Business leaders and U.S. Sen. Dianne Feinstein are launching a $1 billion fundraising effort designed to prevent some of Silicon Valley's leading technology companies from going underwater _ literally.

The corporate campuses of Facebook, Google and other high-tech ventures sit on land that once was part of San Francisco Bay.

Planners say those sites and thousands of homes are at risk of catastrophic flooding due to a climate change-fueled sea level rise.

For protection, Feinstein is joining a coalition of business groups on Thursday to discuss replacing the century-old levees that contain the bay's tidal waters with a stronger levee system.

Steve McCormick, president of the Gordon and Betty Moore Foundation, says the coalition anticipates that half of the money for the project would come from the federal government and another quarter from the state.