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A City Rose on the Marshes. Will the Bay Take it Back?

One of the newest communities on San Francisco Bay is preparing for the water around it to rise as the world warms. But what preparation is enough? And for whom?

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Water World The lagoons and civic center of Foster City seen from the air in 2007. Ken Sheppardson via Flickr
 

By Rebecca Nelson

An eight-mile long levee 13 feet high stands between homes in Foster City and San Francisco Bay. Bob Cushman has lived there for twenty years, a little less than half the time the city has existed. In the 1960s, Foster City was created on the wetlands just south of the San Mateo bridge. This planned community, which now has a population of nearly 35,000, became incorporated in 1971. Cushman’s home on Greenwich Lane is close to one of the city’s many lagoons.

The melting of distant glaciers caused by climate change could well have a serious impact on Foster City as sea levels rise. Flood maps produced by Our Coast Our Future, a collaborative group that uses information from the U.S. Geological Survey, show that rising water could eventually inundate most of Foster City. But how soon? And what can be done?

Flood maps show that without improvements to the levee, rising waters could inundate most of Foster City.

Potential for Big Flood Insurance Bills Got Residents’ Attention

The Federal Emergency Management Agency changed its flood maps in 2014, Foster City’s public works director, Norm Dorais, said in a recent interview. The changes required an increase in the height of the 13-foot riprap levee, an embankment built around loose stone or concrete fragments. Unless this was done, FEMA would place Foster City in a flood zone, mandating that all homeowners at risk would have to take out expensive flood insurance.

Had that happened, Dorais said, the average homeowner with a federally insured loan would have to pay a minimum of $2,000 to $3,000 annually for flood insurance. More than 80 percent of the city’s residents voted last summer for a $90 million bond to raise the levee by eight feet.

Vulnerabilities Found in its Armor, Foster City Girds for Rising Seas

Foster City rose in the 1960s on a marshy island that had earlier been reclaimed from San Francisco Bay. To the developer, T. Jack Foster Jr., proximity to water was central to its marketing allure, as neighborhoods rose with names like “Dolphin Bay,” “Treasure Isle,” and “Sea Colony,” among others, and the island was laced with canals for dockside access.

To hold the tides back, the island is fringed with defenses, from 13 foot high levees on the bay side, to hardened embankments along the canals. The Federal Emergency Management Administration, FEMA, recently found those defenses wanting, ordering Foster City to bolster them or face designation as a flood-prone area – an expensive proposition for homeowners.

Relief map showing Foster City and bay shoreline of San Mateo County

Sources: Adapting to Rising Tides program, San Francisco Bay Conservation and Development Commission; San Mateo County; San Francisco Estuary Institute; Natural Earth Data; ESRI Earth Imagery; NASA Elevation Data

Geoff McGhee/Bill Lane Center for the American West

“I think the levee was needed,” Cushman said, “We do believe that sea rise is a problem.” The city will use property taxes to pay off the bond over 30 years. According to the city, this will cost homeowners approximately $40 a year per $100,000 of assessed property value. “We’re trying to be proactive,” Dorais said.

Raising Levees Postpones Disaster

The levee is currently 13 feet above sea level, and Foster City plans to raise its height by eight feet in order to meet both FEMA’s flood requirements and the San Francisco Bay Conservation and Development Commission’s even more stringent requirements.

Our Coast Our Future summarizes predictions from a variety of climate models, showing that 2050 sea level rise projections range up to two feet and 2100 projections anticipate increases up to almost nine and a half feet. Foster City used San Francisco’s more modest 2014 sea level rise guidance for their projections of one and a quarter feet of sea level rise by 2050, and a little under four feet of rise by 2100.

Current Levees Could Fail When the Water Rises 4.3 Feet

Whether borne by flood, sea level rise, or some combination of the two, models show that Foster City’s current storm protection should keep it dry until the water level rises 52 inches above the current mean water line. Future danger could come from calm waters under a climate change scenario where sea levels rise four feet. It could also come from a 100-year storm surge rising from seas just one foot higher than they are today.

Predictions like these, coupled with FEMA’s decision to designate much of Foster City a flood-prone area if its levee were not raised, prodded city residents to support a bond to raise the levees as much as eight feet.

The Levee Will Eventually Protect a City Below Sea Level

While Foster City is nominally at sea level under current conditions, analysts point out that even just one foot of sea level rise would leave much of the city below sea level. In such a scenario, the levee would operate as a dyke, and any potential leaks could risk causing a flood.

Bay Shoreline Flood Explorer – Click to Open in New Window

Sources: Adapting to Rising Tides program, San Francisco Bay Conservation and Development Commission; San Francisco Estuary Institute;

Foster City’s watery heritage is its pride. In his 2012 memoir, T. Jack Foster Jr., one of the city’s founders, wrote, “One of our goals for Foster City was to create a ‘sense of place.’ This is a feeling that, wherever you in Foster City, you know you are in Foster City.” He had hoped that the city’s lagoons would contribute to this sense of place. Scenic trails lead along the lagoons, the levee and through protected marshes, providing an idyllic space for birdwatching, biking, and hiking.

