Sea level rise could threaten residents, but Bay Area has no comprehensive protection strategy
Julia Scott
San Jose Mercury News
06/14/2010
Within two decades, developers could be enthusiastically selling stunning views, bay breezes — and up to 56,000 new homes — along the edge of San Francisco Bay. One thing their brochures won't mention: rising sea levels that could transform today's bay front into a perpetual flood zone.
Only half of the Bay Area's 12 proposed major bay-front developments have a strategy for the expected rise in sea level that experts warn could endanger hundreds of thousands of residents and cause some $56.5 billion in property damage in San Mateo, Alameda and Santa Clara counties by the end of the century.
With 2 million new residents projected to move to the Bay Area in the next 25 years, the issue of rising sea levels has added a new layer to a fierce regional debate over whether it is appropriate to build along the bay — or whether we should retreat from the water altogether.
"I think that, right now, Redwood City is like the canary in the coal mine," said state Sen. Loni Hancock, D-Berkeley, who recently joined more than 125 current and former elected officials to lobby against a proposal to build thousands of homes and more than a million square feet of office space on Redwood City's Bayside salt ponds.
Even though they are hungry for housing, cash-strapped bay-front cities are not inclined to spend millions of dollars on solutions to prevent future flooding. And no agency has the authority to require that cities take sea-level rise into account when planning a development.
So decisions over whether to build levees and how high to build them usually fall to a developer, said Will Travis, executive director of the Bay Conservation and Development Commission.
A few developers are taking up the challenge, but with wildly different solutions. While one developer proposes literally raising Treasure Island to keep future neighborhoods there high and dry, developers of Redwood City's Saltworks property plan to build up earthen levees to protect thousands of people from flooding.
Others — like San Francisco's Mission Bay project, which will boast more than 6,000 housing units when complete — have no flood-protection strategy at all.
'Wait and see' wins out
A growing chorus of regulators, legislators and environmental groups say the lust for prime real estate and a wait-and-see approach to sea level rise have taken precedence over cool-headed analysis of the pros and cons of building along the bay shore. They warn that the Bay Area needs a comprehensive strategy.
"For me, the major concerns are sea-level rise," Hancock said, "and what is the public liability if we allow and permit development that will be affected."
Scientists say global warming will melt glaciers and ice sheets in the coming decades, and combined with the fact that ocean water expands as it warms, the result will be a steady rise in sea levels. Since 1900, San Francisco Bay has risen 8 inches. California's Climate Change Research Center predicts that sea-level rise in the bay could reach 16 inches by midcentury and 55 inches by century's end.
Only two areas — Foster City and Hamilton Field in Novato — have Federal Emergency Management Agency-certified levees high enough to protect them from a 100-year flood event, defined as a 1 percent chance that each year will present a "perfect storm" of rains, wind and high tides.
The Pacific Institute estimates that it would cost San Mateo, Alameda and Santa Clara counties more than $2 billion to build and raise all the levees and sea walls to guard against flooding associated with maximum sea-level rise scenarios, but if measures are not taken, flooding could cause $56.5 billion in property damage by 2100.
Many of the planned developments lie partially or entirely within existing flood zones, as defined by FEMA — such as the Redwood City Saltworks site and others in Oakley and Alameda.
Parts of the Saltworks site are below sea level, but developer DMB has argued that building homes close to jobs in Silicon Valley is a benefit to the environment, preventing long commutes.
Lennar, lead builder of future communities on Treasure Island and Hunters Point, has decided to raise the land elevation and the building pads in both locations to a minimum elevation of 36 inches above the 100-year tide, rather than build a levee or sea wall that residents won't be able to see over.
"Rather than building to a number, we are building to a strategy, a mechanism in place which is going to deal with any amount of sea-level rise that occurs out here," said Dilip Trivedi, coastal engineer with Moffat & Nichol, the firm that is engineering the Treasure Island development.
