The EPA has issued a draft report confirming what many environmental groups have long suspected: Natural gas drilling is causing groundwater contamination.

The agency conducted its water testing in Pavilion, WY - a town that is replete with gas wells, and where residents have long complained of sickness after drinking their water. The agency's samples, collected between March of 2009 and April of 2011, found high concentrations of diesel fuel, methane, benzene and chloride. Those chemicals are found in the fluids used in hydrofracking, the process that natural gas companies use to extract gas from shale formations deep underground.

The findings don't mean that the EPA will find the same problems in the Marcellus Shale region, which stretches across New York and Pennsylvania and includes slivers of Maryland and Virginia. Wyoming sits above a different shale formation. But the study's findings do give scientific credibility to what a lot of residents across rural Pennsylvania have endured since drilling began about four years ago. Many who live near drilling sites report finding dead fish in their streams after drilling fluid spilled, or dead or sick farm animals after drilling fluids contaminated their ponds. Individual companies across Pennsylvania have been fined, cited and sued for causing contamination.

Several environmental groups, including the Chesapeake Bay Foundation, have filed a petition under the National Environmental Policy Act for a federal analysis on the effects of fracking in the Bay watershed.

The EPA emphasized the findings were only a draft, and the study still needs to undergo a public comment period and a peer review. But immediately, politicians on both sides of the aisle began using the preliminary findings to bolster their case.

Many Republicans, who would like drilling to be controlled on a state-by-state basis, excoriated the EPA for releasing incomplete data and demanded a more rigorous peer-review process. They said the EPA did not sample enough wells and worried the conclusions would harm Wyoming's economy, which relies heavily on natural gas drilling.

Many Democrats, meanwhile, said the finding bolstered their efforts to restrict natural gas drilling in some states, and better regulate it nationwide. Democrats in New York are pushing for the passage of an act that would require drilling companies to not only disclose which chemicals are in the fracking fluids used to extract the gas from the rock, but their amounts.

Discussions continue in New York on whether to allow fracking to resume. The state put in a moratorium on drilling in 2008, but Gov. Andrew Cuomo would like to see it lifted, primarily because upstate New York could use the economic boost. The Delaware River Basin Commission has not yet voted on whether to allow fracking in its watershed.

Environmental groups are also stepping up their own investigations of fracking. CBF hired a videographer to document air emissions at several fracking sites, then sent a letter with their findings to the EPA. The Environmental Working Group, meanwhile, just released "Drilling Doublespeak," a report on how landowners have been deceived into leasing their property for drilling. Josh Fox, director of the film "Gasland," said he is working on a follow-up, "Gasland II." The first film, which showed faucets on fire because of methane in the water, was nominated for an Oscar in 2011.