Fighting sea level rise together

“Unfortunately this county of San Mateo is projected to be one of the most impacted in the state when it comes to sea level rise due to climate change,” Mullin said, noting that sea level rise is already causing erosion on the coastside of the county while the eastside of Highway 101 and SFO are at risk of being inundated by flooding. “The property losses, economic losses and the loss of basic services such as power and the sewer system are real impacts of sea level rise that we must plan for.”

Mullin added, according to U.S. Geological Survey and the Pacific Institute, $100 billion of the $150 billion of shoreline economic assets at risk in California are in the Bay Area, with San Mateo County’s risk estimated at $24 billion.

There’s scientific consensus that sea level rise will be between half a foot and a foot within the next decade, and up to 7 feet or higher by the end of the century, said Rachel Ehlers, principal fiscal and policy analyst in the Legislative Analyst’s Office.

“And it’s not just the rising seas but also the impacts of storms and king tides that will bring that water up, maybe more episodically, but there are still structures there that are going to flood,” she said.

Larry Goldzband, executive director of the Bay Conservation and Development Commission, said models show just 2 feet of flooding around the Bay will make homeless between 60,000 and 90,000 people, many of whom are underserved and likely won’t be able to return to the area.

Groundwater in the Bay Area is also a significant and lesser-known component of sea level rise, said Kristina Hill, associate professor of landscape architecture, environmental planning and urban design at the University of California, Berkeley.

“I’m talking about the kind of groundwater we have too much of, not the kind we have too little of,”ˇ she said. “I’m talking about unconfined water that just sits in the pore spaces of the soil and near the shoreline that’s very shallow. It’s dirty, it’s not a drinking water resource really.”

Hill said she and her colleagues have discovered an “enormous area” of the Bay edge is already within 3 feet within the water table. She said 1 meter of sea level rise could flood about 28 square miles of land without new levees or walls, while an additional 40 square miles could be flooded by groundwater.

“Even if we build new walls and levees with assistance from the state, I hope, we could still see flooding on the inland side of all those levees because the groundwater would equalize with the sea level,” she said. “We could spend hundreds of billions of dollars and still have flooding on the inside of those levees.”

Hill went on to list the myriad impacts of groundwater, noting that most maps outlining flood risks due to sea level rise don’t account for groundwater.

“Groundwater can cause infiltration of storm and sewer pipes and cause them not to function, it can cause foundations and underground structures to heave, increase the risk of soil liquefaction, a very important issue for all of us, removal of soil contaminants and last, emerge to the surface as ponded water for increased creek flooding,” she said.

Hill said one potential solution is the Bay Area could build its way into adapting to a high water table like the Netherlands, which built artificial ponds and then put luxury housing on those ponds.

“That’s the ultimate monitoring device there. People are living in the infrastructure and they’re watching how it’s all changing and they’ve taken some housing pressure off of other areas,” she said.

Amsterdam has built three-story pre-fabricated floating homes that are flexible and easy to move, while Germany built finger wharves that allow flooding to occur on the outside of the wharves while people can still get around on the inside of them and don’t have to evacuate, she said.

“They have a second story circulation system and waterproof parking garages,” she said. “We can do that.”

But most of the recommendations offered during the meeting related to regional collaboration and, of course, funding. A $5 billion climate resilience bond is already in the works and will likely go before voters in November.

Officials from Foster City and Redwood City spoke during the meeting about the threats they’re facing in their cities due to sea level rise and the ongoing efforts, including the raising of levees, being implemented in response. There were also presentations on major sea level rise resiliency projects underway at the Oakland and San Francisco airports.

Officials stressed many more projects are needed to sufficiently protect coastal communities and that various steps must be taken before they can break ground. Ehlers, among others, recommended investing in planning and setting up regional partnerships before launching major projects.

“We need to start doing some projects, and pilot projects in particular, to learn, but we don’t want to infuse so much funding immediately if good projects aren’t ready to go and the planning isn’t in place,” she said. “We need to be strategic and have a coordinated approach and we can’t do that without having the partnerships set up to think about things on a regional basis.”

Warner Chabot, executive director of the San Francisco Estuary Institute, echoed the need for enhanced collaboration and said a roadmap has already been outlined in a seal level rise report published by the Legislative Analyst’s Office. But funding is needed to make it a reality.

“The Bay Area has demonstrated effective collaborations that work across jurisdictions. We just need state support to enhance local capacity,” he said.