Groundwater use in California “practically defines the term unsustainable,” says a California hydrologist. Some fields in the once-lush Central Valley have dropped 30 feet as all the water is sucked from beneath them. Dust clouds obscure the snow-starved Sierra Nevada Mountains that normally trickle water through the summer. Even though it’s only 2 percent of the nation’s farmland, the valley produces half of U.S. fruits and nuts by value. After three years of thirst in California, hunger elsewhere is sure to follow.