First, the earth around the rural town of Dimock, Pa., was cracked open as gas drillers used fracking to tap the vast energy supplies of the Marcellus Shale.

Then, in April 2009, residents there lost their access to fresh drinking water. Wells turned fetid. Some blew up. Tap water caught fire.

Now, nearly three years later — and after a string of lawsuits and state investigations has ushered Dimock to the forefront of the environmental debate over drilling but failed to resolve the water problem — the Environmental Protection Agency is stepping in to supply drinking water itself.

On Friday, the agency announced it would bring tanks of drinking water to four homes, including that of Julie Sautner, whom ProPublica first interviewed about her water problems in 2009.

“Data reviewed by EPA indicates that residents’ well water contains levels of contaminants that pose a health concern,” the agency said in a statement. Tests showed dangerous levels of arsenic, a carcinogen, as well as glycols and barium in at least four wells, and the EPA is apparently concerned that the contamination may be more widespread.

According to the statement, the EPA plans to test the water supplies in 60 additional homes for hazardous substances.

In 2009, Pennsylvania officials charged Cabot Oil & Gas, the company that drilled the wells in Dimock, with several violations it said had contributed to methane gas leaking out of the gas wells and into drinking water. For a time, Cabot supplied drinking water to a number of homes in the area but then stopped.

The EPA has waded into the Dimock issues slowly over the past few months, provoking a defensive stance from the state’s lead environmental regulator, who earlier this month called the EPA’s understanding of the Dimock situation “rudimentary.”

But the state has not undertaken the scope of water analysis the EPA now plans to do, and until the EPA stepped in Friday, Dimock residents had found little resolution.

Environmental groups are applauding the EPA’s move. "This finding confirms what Dimock residents have said for months, that the Pennsylvania Department of Environmental Protection should have never allowed Cabot to end deliveries of clean water," said Environmental Working Group senior counsel Dusty Horwitt.

But they also say the time has come for the EPA to address water contamination concerns in other communities across the country where residents say drilling has harmed their water.

In December, the EPA concluded that fracking was likely to blame for a similar rash of groundwater contamination in Pavillion, Wyo. The agency is conducting a multiyear national study of fracking’s effects on water supplies.

We have previously reported about water and drilling concerns in parts of western Wyoming, as well as central and southern Colorado, Texas, Ohio and elsewhere.