A group of Pennsylvania residents on Tuesday petitioned the Environmental Protection Agency to reopen an investigation into water quality in Dimock, Susquehanna County, after publication of an internal agency analysis that linked gas drilling to methane leaks.

Ray Kemble, who lives in the town, and Craig Stevens, who lives nearby, delivered a petition they said was signed by 60,000 people to EPA employees in Washington. They carried a gallon of brown water they said came from a well used by Kemble.

"Even though I don't like to call the federal government in, you guys are our last hope," Stevens told EPA staffers outside the agency's headquarters. "We need you to tell the truth about fracking."

Dimock, the northeast Pennsylvania town featured in the film Gasland, has become a symbol for opponents questioning the safety of hydraulic fracturing, in which water, sand and chemicals are shot underground to release gas trapped in shale deep underground.

In 2010, state regulators said drilling by Cabot Oil & Gas Corp. near Dimock had contaminated local wells, a finding disputed by the company. The subsequent EPA investigation, concluded last year, found the water posed no health risks to town residents.

In late July, environmentalists uncovered an unreleased PowerPoint presentation by an EPA employee that said fracking caused methane to leak into drinking-water aquifers. The EPA said the findings in the presentation were preliminary and more study was needed. Cabot said water-well issues are the result of natural gas migration, not drilling or fracking.

Following publication of the internal report, the critics of the gas-production technique say the EPA needs to return to Dimock and reopen its probe into what has happened there.

"We will review the petition," Alisha Johnson, an agency spokeswoman who met with Kemble and Stevens, said in an e-mail.