Commentary It’s only December, and several major storm systems have already passed through California. These storms are encouraging news in a parched state where multi-year droughts have been declared four times just since 2000. But most of the runoff from these storms quickly ends up in the Pacific Ocean. In a 2017 study (pdf), the California Public Policy Institute estimated so-called “uncaptured water, river water in excess of the total volume diverted by water users or kept instream for system and ecosystem purposes,” averaged over 11 million acre feet over the preceding twenty years. Back in the 1950s and 1960s, Californians built the most impressive system for interbasin water transfers on Earth. Each year, millions of acre feet of water are transferred from the Sacramento-San Joaquin and Colorado River watersheds into massive coastal cities: the San Francisco Bay Area, greater Los Angeles, and San Diego. This water is diverted from …