Fracking injects a high-pressure mixture of water, chemicals and sand into tight rock formations to unlock hard-to-reach natural gas deposits.
A U.S. Geological Survey study last month found several of the same elements in Pavillion's groundwater as the EPA study. However, it invalidated one of EPA's two monitoring wells for yielding too small of a water sample.
The EPA has said the U.S. Geological Survey’s study is “generally consistent” with its own.
Milito said the U.S. Geological Survey study “did a better job,” adding that many of the elements EPA did discover occur naturally and are not the result of fracking.
Environmentalists contend fracking pollutes groundwater and incites seismic activity.
But industry and states say the practice is safe and that regulations have done an effective job monitoring fracking. The federal government also has praised the states’ regulatory activity, while at the same time calling for more coordinated federal oversight.
— This story was updated at 1:30 p.m. and at 4:48 p.m.