California is locked in an epochal drought — and yet produce aisles nationwide still brim with reasonably prices fruit and vegetables from the Golden State. How does California continue providing half of U.S.-grown vegetables under such parched conditions?

Peter Gleick, president of the Pacific Institute, one of the world’s leading think tanks on water issues, broke it down for me. He says that despite the drought, California farmers will likely idle only about a half million acres this year — less than 10 percent of normal plantings, which are about 8 million acres. And most of the fallowed land will involve “low-value” crops like cotton and alfalfa (used as a feed for the dairy and beef industries) — not the stuff you eat directly, like broccoli, lettuce, and almonds.

In the Central Valley — California’s most important growing region, which spans 450 miles along the center of the state — the drought is a massive inconvenience, but it hasn’t cut farms off from water. Under ideal conditions, the great bulk of irrigation water flows through an elaborate network of canals and aqueducts that divert water from rivers (largely fed by Sierra Nevada snowmelt) to farms.