Scenic trails lead along the lagoons, the levee and through protected marshes, providing an idyllic space for birdwatching, biking, and hiking.

Several residents at a local Starbucks described Foster City as culturally diverse. About 45 percent of the population identifies as Asian. Families comprise about 70 percent of households. The population grew from around 9,000 in 1970 to nearly four times that number today, federal census data shows. This data puts the median household income at $129,000, well above the median in the surrounding San Mateo County.

“How concerned am I about climate change as it affects Foster City?…Practically not at all,” said Bob Berger, who has lived there for about five years. Although Berger thought that “the levee spend may be warranted,” he criticized, “the vote on the levee improvements, in my opinion was a combination of fear mongering and insurance blackmail with few real facts to support it.”

In a KQED report last June, T. Jack Foster Jr. agreed with Berger. Foster opposed the levee improvements, saying he wouldn’t have done anything different in developing Foster City and that the seas were not rising quickly.

Pleasure Island Windsurfers competed in the lagoon off of Foster City’s Leo J. Ryan Park in the summer of 2010. Sreekanth Jandhyala via Flickr
 

In 1958, a Developer’s Vision Turned a Marshy Island into a City

As Foster wrote in his memoir, a farmer named Frank Brewer built the levee in 1900 to create a meadow for grazing cattle and cultivating hay. The Fosters, an Oklahoma real estate family, bought Brewer Island in 1958 to create their planned community. Around the island they deposited 18 million cubic yards of compacted sand, despite the Sierra Club’s opposition. Foster’s confidence in his company’s creation has persisted from the time of the city’s original construction though today. He was proud that the 1989 earthquake left the city largely unscathed.

The levee has been adjusted over time to prevent the bay from reclaiming the town. Discussions of the city’s future are intertwined with that of the levee.

“Foster City all used to be tidal wetlands a hundred years ago,” explained Christina Toms, a senior environmental specialist at the San Francisco Bay Regional Water Quality Control Board. The levee has been adjusted over time to prevent the bay from reclaiming the town. Discussions of the city’s future are intertwined with that of the levee.

With a Higher Levee Three Years Away, Will It Be Effective for the Decades to Come?

The levee as it appears now, south of the San Mateo Bridge.

The levee as it appears now, south of the San Mateo Bridge.   Rebecca Nelson
 

According to Dorais, the public works director, Foster City plans to start the levee improvements in summer of 2019 and hopes to finish by December 2021. Dorais thinks “We will meet 2100 numbers [for sea level rise] from a still water point of view, but it’s the wave run-up…that we would need to deal with.” He hopes that by 2050, technological innovations will offer more advanced protections.

Foster City will raise its levee using sheet pile walls, a type of retaining wall that is commonly used for flood protection. Christina Toms explained that the geophysical properties of bay mud mean “There’s a physical limit to how tall the sheet walls can be.” She added that the city engineers determined that increasing the levee’s height with sheet piles will only provide protection against the sea level rise of one and a quarter feet projected by 2050. She said it won’t stave off the water if it rises almost four feet by 2100. As a possible solution, Toms advised Foster City to enhance beaches to improve flood protection.

Renderings of the Foster City shoreline before and after levee raising.

Renderings of how a raised levee would appear at ground level, distributed in 2016 as part of the city’s pitch for the improvement project. The “2050” scenario reflects the eight-foot height increase that is currently underway. There are no current plans to raise it to the “2100” height.   Schaaf & Wheeler, with assistance from BFS Landscape Architects
 

Levee or No, Floodwater Can Also Come from Inland, Underground… Or Nearby Towns

The levee expansion is designed to cope with rising waters on the city’s bay front. But experts question how well it will deal with all the consequences of rising seas. Sloughs border Foster City’s inland side near Highway 101. Cushman, the Foster City resident, remarked, “Our potential threat from flooding is probably biggest from the 101 side. That would be a bigger threat than water overtopping the levee.” But Dorais is not worried. “As the rises come in the next twenty to forty years, those marsh areas will continue to grow and keep up.”

Expanding the levee does not deal with another danger: increasing groundwater heights. “This wall is not going to solve the issue of the groundwater,” said Rohin Saleh, the Alameda County Flood Control watershed planning manager. Saleh’s colleague, Hank Ackerman, Alameda Flood Control’s principal civil engineer, added, “You could have utilities, foundations to buildings, that become vulnerable because of the groundwater saturation. It is a very complex problem. I think Foster City jumped the gun.”

Morning light over downtown Foster City.

