To the west of the Sierra Nevada Mountains, in California’s vast, dry San Joaquin Valley, a catastrophe is unfolding. Drought-stricken growers, deprived of surface water for irrigation, are pumping ancient aquifers at a rate that will eventually extinguish them forever, should the water shortage persist. About 120 miles away, on the opposite side of the snow-starved mountain range, sits the Owens Valley. Here, the drought is merely an aggravating factor in a water crisis that began more than a century ago. In 1913, William Mulholland and the Los Angeles Department of Water and Power completed the aqueduct that tapped the river that once irrigated the high desert basin and diverted it to the citrus groves of the San Fernando Valley, 200 miles to the south. Then in 1970, the LADWP completed its second aqueduct and began pumping the valley’s groundwater until all but a single major spring had run dry.