Practitioners of dowsing say they use natural energy and copper sticks or wooden "divining rods" to find water. Natural energy allegedly helps dowsers find water or minerals hidden deep underground.
Government scientists disapprove of the practice, but California witches are very busy these days.
Marc Mondavi, a vineyard owner in the Napa Valley, practices dowsing. He says his phone has been ringing often as growers worry about extended years of dryness.
Deemed as the go-to water witch, Mondavi charges about $500 per site. The price rises if a well he discovers ends up pumping more than 50 gallons per minute.
Scientists say dowsers like Mondavi are often just lucky.
"There's no scientific basis to dowsing. If you want to go to a palm reader or a mentalist, then you're the same person who's going to go out and hire a dowser," said Tom Ballard, a hydrogeologist with Taber Consultants, a geological engineering firm based in West Sacramento.
"The success is really an illusion. In most places you're going to be able to drill and find some water," he said.
Meantime, John Franzia, co-owner of Bronco Wine Co., owns more vineyard land in California than anyone else and turns to dowsers often. He says he's used many technologies to find water on its 40,000-acres, but nothing has been as successful.
"I've used witchers for probably the last 15-to-20 years," Franzia said. "Seems like the witchers do the better job than guys with all the electrical equipment. I believe in them."
The Associated Press contributed to this report.