Bay Area Communities Unite to Take On Sea Level Rise

Jennifer Adams stared out over the low-lying shoreline of East Palo Alto, California. Gulls twisted and dove over the bay while great blue herons and snowy egrets prowled the muddy tidal channels. Adams is the environmental-justice program director at the nonprofit Nuestra Casa. We met here, at the revived wetlands of Cooley Landing Park, to discuss East Palo Alto’s long-running blight—and how sea level rise threatens to exacerbate it.

The city, about 30 minutes south of downtown San Francisco, inhabits a flood-prone, industrialized parcel of land surrounded by some of the wealthiest communities and corporations in the United States. Palo Alto proper, its more affluent neighbor, occupies slightly higher ground leading up to the foothills of the Santa Cruz Mountains. To the north, along an adjacent parcel of shoreline in Menlo Park, squats the Facebook/Meta campus. To the south, in Mountain View, is the so-called Googleplex, the global headquarters of Google and its parent company, Alphabet.

In the mid-19th century, East Palo Alto, then known as Ravenswood, was a center of shipping and brickmaking. In the 20th century, more heavy industry, including a steel factory and petrochemical plants, crowded in along the shoreline. Before becoming a park in 2012, Cooley Landing was a municipal dump. East Palo Alto’s most troublesome site lies at the western margin of the marsh—a former hazardous-waste processing facility, which between 1964 and 2007 left heavy metals, dioxins, and polychlorinated biphenyls (PCBs) in the ground.

Jennifer Chang Hetterly (left) and Jennifer Adams work to restore the Bay Area shoreline.

Adams explained that rising ocean levels could raise the groundwater table, mobilizing the toxins in the soil across the city. “Our community is right on the bay, and there is very little buffer between the sea and the homes,” she said.

That buffer is an approximately 300-yard-wide section of tidal marsh, restored from the dump site in the early 2000s. At the western edge of the wetland, near the houses, stands a levee. This small barrier—no more than three or four feet higher than the bay—will soon be no match for rising waters.

Few places illustrate the complexities of preparing for sea level rise more than East Palo Alto. But the Bay Area’s challenges are not limited to this corner. Addressing them will require a large-scale and coordinated response—one that restores ecosystems that have been systematically impacted by industry for years while meeting the needs of individual communities.

In that effort, environmentalists and engineers are using a diverse set of tools, including nature-based solutions, to remake the spongy wetlands that once existed along the fringes of San Francisco Bay as bulwarks against rising seas.

Prior to the 1850s, the Bay Area had an estimated 540,000 acres of tidal wetlands and marshes at its edges. As the region was settled, those wetlands were dredged and filled. The squelchy zones were considered swamps, breeding grounds for mosquitoes, and places of filth and pestilence.

It is hardly an understatement to say that the Bay Area’s tidal marshes were trashed. Over time, they were filled in with construction debris, mud dredged from the bay, and even household waste. Today, the Mission Bay neighborhood south of downtown San Francisco is a modern cityscape. But it was once known as “Dumpville” because it hosted the city’s largest landfill, which occupied the marshes around Mission Creek. In 1895, the San Francisco Chronicle described a “thick, slimy mass” of garbage “moving lava-like” into Mission Creek and the bay.

More than half of present-day San Francisco now sits on filled-in tidal marshes. As in other coastal cities across the nation, San Francisco’s marshes were paved over to expand the city’s footprint. Critical pieces of infrastructure—highways, water-treatment facilities, power plants—as well as entire communities were subsequently built atop the former wetlands.

Across the bay, much of downtown Oakland, along with its massive port, also occupies what was once a vast estuary with a network of spongy wetlands and meandering tidal channels. Huge sections of the South Bay, including San Jose, Sunnyvale, Foster City, Menlo Park, and Mountain View, likewise stand on former tidal marshes.

An ecological reckoning came in the early 1960s with the Save the Bay campaign, founded by three Berkeley citizen activists, as the US Army Corps of Engineers was looking to fill huge sections of the bay for urban development. Awareness of the importance of the bay and its ecological functions grew, and in 2008, California passed the San Francisco Bay Restoration Authority Act, which required large-scale protection and restoration of tidal wetlands.

That grassroots bay activism lives on through the Sierra Club’s Bay Alive Campaign. Launched in 2021 with a generous bequest from a longtime member, the campaign is a partnership between the Loma Prieta, Redwood, and San Francisco Bay Chapters. Its primary objective is to build community resilience to sea level rise by protecting and enhancing shoreline ecosystems.

