For the first time, government scientists concluded that hydraulic fracturing, the process of shooting massive quantities of water and chemicals into rock to release natural gas, contaminates drinking water. The study concerns an incident in Pavillion, Wyoming, and culminates three years of research of the local aquifer.

EPA constructed two deep monitoring wells to sample water in the aquifer. The draft report indicates that ground water in the aquifer contains compounds likely associated with gas production practices, including hydraulic fracturing. EPA also re-tested private and public drinking water wells in the community. The samples were consistent with chemicals identified in earlier EPA results released in 2010 and are generally below established health and safety standards. To ensure a transparent and rigorous analysis, EPA is releasing these findings for public comment and will submit them to an independent scientific review panel. The draft findings announced today are specific to Pavillion, where the fracturing is taking place in and below the drinking water aquifer and in close proximity to drinking water wells – production conditions different from those in many other areas of the country.

Independent reports have previously shown contaminants in water due to fracking, but this is the first time the EPA has come out and said so. And while they cite Pavillion as a special case, it calls into question the surge in fracking across the country. From the Marcellus Shale to the Rocky Mountains, thousands of natural gas drilling sites have sprung up, and questions about air and water quality have persisted. Multiple examples of residents lighting the water out of their faucets on fire, and incidents of sickness in areas around the natural gas wells (many of which are in the backyards of people paid handsomely by the fracking companies for the privilege), abound.

Jim Martin, the EPA’s regional administrator in Denver, said in a statement, “EPA’s highest priority remains ensuring that Pavillion residents have access to safe drinking water. We will continue to work cooperatively with the State, Tribes, Encana (the gas company that did the fracking) and the community to secure long-term drinking water solutions. We look forward to having these findings in the draft report informed by a transparent and public review process. In consultation with the Tribes, EPA will also work with the State on additional investigation of the Pavillion field.”

Recently, a natural gas company stopped delivering shipments of clean water to the town of Dimock, in northeastern Pennsylvania, because they claimed the water quality from the local wells improved.

The samples in Wyoming came from two deep water monitoring wells, as well as private and public wells in the area. EPA found synthetic chemicals consistent with fracking fluids, as well as high levels of benzene and methane. They said that the chemicals could move through the aquifer over time and only worsen the water quality. The chemicals in the private and public water wells showed evidence of migration from drilling sites.

Tom Kenworthy from the Center for American Progress writes:

The oil and gas industry – along with some prominent federal officials – have long claimed that because fracking occurs so far below groundwater aquifers that migration of the chemicals used in fracking into drinking water supplies was not possible and had never occurred.

Last May, for example, EPA administrator Lisa Jackson testified on Capitol Hill that she was not aware “of any proven case where the fracking process itself affected water.”

Now it looks like she’s going to have to revise and extend those remarks. And it looks like the industry is facing some tough times ahead as it seeks to keep up a rush of shale gas development in fields stretching from New York to Texas.

Because fracking has become so widespread, the industry has a load of allies in Congress. So EPA will have a fight on their hands if they merely try to act on their findings. But the right of people to drink safe and clean water should outweigh those concerns.

Here’s the full 121-page EPA report. More from AP and Pro Publica.