PALO ALTO — Many more Palo Alto homes and businesses than the 2,700 estimated to be vulnerable in a 100-year flood of San Francisquito Creek could be inundated if sea levels rise at least a foot, according to federal flood maps.

In an attempt to ward off such a disaster, the City Council has directed staff to plan for a 55-inch sea level rise by 2100. Staff requested that course at a May study session.

A 55-inch sea level rise would endanger properties from the Bay to Middlefield Road, between Embarcadero and San Antonio roads, according to maps from the Federal Emergency Management Agency.

Such flooding would cut off the Palo Alto Airport, Palo Alto Municipal Golf Course, the Regional Water Quality Control Plant serving multiple cities and the city’s Municipal Services Center, thus limiting some emergency response capabilities.

Bayfront levees from San Francisquito Creek to the Mountain View border do not meet today’s height and construction standards set by FEMA for 100-year floods, let alone for more potentially damaging sea level rise.

The local San Francisquito Creek Joint Powers Authority is studying the feasibility of proposals for new levees and results should be available this summer.

“The levee has to be rebuilt, but also raised,” said Phil Bobel, the city’s assistant director of public works.

A typical levee in Palo Alto stands about 10 feet high, Bobel said. Consequently, a 100-year flood in the area, or a tidal wave of 11 feet, would wash over an estimated 2,700 properties in Palo Alto, even if the sea level does not rise.

More Peninsula properties will be included in the floodplain if sea levels continue to rise.

Experts agree that the rate of sea level rise is expected to accelerate in the next century, but predictions range from 1 foot to 6 feet and beyond.

The Bay has seen 0.63 feet of sea level rise over the last century.

“We’ve got to protect our facilities,” Bobel said. “But it actually makes sense to do things incrementally given the level of uncertainty.”

One proposal would have the new levees built up to 18 feet, which assumes a mid-range estimate of sea level rise of 3 feet and takes into account higher waves from wind, Bobel said.

A 3.28-foot rise in sea level would put 220,000 Bay Area residents at risk, according to an estimate by the Pacific Institute. It’s unclear how many Palo Alto residents that figure includes.

FEMA flood maps do not currently account for sea level rise, but the 3 feet was included to begin planning for sea level rise projections for the next 50 years.

“We don’t know for sure how much it’s going to rise, so you probably wouldn’t design these levees at the extreme,” Bobel said. “You would build them to that maximum height, but what probably makes the most sense is to build a big firm base for them … so you can add height over time.”

A feasibility study to be released this summer related to the Strategy to Advance Flood protection, Ecosystems and Recreation along the Bay, or SAFER Bay, project will include options for boundaries and height of the new levees.

The jurisdictions affected by the levee update project — Palo Alto, East Palo Alto, Menlo Park, Santa Clara Valley Water District and San Mateo County Flood Control District — will have to agree on where to place the levees.

Then, “hundreds of millions of dollars” will have to be secured locally and federally for the multi-year project, Bobel said.

In coming months, Palo Alto officials could be deciding what resources to pour into the effort and how much research to devote toward developing new zoning codes and building restrictions for areas potentially impacted by sea level rise.

Vice Mayor Greg Scharff said sea level rise is a concern, but it’s important to weigh it against the city’s other priorities. He anticipates other agencies will provide more data and clarity in the next two years, so the city may be in a better place then to help address this regional issue.

“We talk about a lot of stuff at council … and then there’s no staff resources to do it,” Scharff said. “Should we be spending city time to do this at this time? Do you have the bandwidth?”

Councilman Cory Wolbach said he shares Scharff’s concerns about staff limitations and priorities, but sea level rise is too important of an issue.

“I’m not willing to drop this one,” Wolbach said. “We’re talking about an existential threat to large parts of Palo Alto, essentially irreplaceable, mission critical utilities equipment and other infrastructure.”

Some properties could potentially be affected by flooding from the Bay as well as San Francisquito Creek.

About 40 percent of the creek floodplain is also in the Bay floodplain, according to Len Materman, executive director of the San Francisquito Creek Joint Powers Authority.

The agency was formed following a combination of creek and tidal flooding in 1998 that caused millions of dollars of damage in Menlo Park, East Palo Alto and Palo Alto.

Email Jacqueline Lee at jlee1@bayareanewsgroup.com or call her at 650-391-1334; follow her at twitter.com/jleenews.