I just got done reading an article about how a major rainstorm can hit California and cause $725 billion dollars in damage. http://pubs.usgs.gov/of/2010/1312/ USGS called it ARkStorm (for Atmospheric River 1,000) (coincidental that they discussed a forty day rain event?). The conclusion to this report was that the government needs to figure out if it should fork out the money up front for infrastructure mitigation or pay later for recovery. They also realize they need to educate the public about the risk of such an extreme disaster (perhaps a bug-out bag, a place to go, and good insurance).
What a surprise. Just like it was a surprise that Hurricane Katrina caused levees to break which inundated homes that were built below sea level. A large portion of the Central Valley is 25 feet above sea level or lower. It's no wonder that it floods and has great potential to flood. Tulare Lake, ele.200 feet, is no longer a lake (although it was in 1997 due to flooding). It was about 600 square miles in size, the largest freshwater lake in the US west of the Great Lakes. By the end of the 1800s the lake was just about gone due to water diversions throughout the valley. Do people think that 1997 was a fluke and the lake won't ever return? That was a rain on snow event which caused the snow pack in the mountains to quickly melt. What about those people who live in Sacramento or Stockton? Do you know why the older houses in downtown have a dozen steps to climb to get to the first floor? It's because the place used to flood almost yearly. People raised the houses so the first floor wouldn't flood. Sure the basement did, but not the main living area.
The valley is a great place to farm. It has some of the most fertile soil in the world, and some of the best weather for growing just about everything. But it's no place for large subdivisions of homes, unless of course you expect the government to step in and bail you out when it floods. I suppose that's why I wouldn't live there. My property is about 400 feet elevation. Perhaps someday I'll have that lakefront property that I've always dreamed of. I'll be glad the roads won't be passable for everyone else to get here.