For This Bay Area Island City, Water Is Coming From All Sides

Danielle Mieler spread out maps of Alameda across a concrete table at a park on a bluff overlooking the city of nearly 80,000. A ferry from San Francisco approached the island’s sandy western shore.

Each map highlighted a different flood risk — one showed low-lying areas in blue and green, another projected sea level rise in blocks of purple. In one of the more ominous maps, Alameda appeared in red, indicating areas where saturated soil could liquify during an earthquake.

Mieler, the city’s sustainability and resilience manager, pointed to a grey stretch of land in the city’s center — the only area her team does not expect to plan protections from future flooding, she said. Still, because Alameda is an island, flooding will affect all residents.

“It’s kind of a lot when we think about all that needs to be done, and we’ve started to wrap our heads around that,” Mieler said. “We need to raise the shoreline.”

The city tasked Mieler and her team with completing an adaptation plan for Alameda, including solutions, by early 2028. They are considering lining beaches with boulders to slow waves, raising earthen and concrete barriers to keep water from entering neighborhoods and even letting the bay reclaim parts of the island. They’re also planning nature-based solutions, such as restoring marshes and experimenting with oyster reefs.

“It’s like a little testbed,” for potential fixes that cities around the Bay Area could use, Mieler said.

The Bay Area’s most populous island isn’t trying to adapt on its own. Alameda is among the first to align with a state-led sea-level rise plan, mandating that every coastal city and county in the Bay Area develop plans to address sea level rise. The city is collaborating with Oakland and the Port of Oakland on a plan to protect the area.

Alameda is a strong case study for the Bay Area, climate scientists said, because it will need to use every tool possible to protect its 360-degree waterfront. But they caution city planners against overhardening shorelines and encourage them to embrace living with water where possible.

“Alameda feels different because it’s surrounded, but if you unspool it and make it linear, it’s the same challenge that’s faced by any other bayfront community,” said Mark Stacey, a UC Berkeley professor of civil and environmental engineering.

‘It’s all a little bit man-made’

Alameda wasn’t always an island, and its non-island portion, called Bay Farm Island, ironically, was once only an island at high tide. In 1902, the U.S. Army Corps of Engineers finished dredging a canal between Alameda and Oakland. Later in the century, developers filled in the marshy peninsula connecting the Bay Farm area to the shore.

“It’s all a bit man-made,” Mieler said. “We like to think that this is what Alameda is, but this is not what Alameda was 100 years ago, and it’s not what it’s going to be in 100 years either.”

The island is relatively flat, with its highest elevation just 39 feet above sea level. In addition, much of the island was built on fill.

“Alameda is at the forefront of sea level rise hazards,” said Kevin Befus, associate professor at the University of Arkansas Department of Geosciences. “If we left things as is and sea levels were higher, large areas of the island would flood.”

California has experienced about 8 inches of sea level rise over the past century. As the world continues to warm due to fossil fuel burning, the bay could rise about a foot by midcentury and more than 6 feet by the end of the century, according to the state’s latest sea level rise guidance.

Alameda can expect water from all directions: rising seas, torrential downpours, storm-driven surges that intensify high tides and groundwater pushed upwards as soils become saturated.

People living on this 23-square-mile island got a preview of that wetter future in January during abnormally high king tides. Waves crashed into dunes, filling Shore Line Drive. Runners splashed through brackish water pouring onto trails, and water gushed from at least one storm drain.

The flooding mirrors what daily tides will look like by midcentury, and Mieler said, the spots that “flooded were places that we know need to be addressed.”

If the city took a do-nothing approach, Mieler said, water could engulf streets, homes, businesses, and the Posey and Webster Street tubes that connect traffic to Oakland and the mainland.

But water from above is not the only issue. Patrick Barnard, research director for the UC Santa Cruz Center for Coastal Climate Resilience, said about 60% of Alameda’s groundwater is already close to the surface — without further sea level rise.

“We know there are lots of issues in Alameda, but bottom line, it’s effectively ground zero for groundwater hazards in the Bay,” Barnard said.

Kris May, who has lived in Alameda since 2011, knows this firsthand. She’s already dealing with rising groundwater in her home, where water pushes through cracks in her basement floor. She installed two sump pumps to remove it.

“Our sump pumps work great, but the water keeps finding new ways to get in,” May said.

May is one of the scientists the city has hired to understand flood risk and develop solutions. She’s the founder of Pathways Climate Institute, a San Francisco-based consulting firm, and has conducted extensive research on groundwater rise.

“Sea level rise is pushing that baseline groundwater table up and reducing that kind of sponge capacity,” May said. “It’s a hazard that is getting worse and worse over time.”

‘That’s one of my nightmares’

To protect this island from the nastiest effects of the altered climate, the community will need to decide what it values enough to save.

“What is that thing that gives that sense of place, and how can that be saved?” Stacey said.

One of those places could be Alameda Beach on the city’s west side, where hundreds gather on hot days. Stacey said that if the city decides the beach is worth preserving, planners could study how to retain sand during storms and develop other solutions. But he noted the beach is human-made, and that preservation may require “some retreat” so it can migrate.

For Alameda residents like Alex Spehr, protecting outdoor spaces is important. “I like our beaches,” Spehr said, but acknowledged that if “our beaches all wash away, at some point, you can’t just keep dumping sand to replace them. Preserving our habitat is important.”

On the city’s east side, along a channel facing Oakland, seawalls and levees may be the best option. Fixes will require cooperation from businesses and private property owners. The traffic tunnels onto the island are also at risk of flooding, and May said a sea wall and levee will likely protect them.

“You would not want to be driving through that tube during a flood when water can come in,” May said. “That’s one of my nightmares.”

Planners want to restore wetlands around the island and enhance eelgrass beds. They have also proposed boosting oyster habitat by constructing reefs made from discarded restaurant shells, which chickens clean, cured in the sun and then dropped into the bay to attract larvae.

“Wild oysters smell that calcium from miles away, and they come running,” said Jonathan DeLong, executive director of Alameda’s REAP Climate Center.

But the biggest hurdle ahead for the island city is securing funding to pay for fixes, especially since federal dollars for climate-related projects are scarce.

“It’s gonna be a big dollar amount,” Mieler said, noting that protecting the island will likely cost billions.

Mieler said she remains hopeful.

“This is a multi-generational problem,” she said. “We’re trying to start early so that we can be thoughtful in our planning and leave the space for future generations to come make their own decisions about what solutions look like and to respond to conditions as they unfold.”