CALIFORNIA is ending its warmest winter on record, aggravating what could well be the region’s worst drought in 500 years, according to paleoclimatologists. It has devastated the state. Some small communities may run out of drinking water. Farmers are considering idling half a million acres of farmland, which could cause billions of dollars in economic damage. The last time the water supply was as low, in the 1960s, California’s population was just less than 20m. Today, the same amount of water must accommodate twice as many people—underscoring the severity of the crisis. For our chart, we scraped the end-of-month reservoir storage records from California’s Department of Water Resources for all 191 reservoirs starting in 1960, four years after the agency was formed. Each colour represents a different reservoir (though only the nine biggest are identified). The largest aren’t even in California: Lake Mead sits in Nevada and Lake Powell straddles the borders of Utah and Arizona. In the 1930s, farm workers left the Great Plains’ “Dust Bowl” for California. Now, the reverse may occur.
