Grape vines march across wires strung along rolling hills, their little trunks improbably supporting heavy black fruit. Cindy Steinbeck’s family has been farming this land since 1920. They grow Zinfandel, Viognier, Cabernet, Merlot, and Petite Syrah grapes but are best known in this area of Central California for a blend called The Crash, named after a remarkable incident in 1956, when a B-26 crash-landed 200 yards from the family home. Four of the five Air Force men aboard survived, bailing out in the nearby fields.
Now a new crash threatens, as groundwater levels beneath the vineyards plummet. California produces nearly half of U.S.-grown fruits, nuts, and vegetables, according to the state’s Department of Food and Agriculture. It is in the midst of one of the worst droughts ever recorded, with more than 80 percent of the state in extreme or exceptional drought. But so far, the Steinbeck Vineyards’ 520 acres of grapes are growing well under the hot August sun, thanks to the family’s access to all the groundwater they need: up to two acre-feet per acre per season. An acre-foot is the amount of water required to flood an acre of land one foot deep—about 326,000 gallons. The Steinbecks’ sole source of irrigation is groundwater.
However, groundwater and surface water—rivers, lakes, streams—are part of the same hydrological system. Excessive groundwater pumping can overdraft aquifers, emptying them faster than natural systems can replenish them; dry up nearby wells; allow saltwater intrusion; and draw down surface water supplies. Taking so much water out of the soil can cause the dirt to compact and the land to sink, an action called subsidence. Because land can subside as much as a foot a year in the face of aggressive pumping, it can destroy infrastructure such as irrigation canals, building foundations, roads, bridges, and pipelines.