I simply do not understand california's water shortage problem. They are by a frickin ocean. It's sunny nearly all year round. Solar powered or wave powered desalination is a fairly straight forward solution to this problem.
Here's an article that goes into the complications and controversies of desalination in California. http://www.mercurynews.com/science/ci_25859513/nations-large...
Then you have the problem of getting the water from the coast to the Central Valley. Given that it's going to take 20 years to build 400 miles of train track I don't hold much hope getting pipelines of a similar distance getting built in under 10 years.