“We decided that sea level rise was the single biggest threat facing the bay and that regionally coordinated adaptation planning was a critical first step towards resilience.”

“We did all sorts of research about the best way to make a lasting impact,” said Jennifer Chang Hetterly, coordinator of the Bay Alive Campaign and a Loma Prieta Chapter member. “We decided that sea level rise was the single biggest threat facing the bay and that regionally coordinated adaptation planning was a critical first step towards resilience.”

A major legislative victory came in 2023 with the passage of SB 272, a landmark bill requiring communities to prepare for sea level rise through programs such as regional shoreline adaptation plans, or RSAPs. The Bay Alive Campaign and its supporters played a key role in shaping SB 272, helping ensure that the final version included both environmental protections and environmental-justice provisions.

Hetterly and her Sierra Club colleagues worked closely with the San Francisco Bay Conservation and Development Commission, the agency overseeing SB 272’s regional shoreline plans. Together, they developed guidelines ensuring that natural solutions would be prioritized and that disadvantaged frontline communities like East Palo Alto, Richmond, Vallejo, and San Francisco’s Bayview and Hunters Point neighborhoods were included in the decisions.

“Industrial legacy contamination, flooding, displacement—all these things come together and pile on these communities,” she told me. “We wanted to make sure those communities were part of the conversation and that their voices were reflected in the solutions.”

Even in their highly urbanized and altered state, San Francisco Bay’s wetlands are of vital ecological importance.

“Seventy-five to 85 percent of the state’s tidal marshes are in San Francisco Bay,” said Arthur Feinstein, regional chair of the Bay Alive Campaign and former director of the Sierra Club’s San Francisco Bay Chapter, who has been involved in the protection of California wetlands for over four decades. “It’s mind-boggling.”

Shorebirds thrive in this marginal zone between land and sea. Juvenile salmon find shelter in the shallow waters and aquatic grasses. Healthy wetlands also mitigate storm surges, sop up toxins, and sequester carbon.

Tidal marshes are key for not only critters but also the state’s economy. According to the National Oceanic and Atmospheric Administration, approximately 70 percent of US commercial fisheries rely on the shallow water habitats afforded by marshes and eelgrass beds (another of the bay’s imperiled ecosystems). “If you lose [the marshes], you lose a whole lot of fisheries that we depend on and a whole lot of other fish that also depend on them,” Feinstein said.

Around the bay, nature-based solutions are being used to provide flood control while also remaking habitat across tens of thousands of acres of marshland. Rather than using only concrete seawalls and riprap breakwaters, engineers are devising structures called ecotones and horizontal levees, gently sloping shoreline modifications that more closely mimic tidal zones. One can get a glimpse of these earthworks at the massive South Bay Salt Pond Restoration Project, a collaboration among dozens of organizations including the California State Coastal Conservancy, the California Department of Fish and Wildlife, the US Fish and Wildlife Service, and the Santa Clara Valley Water District.

A focal point of the restoration project is Alviso, a small community of about 2,000 people on the outskirts of San Jose that sits 10 to 15 feet below sea level. Once surrounded by miles of orchards and filled with bustling canneries, Alviso has been hollowed out by floods. The largest was in 1983, when water displaced hundreds of people. When complete, the Alviso segment of the project will include several miles of earthen levees along with 2,900 acres of rejuvenated wetlands remade on horizontal levees.

The urgency is real: In a worst-case scenario, sea levels around the Bay Area could rise by six to nine feet by the end of the century. At that point, said Feinstein, “Interstate 80 is underwater; [Highway] 101 is underwater. Many of our communities would be underwater.”

Rebuilding and restoring tidal marshes will be critical in the effort to protect infrastructure from rising waters. That’s where East Palo Alto and its restored marshlands around Cooley Landing Park come in.

Adams said that after decades of neglect, the local community finally has a say in reshaping its shoreline as climate change and rising sea levels bear down.

“It’s easy to say, ‘Let’s just do managed retreat,’” said Adams, looking out over the windswept waters of the bay. “That’s going to be the easiest way to solve this issue, right? It gives us a bigger buffer between residents and the ocean. But for a lot of residents that we talked to, that’s not an option. If they leave East Palo Alto, they get displaced in the Bay Area, and this is their home.”

Adams and advocates in the Bay Alive Campaign are determined not to let that happen.

“We are all in that fight together,” she said.