a case for saving that little postage stamp of land from development. Grossinger’s proposal takes giant steps back from this conservation strategy. “We can’t preserve the salt-marsh harvest mouse if the salt marshes themselves cease to exist,” he says. “What science shows us is that we need to be infusing our work with an understanding of Big Nature, of landscape-scale change. And that includes different kinds of actions, involving multiple agencies, agencies that really don’t have a responsibility to solve the whole problem. But if we can create partnerships across them—as we are doing here with Oro Loma, where wetlands restoration, flood resiliency, and sewage treatment are all being tackled together—then the results can be really profound.”

“Oro Loma?” I say, repeating the enchanted words that I’ve already heard from Bourgeois.

“Yeah, you have to make it out there,” Grossinger says. “Think of it like this: If we can get Oro Loma to work, we will be, for the first time in history, reconnecting a kind of freshwater creek to the bay. And when we do that, we begin to feel reconnected to the deep nature of a place. Thinking—no, living—in this way is going to be better for us overall. We are going to have healthier, happier communities.” He pauses and looks right at me. Do I buy it? Do I buy that sea-level rise might not just be a catalyst for cataclysm, but might also pave the way for a massive, ultimately beneficial cultural transformation?

Yes, I want to say, yes. But who among us will get to live in the resilient, climate-ready cities we are designing along the water’s edge? Alviso, East Palo Alto, Redwood City, and Richmond have long been relatively affordable because of their flooding problem; “conserving the stage” would remove some stressors, but introduce others. The people of the South Bay are sandwiched between rising tides on one side and Silicon Valley on the other—a position not so different from the one that most tidelands species currently occupy. A position that often leaves those species with precious few options: retreat or perish in place.

I visit Oro Loma. It is breathtakingly beautiful in its understated way. Behind the horizontal levee is a small freshwater-treatment wetland, where partly cleaned wastewater filters through cattails and bulrushes to break down contaminants and remove nutrients that cause excessive algal growth in the bay. Then it seeps into the wide levee, through willows and creeping wild rye, Baltic rush and basket sedge, western ragweed and California blackberry, all laid down in rows. These plants continue the work the treatment wetland began, sucking up the nitrates and phosphorus that remain. And yet as I look out over this wide, man-made levee, my mind is pulled in two directions at once.

Is Oro Loma too similar to the massive infrastructural missteps we have made in the past? A seemingly easy solution that might compound the problem in unforeseen ways? Or is this 500-foot-wide earthen berm ultimately trivial, even if one existed in every rehabilitated wetland from San Jose to Marin County—its meager size ill suited to the immense changes that sea-level rise has already set in motion? I circle the project two, three, four times on foot, unable to decide. Too big or too small? Too hubristic or too narrow-sighted? At least it is not another seawall or another set of stilts. At least it is attempting to mimic the natural defenses we have spent the past two centuries paving over. At least it is designed to benefit species other than ours. This counts for something.

The air is musty with the smell of sewage, and salt water laps at the concrete retaining wall separating the project from the bay. Many more tests need to be run before the sanitation department can release the treated wastewater into the largest estuary on the West Coast. For now, the system remains closed. An experiment that many hope will turn into an adaptation strategy.

On my way out of town, I stop at the San Francisco Estuary Institute to speak with Jeremy Lowe, a senior environmental scientist for the Resilient Landscapes Program that Grossinger runs, and the person behind the horizontal-levee concept. Lowe is a coastal geomorphologist who has been working in climate-change adaptation for over 30 years. He has designed floating floodgates for Venice and minimized coastal erosion at the Hong Kong airport. But for the last decade or so he has focused on nature-based sea-level-rise readiness strategies for the West Coast. Not more than five minutes into our meeting, he surprises me by saying what no one else working in wetlands restoration and resiliency will: that Oro Loma and the South Bay Salt Pond Restoration Project and the innovative uses of dredged materials aren’t solutions in and of themselves. That they aren’t going to reverse the tide and they aren’t going to solve the problem of equity. That there is no silver bullet.

We are sitting together, looking at a map of the bay that Lowe’s institute recently published. It inventories all the different kinds of resiliency projects taking place, from wetlands restoration to horizontal levees and beach replenishment. “What we’re doing is buying time, some buffer, in which to wrap our heads around the fact that—in the grand scheme of things—this isn’t going to work,” Lowe says. “We’re going to have to move infrastructure; we’re going to have to move people. Lots of them. And in the meantime, if we can make our marshes more resilient to buy us all—humans, plants, and animals—some breathing room in which to figure out how to retreat responsibly, then let’s do that.”

We talk for a while longer, then I walk out of his office, down the spiral staircase to the lobby, and outside. The early-evening breeze turns the leaves of the cottonwood. Costco is to my right, Ice Chamber Athletic Performance Training to my left. In front of me, a snowy egret stands knee-deep in the bay. Lowe’s words ring in my ears: “This isn’t going to work.” None of it: not the horizontal levees or the sediment slurries, not the seawalls or the living dunes, not the raising of homes and streets or the pumping out of salt water, not flood-insurance reform or visions of a 22nd-century Venice. The water will come, and at some point, we are going to have to admit a kind of defeat. An acceptance of the idea that nothing important is ever easy or quick. And that real resiliency may mean letting go of our image of the coastline, learning to eventually leave the very places we have long considered necessary to our survival, and helping the most vulnerable amongst us––human and more-than-human––move inland, too.

This post is adapted from Rush’s upcoming book, Rising: Dispatches From the New American Shore.