Morning light over downtown Foster City. Solyanka via Flickr
 

And these engineers and other experts made the point that, when it comes to rising water, Foster City is not alone. The bay’s hydrology crosses jurisdictional boundaries. A solution that works for one city may hurt another, underscoring the need for coordinated planning.

“Collaboration is really important,” said Ian Avery Bick, a Stanford researcher who is developing a risk analysis tool to help stakeholders plan for rising seas. But Bick and other experts anticipate roadblocks. “There seems to be more animosity than collaboration across the counties and the cities,” Bick reflected, “…the first quarter, we didn’t even include Foster City in our analysis because we were worried about the political consequences…”

Max Evans, a Stanford Civil and Environmental Engineering graduate student, added, “When Foster City built up the levee…where does the water go? It potentially affects other communities more.” Evans noted that Foster City’s neighbor Redwood City is vulnerable to rising seas.

Will a Bigger Levee Hurt Foster City’s Neighbors?

“When Foster City built up the levee…where does the water go? It potentially affects other communities more.”

The engineers, Ackerman and Saleh, are also concerned about how the levee may affect other towns. Following an interview, Saleh expanded his thoughts in an e-mail: “By building a flood wall around Foster City, they are also going to roughly push around 20,000 acre-feet of water during a one-hundred-year event to somewhere else in the Bay…Part of this water may be pushed toward our direction and some may go south.

“The bottom line is nobody agreed to this,” Saleh continued. “And whether it was okay with us to receive any amount of flood water from another city.” Ackerman added, “…that water’s got to go somewhere…it will impact everyone else.” But in Foster City, Norm Dorais asserted, “We understand that there are some concerns about displacement. But based on how our design is, we don’t feel that we would be contributing to any additional rise anywhere else.”

Foster City can afford expensive projects. Not every jurisdiction can. As Ackerman said, “Sea level rise endangers poorer communities that can’t afford walls.” Christina Toms agreed. “Environmental justice isn’t always part of the sea level rise and adaptation dialogue, but it really should be.” “Anyone who’s building levees right now… is possibly wasting their money,” said Ackerman, “We need to spend more time and effort looking at this as a holistic problem.”

But waiting for cooperation can waste valuable time. “Climate change is not going to wait for a permit,” said Len Materman, the Executive Director of the San Francisquito Creek Joint Powers Authority (SFCJPA). This multi-jurisdictional agency unifies two counties and three cities, encompassing the San Francisquito Creek’s watershed. It is nearing completion of a major flood-control construction project to contain the creek and the ocean.

“Don’t wait for the perfect solution, and don’t assume the federal government is going to solve the problem…” Materman advised. His agency’s successes, he said, show that planning as a watershed enables neighboring municipalities to collaborate. “It [the creek] is really what we have in common between these three cities,” he added. “They all touch it, they all depend on it, and they all suffer from it.”

That said, “unless you have a lead agency that is going to manage the project, it is very difficult to coordinate between jurisdictions,” he concluded.

Averting a “Slow-Moving Catastrophe”

San Mateo County is in the process of creating an agency to address regional sea level rise. At its November 30th meeting, the San Mateo Countywide Water Coordination Committee met to discuss how to establish it. This makes Alice Kaufman, the legislative advocacy director for the Committee for Green Foothills, optimistic. “We do hope that we can…come together and decide on a path forward on how to deal with the issue of sea-level rise” she said. “This is a problem that is sort of a slow-moving catastrophe.”

Foster City’s public works director, Dorais, believes the city’s levee project could provide an example for neighboring cities. “Overall, our experiences might help folks out…If the regional effort is for meeting 2100 sea level rise, then we will certainly contribute,” Dorais said, “But if it’s only to meet 2050, we will not contribute any financial aid…It would not make sense for us to contribute on a regional level for something we’re already doing.”

Condominiums under construction in the fall of 2018.

Condominiums under construction in the fall of 2018. Rebecca Nelson
 

As the seas slowly rise, Foster City continues to develop. Its population grew by at least 3,800 people in the last seven years, and new condominiums are under construction right now, across from the town library.

On Foster City’s bay front, families often walk along the levee with their children. “I really like living in Foster City, as I think everyone who does live here feels pretty much the same way,” said Bob Berger. He added windsurfing and boating are part of the city’s culture. The homes evoke a sense of permanence, making it hard to imagine that once there was only marsh here.

Someday, the water could return. “Projections for sea level rise have doubled to nine feet by the end of the century,” Ackerman warned, “Nobody can build their way out of that.” 

 

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Name withheld Foster City

Responding to A City Rose on the Marshes. Will the Bay Take it Back?

The cities located along the shores of the Delta, and the North Bay, the Central Bay, and the South Bay share one thing in common: A sea level rise will effect them all. If Foster City’s levee system is inadequate for sea level rise predictions, then it begs the question which other city along the shores of SF Bay estuary is adequately prepared?

8/25/2020, 12:15pm

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