PACIFICA, Calif. -- The U.S. Geological Survey says roughly half a million Californians and $150 billion in coastal real estate are at risk of flooding by the end of the century. The problem -- rising sea levels and erosion.We found a man sprawled on a beach with no worries in Pacifica on a beautiful March day. Along Beach Boulevard, however, we also found garage doors nailed shut with sandbags in front. They tell stories of problems past and future."I already filed two claims, another, I might not have insurance," said Gioconda Egan.Egan doesn't know it yet, but her damage is already statistical, and part of something frightening. A new report from the United States Geological Survey predicts $150 billion in California flood damage by the end of this century. They are citing the reason as rising seas made more destructive by storms."San Francisco Airport, Oakland Airport, Foster City, Redwood City, Palo Alto, Oakland, Hayward, Marin County," a rogue's gallery of vulnerable locations listed Dr. Patrick Barnard, one of the authors.For context, the Loma Prieta Earthquake and California's Wildfires cost $10 billion. Storm damage exacerbated by rising seas will cost 15 times more."In fact, state-wide, San Francisco Bay accounts for two-thirds of the impact in the study," said Dr. Barnard.Pacifica already sits on a leading edge. This is the city where erosion claimed cliff-side apartment houses. When storms blow in, Egan says that despite a seawall, her house essentially becomes part of the Pacific Ocean."I have sand in my pipes and I have to hire someone to get it out of the water I was drinking."According to the study, future high water could expose some 200,000 people to regular, destructive flooding. In short, Californians, we may be talking about building a wall all over again.