Many have hoped that desalination plants up and down the coast of California could produce enough water for much of California. Nope. It’s not even close. Were California to build every proposed desal plant, it would account for a mere 1% of what California needs. Plus, there’s no easy way to get that water to where it’s needed which mostly is the Sacramento Delta. Also, the Carlsbad desal plant near San Diego took fifteen years to be built, due to regulatory hurdles and NIMBY lawsuits. New plants won’t happen fast.
There is just one proposed California desal plant that will cut local surface water needs. Only one. Also, desalination is expensive, requires continual maintenance, and uses substantial amounts of electricity which – wait for it – often requires water for cooling. And forget about using solar panels on site to power it on a beach in California. The specter of acres of solar panels on a California beach would cause NIMBYs to wallpaper the project with lawsuits.
There is just one proposed desalination facility that will in fact reduce strain on a local freshwater ecosystem. The proposed California American Water plant near Monterey will directly reduce surface water withdrawals from the Carmel River. Those reduced withdrawals, however, were mandated by the state more than 20 years ago. Such mandates with direct links to meaningful improvements in stream flow should certainly be a factor in deciding whether to build a desalination plant.
While often Californians are persuaded to consider desalination as a way to future water supply security using Israel and Western Australia as examples, one should remember that California is a highly populated state of about 40 million compared to 8 million in Israel and 2.6 million in Western Australia.
Seawater desalination, while can be a very small part of water supply portfolio of some of California’s coastal regions, will not be a significant part of the pie. The math is just not there.