Some countries, like Israel and Saudi Arabia, rely heavily on desalination for water. However, for California, it isn’t a panacea. It’s expensive, uses copious amounts of electricity (and many forms of creating electricity require using large amounts of water, hmm) and while it might be good for coastal cities, there’s is no existing way to get the water from the desal plant on the ocean to inland communities where it is needed. Plus, of course, NIMBYs howl and squeal whenever a desal plant is proposed. Getting past the lawsuits and permitting process took the new San Diego desal plant fifteen years.
But as with so many things involving water, desalination is not that simple. Converting seawater into drinking water is very expensive, it consumes a lot of electricity and it comes with a host of potentially unsavory environmental impacts.
First of all, it’s very expensive. Second, it takes a lot of energy, and it’s hard to find places where you can site desal facilities that are acceptable to the local community and people who are concerned about marine resources.
The other point is that a lot of the places that really need desal don’t have access to the State Water Project. Because of where it’s going to happen – places like Monterey and Carmel or Moss Landing – it’s not going to reduce demand on the State Water Project or Central Valley Project appreciably, if at all.