Sink or swim

Pub date February 20, 2007
WriterSarah Phelan


Click to view the San Francisco Public Utilities Commission subsidence map (PDF)

Will rising seas destroy San Francisco’s sewers? Should condos South of Market be on stilts? Could the huge Coca-Cola bottle at the Giants’ ballpark one day bubble with seawater? Can anyone explain why San Francisco still doesn’t have flood insurance?

As temperatures rise, snow packs vanish, and sea levels surge, San Francisco is waking up to its own inconvenient truth: surrounded on three sides by water, paved with concrete throughout, and erecting condo towers faster than you can say "bamboo," the city by the bay is particularly vulnerable to climate change.

With a recent California Climate Change Center report predicting sea levels will rise between four inches and three feet by 2100, San Francisco can expect increased flooding and damage to vital infrastructure and the destruction of fragile ecosystems and low-lying neighborhoods.

The evidence of impending doom is already there.

Addressing a climate change summit last month, Tom Franza, assistant general manager of the San Francisco Public Utilities Commission, revealed that seawater already tops the city’s weirs for about an hour during very high tides. Franza expects this salt water intrusion, which threatens to kill helpful microbes that digest our solid waste, to get worse as sea levels continue to rise.

So what steps is the city taking to combat climate change?

The SFPUC is already building safety valves on floodgates and pushing for environmentally friendly development toward a future where green roofs, grassy swales, and permeable sidewalks will help stop rainwater from inundating already stressed sewers. It’s also working with the Departments of Planning and Public Works to map blocks and lots that are already sinking — known officially as subsidence — and therefore especially vulnerable to flooding from rising seas.

It comes as a shock to learn that the Planning Department doesn’t already have maps of areas that are prone to floods, but zoning administrator Larry Badiner told the Guardian, "In the past, floods were related to free-running streams, and since there aren’t any in San Francisco anymore, it wasn’t an issue."

Senior planner Craig Nikitas did confirm for us that city planners are working with the SFPUC and the DPW to flag blocks and lots prone to sinking, a phenomenon associated with rising seas that city officials don’t quite understand.

"If I had to guess, I’d say [they’re sinking] because most are on sandy soils or fill and over time there’s been a settling of sand or because of subterranean flooding," Nikitas said.

As the city’s subsidence map shows, the problem is biggest in SoMa and along the bay — where concrete-intense development is on the rise.

In the future, Nikitas told us, "If a developer comes in to do something in those areas, the system will flag it, and builders should pay extra attention to drainage and elevation, using raised entrances three steps up from the street and trench drains and installing sump pumps if there’s a subterranean garage."

As small a step as subsidence mapping sounds, it’s a sea change for city planners. SFPUC principal engineer Jon Loiacono recalls how in the past he was trained to say, "If flooding happens on your property, it’s your problem."

Loiacono remembers only one instance when the SFPUC built a pump station in response to a developer’s concerns. That was almost a decade ago.

Advising developers about the perils of building in flood-prone areas sounds obvious, but with that step comes responsibility that threatens to drown the city fiscally. Asked who’ll pay for flood damage, Loiacono pointed to the Federal Emergency Management Agency.

"FEMA is currently mapping San Francisco, but the city would have to join FEMA’s flood insurance program to get coverage," Loiacono said.

Surprised that the city doesn’t already belong, the Guardian called FEMA’s Oakland-based spokesperson, Frank Mansell, who revealed San Francisco is the only city in the Bay Area that isn’t part of FEMA’s National Flood Insurance Program (NFIP). Participating in the FEMA mapping program would allow residents to qualify for federally subsidized flood insurance and get rebuilding grants after a disaster. FEMA’s Henry Chau says San Francisco will have to raise its standards "slightly higher" to join the agency’s flood insurance program.

Noting that FEMA’s San Francisco map is due this summer and includes development that lies in the city’s floodplains — development FEMA strongly discourages — Mansell said he doesn’t know why San Francisco doesn’t belong. But he does know cities that do must build to code and enact ordinances to ensure people aren’t living in flood zones. He said cities that do build in flood zones must take preventive steps such as raising buildings.

"If cities don’t comply with FEMA’s requirements, they’re put on notice and could be removed from the flood insurance program," Mansell said, adding that disasters such as Hurricane Katrina illustrate why private brokers won’t sell flood insurance.

