PAVILLION, Wyo. - A glass of water drawn from John Fenton's underground well outside his rural log home built against a rocky ridge looks and tastes as clear and refreshing as any bottled water.

But Fenton's water contains traces of arsenic, barium, cobalt, copper and other compounds identified in water tests that cannot be seen, smelled or tasted.

"It definitely makes you think every time you turn the faucet on," said Fenton, who farms hay on about 200 acres outside his home, located about 130 miles west of Casper.

He and other residents outside this small rural, farming community blame their water woes - and what they perceive to be the unusual health problems in their midst - on hydraulic fracturing, or "fracking," a common technique used in drilling new oil and gas wells.

Those kind of complaints have surfaced across the county in areas where energy producers use fracking. But the industry says the practice is safe, and the federal government has exempted the process from its oversight.

Fracking involves injecting water, sand and chemicals under high pressure into the ground to force open channels in deep tight sand and rock formations so that oil and gas can be more easily recovered. Fracking has been used for decades, but improvements in the process and new drilling techniques have led to its use in unlocking heretofore large, unrecoverable natural gas reserves.

Some states are investigating complaints associated with fracking, but this community in central Wyoming is the only place where the Environmental Protection Agency has opened its own investigation, according to agency officials. Here, Fenton and his neighbors formed their own advocacy group, Pavillion Area Concerned Citizens, and pleaded with the EPA and state environmental officials to test their water wells.

Preliminary EPA testing in Pavillion has found traces of toxins in some drinking water wells, but the EPA is doing more tests to determine how much is there, whether it poses a health hazard and where it came from.

EnCana Corp., which owns the Pavillion gas field, says there's no evidence its operations have caused the water problems and there could be any number of sources of the contamination in a field that has been drilled for many years.

Legislation has been introduced in Congress that would place fracking under oversight of the Environmental Protection Agency. Industry is fighting the proposal as unwarranted and as a potential killer of both jobs and the its ability to tap the nation's abundant supplies of natural gas.