ST. HELENA, Calif. — With California in the grips of drought, farmers throughout the state are using a mysterious and some say foolhardy tool for locating underground water: dowsers, or water witches.

Practitioners of dowsing use rudimentary tools — usually copper sticks or wooden “divining rods” that resemble large wishbones — and what they describe as a natural energy to find water or minerals underground.

While both state and federal water scientists disapprove of dowsing, California “witchers” are busy as farmers seek to drill more groundwater wells because of the state’s record drought that persists despite recent rain.

The nation’s fourth-largest winemaker, Bronco Wine, says it uses dowsers on its 40,000 acres of California vineyards, and dozens of smaller farmers and homeowners looking for wells on their property also pay for dowsers. Nationwide, the American Society of Dowsers boasts dozens of local chapters, which meet annually at a conference.