I have been promoting undersea desal plants for a long time. I found something else recently that is a personal unit that converts the humidity in the air to water. While it would be less effective in So Cal, it should work on a larger scale in theory.
http://www.airwaterinternational.com/
Nuclear power will generally beat any other source hands down. And now, they are making very stable small reactors that are about the size of a shipping container. This might be a practical intermediate term solution. But in the short term, parking an aircraft carrier offshore can produce a heck of a lot of energy.
I gather in past there has been some concern about permanent desalinization plants, because they can change ocean salinity, which messes up sea life. The solution might be a more complex pipeline, that returns brine to the downstream area near the inlet.
The biggest problem is always “biologicals” that tend to clog the pipes.