California’s Central Valley — one of the richest agricultural regions in the world — is sinking. During a recent intense drought, from 2012 to 2016, parts of the valley sank as much as 60 centimeters per year. “It isn’t like an earthquake; it doesn’t happen, boom,” says Claudia Faunt, a hydrologist with the U.S. Geological Survey. But it is evidence of a slow-motion disaster, the result of the region’s insatiable thirst for groundwater.