Analysis of deep monitoring wells by the Environmental Protection Agency Wyoming aquifer near the Pavillion natural gas field revealed glycols and other synthetic chemicals associated with hydraulic fracturing.
The American Petroleum Institute said the EPA analysis was "unscientific."
"If EPA thinks its investigation at Pavillion has produced scientifically useful information, then it may proceed in the same inexpert way at other testing sites, assume it is getting additional useful information, and employ that information to justify changes in public policy," said API's upstream director Eric Milito in a statement.
API said an investigation from the U.S. Geological Survey was better than the EPA's because it didn't sample low-flowing monitoring wells.
"In the well from which USGS did draw samples, it found the samples did not contain several compounds of interest previously identified by the EPA," the trade group said.
Early this month, the Sierra Club, Earthworks and the Natural Resources Defense Council said they confirmed the EPA study was able to highlight risks associated with hydraulic fracturing.
Energy companies working shale natural resources utilize hydraulic fracturing, known also as fracking. The process uses abrasives and chemicals to extract natural resources from rock formations. Some of the chemicals are considered harmful to the environment.
Energy in Depth, a group formed by several energy-industry organizations, said is found more than 50 individual measurements in the EPA report that were discredited by the USGS.