All this pointing and "feeling" has led to real tension between scientists and dowsers. Some of it, undoubtedly, flows from the fact that the witches indeed have a measure of success in locating underground water, which has led many landowners in search of water to call on dowsers in place of, or in addition to, scientists.
The scientists push back.
"To locate ground water accurately ... as to depth, quantity and quality, a number of techniques must be used. Hydrologic, geologic, and geophysical knowledge is needed to determine the depths and extent of the different water-bearing strata and the quantity and quality of water found in each. The area must be thoroughly tested and studied to determine these facts," the USGS says.
"Compared to dowsing," Timothy Parker, a California groundwater management consultant and hydrogeologist, told The New York Times, "which is a person with a stick."
The USGS and others suggest that the added expense of calling in water witches, though reportedly less than a certified scientist, is simply not worth it.
For his part, Jarvis maintains that geologists and other scientists (including hydrologists) are more adept at finding the water. But witches, he says, are more trusted by farmers and other landowners.
Jarvis regularly lectures on water witching (a recent webinar conducted for the American Water Resources Association was entitled, "Finding Water the Ol' Timey Way") and has some firsthand knowledge of it.
Early on in his more than 30-year career, he regularly encountered dowsers — he still does — and, after joining the American Society of Dowsers (ASD), someone found his name on a list of dowsers and, much to his surprise, asked him to come witch a well. So he did.
After getting the lay of the land, he picked a spot. It turned out OK. Still, "it didn't make any sense to me as a geologist," he says.
Despite the head-butting between Old World and new science, Jarvis now is rather neutral about the idea of dowsing and water witching. He's never surprised when someone finds underground water through non-scientific methods — again, there's a lot of groundwater out there — but he says that the act of striking water, of bringing it to the surface, remains "magical."
"I look at it this way," Jarvis says. "They have a 400-year jump on us [dowsers versus hydrologists and hydrogeologists]. To me, it's part of the folklore. It's easy to dismiss it. But if you do, you dismiss that folklore. You dismiss a part of your history."