Infrastructure protectionSilicon Valley braces for floods, storm surges caused by sea level rise

A new analysis from New America Media and Climate Central found that $36.5 billion in property and at least 145,000 California residents could be directly affected in the next thirty years from flooding caused by sea level rise. San Mateo County, home to major corporations including Facebook, Oracle, and Genentech in Palo Alto, and the low-income population of East Palo Alto, would be the most affected. The region suffered heavy damage in a February 1998 flood and is located on land less than three feet above the high tide line.

“Sea level rise means more floods, reaching higher — and that’s already happening today, long before the threat of permanent submersion,” said Dr. Ben Strauss, study lead and Climate Central’s vice president for climate impacts, in a statement. “Northern California will likely break local records before most of the rest of the nation.”

Columbus CEO reports that climate change will cause the sea level to rise by one foot by 2050, and by about three feet by 2100. As sea level rise, risk of high tides and storm surges could destroy protective structures, leading to severe flooding. “It’s not just gradual sea level rise (that’s a problem),” said Jeremy Lowe, a scientist who studies estuaries and wetlands with Environmental Science Associates. “It’s when we have a high tide and a storm and big waves in the Bay. That’s when we are going to have flooding and those events are going to be more frequent and they are going to affect us sooner.”

East Palo Alto City manager Magda Gonzalez said the median annual income of residents lie below $48,000; along with a high unemployment rate which is about triple that of the entire San Mateo County (5 percent) and diminishing property values, the city does not have the tax revenue needed to support protective measures to reduce the effects of mass flooding. The levee currently protecting the city from the San Francisquito Creek gives a twelve-year-flood protection, while the standard is 100 years.

East Palo Alto is now part of a regional partnership to protect the area from future floods by constructing a new $37 million levee and an addition of fifteen acres of tidal wetlands to buffer against the rising sea and storm surges. The San Francisquito Creek Joint Powers Authority, headed by Len Materman, also includes Menlo Park, Palo Alto, and two countywide agencies.

“When there is a big storm event, a lot of water is coming down the channel,” Materman said. “If it is concurrent with high tide, that significantly increases the amount of water in the channel in East Palo Alto and increases flooding. With sea level rise that is going to be made worse.” The new levee will protect against a 100 year flood- which has a 1 percent chance of occurring each year- and twenty-six inches of sea rise. “The National Research Council had three different scenarios: aggressive, moderate and smallest scenario,” Materman said. “We chose the most aggressive. In 50 years, 26 inches [of sea rise] is pretty large for a 50-year number. I feel comfortable that we’re on the right track.”

The proposed project could be built in two years, but it faces some hurdles, including a lengthy process to obtain required permits. In March, the San Francisquito Creek Joint Powers Authority decided to appeal a February decision by the Regional Water Quality Control Board to deny a permit for the project. The water board is requesting a new application that analyzes at least two other design alternatives and more technical data, including “all of the hydrologic and hydraulic modeling performed for the various alternatives evaluated for the Project.”