The reality of desalination is that apart from Karlsbad where they are already building one, there are very few places you could build a desalination plant and associated power plant without someone (rich person or environmental group) getting lawyered up.

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.