If a drought lasted decades, the state could always build dozens of desalination plants, which would cost billions of dollars, said law professor Barton "Buzz" Thompson, co-director of Stanford University's Woods Institute for the Environment.

Saudi Arabia, Israel and other Middle Eastern countries depend on desalination, but water from desal plants costs roughly five times more than urban Californians pay for water now. Thompson said that makes desal projects unfeasible for most of the state now, especially when other options like recycled wastewater and conservation can provide more water at a much lower cost....
 
Over the past 10 years, he noted, Australia has been coping with a severe drought. Urban residents there cut their water demand massively, built new supply projects and survived....

Some scientists believe we are already in a megadrought, although that view is not universally accepted.

Bill Patzert, a research scientist and oceanographer at NASA's Jet Propulsion Laboratory in Pasadena, says that the West is in a 20-year drought that began in 2000. He cites the fact that a phenomenon known as a "negative Pacific decadal oscillation" is underway -- and that historically has been linked to extreme high-pressure ridges that block storms.

Such events, which cause pools of warm water in the North Pacific Ocean and cool water along the California coast, are not the result of global warming, Patzert said....