The Democrat, surrounded at a Statehouse ceremony by environmentalists and Twinfield Union School students who pushed for the ban, said the law may help Vermont set an example for other states. The ban may be largely symbolic, though, because there is believed to be little to no natural gas or oil beneath the surface in Vermont.
The gas drilling technique, called hydraulic fracturing, or fracking, involves the high-pressure injection of water and chemicals into the ground to split rock apart and release natural gas or oil.
It's being used extensively in the rapidly expanding natural gas industry in several states. Critics have blamed the practice for contaminating drinking water wells of some residents living near the drilling operations, but natural gas industry officials dispute those claims.
Shumlin said the increased amounts of natural gas obtainable through hydraulic fracturing were not worth the risk to drinking water supplies.
In the coming generation or two, "drinking water will be more valuable than oil or natural gas," Shumlin said.
"Human beings survived for thousands and thousands of years without oil and without natural gas," he said. "We have never known humanity or life on this plant to survive without clean water.
Shumlin then appeared to contradict himself, saying other states should emulate Vermont's ban on hydraulic fracturing but also should be the "guinea pigs" for testing the process.
"I hope other states will follow us," he said. "The science on fracking is uncertain at best. Let the other states be the guinea pigs. Let the Green Mountain State preserve its clean water, its lakes, its rivers and its quality of life."
The Vermont Public Interest Research Group's executive director, Paul Burns, who spoke at the bill signing, said that he had traveled Tuesday to a rally in Albany, N.Y., put on by critics of hydraulic fracturing and that the crowd there was buoyed by the Vermont action. New York is one of the states, along with Pennsylvania, Ohio and West Virginia, where gas drillers have flocked because of the Marcellus Shale, a massive underground rock formation estimated to contain 84 trillion cubic feet of recoverable natural gas, enough to supply the nation's gas-burning electrical plants for more than a decade.
Industry groups panned the Vermont ban.
The American Petroleum Institute said Vermont was pursuing an "irresponsible path that ignores three major needs: jobs, government revenue and energy security."
America's Natural Gas Alliance said the Vermont law was "poor policy that ignores fact, science and technology." It said natural gas is being produced "safely and responsibly."