Water witches are being hired by dozens of Californian vineyards ravaged by wildfires.
Farmers are paying more than £1,000 ($1,400) for mystics to conjure up underground water with medieval sorcery.
Water witch Rob Thompson, 53, explained how he can sense water underground with two stainless steel rods in his hands.
He is a member of the American Society of Dowsers, who also claim to locate alien life forms, treasure and stress in the body.
Rob said when he steps over groundwater, the energy surrounding him changes, causing an involuntary muscular twitch within him that makes his L-shaped rods cross.
He told the New York Times: “This is my busiest I think I’ve ever been in my life.”
The method is known as dowsing, divining, or doodlebugging and was deemed witchcraft in the 17th century.
The third generation water hunter, who also dowses oil, gas and minerals, was formerly a co-owner of one of Northern California’s largest well-drilling companies.
Doug Hill, who runs Hill Family Estate, which manages several vineyards and a winery in Napa Valley, has repeatedly hired Rob and said: “Seeing is believing, right?”
Another company that manages vineyards in Napa Valley has hired dowsers across nearly all of the more than 70 vineyards.
“I haven’t ever used a geologist to find water,” said Piña Vineyard Management’s operations manager Johnnie White.
Experts at the National Ground Water Association say water dowsing is “totally without scientific merit”.
Hydrogeologist Timothy Parker was among those who reckon their results are a mix of luck and familiarity with the landscape gained through experience.
Ben Frech, a spokesman for the National Ground Water Association, added: “There are economic issues, personal beliefs and desperation factors going into the decision to try dowsing.”
But Rob, who charges $1400 (£1020) for a visit at a site a geologist had quoted at a minimum of $6500 (£4730), said: “I just laugh at them. They don’t know the facts. I’m rarely wrong.”
Speaking just two hours drive from Silicon Valley, he added: “Those Silicon people still hire me.”
Fellow water dowser Larry Bird, 77, said: “People think you’re crazy.”
He described the sensation of being close to water as being akin to a magnetic field.
“It leaves me hot,” he said. “Just like if you short a battery.”
Sharry Hope, a longtime dowser from California, says standing over water leaves her with a “chilling sensation”.
She claims she learned one of the techniques she uses to find water on maps from a former military officer.
She swings a pendulum until it stops and points toward a “water vein,” she said. “I just mark it with a Sharpie.”
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Fifty of California’s 58 counties are under emergency drought declarations.
On farms and vineyards, a surge in well drilling and increased reliance on those wells has helped to deplete groundwater.
A wait list for a driller can be several months to a year, and the hole costs tens of thousands of dollars.