But as FEMA digitizes and puts its maps online and predicts that 92 percent of US residents will belong to the NFIP by 2010, not everyone is singing its praises. San Francisco Bay Conservation and Development Commission executive director Will Travis faults FEMA’s flood maps for not factoring in climate change.

"Instead, FEMA looks to the past to determine floodplains. As a result, their maps are inadequate and show less inundation than is already occurring," Travis told us. The BCDC just released maps that show a two-meter sea level rise in the bay that would put the San Francisco and Oakland airports and the Giants stadium underwater.

"But we won’t allow the Giants’ ballpark to flood, SFO to be underwater, and San Francisco to become Venice," Travis said. "Instead, sea walls and levees will be built. It’ll require more investment in infrastructure and shoreline protections. The point of the maps is to show people what could happen and get them to take action. Sea level rise doesn’t belong in the realms of science fiction. It’s happening now."

With the California Climate Change Center reporting a seven-inch rise in the bay since 1900 — and the feds refusing to address the role of carbon emissions in climate change — Travis predicted that insurance companies will have the biggest impact in land use planning.

"There’s always an effort to shift costs from the private to the public sector, and from there, from the local to the state to the federal government," Travis told us. "But insurance companies are looking at potential huge losses and won’t be offering policies at all, or offering them at very high prices."

Mansell defended FEMA’s flood maps, arguing that they’re used primarily for insurance and so can’t be used for forecasting.

"We look at existing data," Mansell said. "Otherwise everyone’s premiums would be unpredictable and probably high. FEMA does encourage communities to build to the highest standard, which means the 100-year flood event that has a 1 percent chance of occurring. And FEMA doesn’t conduct the studies. The Army Corps of Engineers does."

Army Corps spokesperson Maria Or confirmed that her agency collects data at different times of the year — data showing the climate has been changing and helping forecast what those changes will mean.

"But we can’t base maps on pure speculation," Or told us. "We continuously look at new data and reanalyze the situation based on that new information. The more relevant question is how often a FEMA map is updated."

Mansell said it takes FEMA one to two years to create a flood map, using computer models, precipitation and tidal patterns, rivers and stream flows — and tracking how much concrete is laid down in an area and how much is built in a floodplain.

"Areas are mapped and remapped and show three levels of risk — low, moderate, and high risk," he said. Based on these ratings, FEMA reviews flood insurance premiums once a year.

But with FEMA the main hope of covering sea rise–related flood damage, experts such as Dr. Peter Gleick of the Oakland-based Pacific Research Institute join the BCDC’s Travis in accusing FEMA of having "failed miserably in integrating climate change into its planning."

"BCDC included climate change in their maps. FEMA did not. Why aren’t there flood maps everywhere around the country that integrate climate change?" asked Gleick, who produced a map 17 years ago showing the impact of a one-meter sea level rise on the bay.

"It’s a little depressing to have been working for two decades on this," Gleick conceded. "I’m glad people are starting to pay more attention and accept that sea level is going up, because the impacts will depend on how we react and how quickly, but we’re decades too late to prevent bad things from happening."

Outraged by President George W. Bush’s we-can’t-afford-to-unilaterally-cut-greenhouse-gases argument, Gleick said, "They’re putting short-term economic gain ahead of long-term survival." But he praised California for establishing a cap to reduce the state’s greenhouse gas emissions to 1990 levels by 2020.

In light of an Intergovernmental Panel on Climate Change report that suggests a 10- to 20-foot sea level increase in the next 1,000 years, Gleick observed, "That means hundreds and millions of people will be potential refugees. So we better reduce our greenhouse gases starting now. We can’t prevent some change, but we hope to prevent disastrous sea level change."

Gleick said he’s worried that we won’t protect low-income areas or move fast enough to prevent damage, a shortcoming that will also have devastating environmental impacts.

"Marshes and wetlands have no place to retreat, since the areas around them are already built up," he explained. "Bay Area communities should make parks, bay and coastal trails, and wetlands bigger, so they’ll have greater protection 50 years from now. And if you’re developing a building that’s supposed to last for 50 years, you need to design it now for the changes that are to come." *