The American Petroleum Institute on Oct. 18 said its analysis of data released by the U.S. Geological Survey in September suggests the U.S. Environmental Protection Agency’s water-quality investigation in Pavillion, Wyo., could be flawed.

That finding could point to bigger problems regarding the agency’s ongoing national study of the potential impacts of hydraulic fracturing on groundwater, the oil-and-gas advocacy group’s upstream director told reporters.

Eric Milito, API’s upstream director, said that EPA’s approach in the Pavillion study could forecast the approach the agency will take for its larger study of the potential impacts of hydraulic fracturing on drinking-water resources.

"Unscientific testing could produce flawed results that could result in major adverse impacts on shale energy development and the vast potential it has to contribute to U.S. jobs, U.S. economic recovery and U.S. energy security," Milito said in a conference call with reporters.

In its draft report released in December 2011, EPA said it identified levels of glycols and alcohols consistent with gas production and hydraulic-fracturing fluids as well as benzene concentrations well above Safe Drinking Water Act standards in two of the deep monitoring wells the EPA had constructed. The EPA concluded it was possible that contaminants could migrate within the aquifer and affect drinking-water safety over time.

But the American Petroleum Institute (API) says the U.S. Geological Survey (USGS) samples did not return similar results. For example, the USGS did not find the presence of several key chemical compounds, most notably glycols and 2-butoxyethanol.

According to David Ozman, USGS spokesman, the USGS study did not draw any conclusions from the sampling. "The USGS only collected the samples and provided a data set—we did no interpretation of that," Ozman said.

API’s analysis suggests the poor well construction skewed the results in the EPA’s samples. "We’ve looked closely at what the USGS did and at its data. The USGS did a better job," Milito said. "Unlike EPA, it chose not to test samples from one of the two wells that EPA drilled because that well was unable to provide representative samples due to its low-flow characteristics."

Milito added, “We do not object to EPA studying this issue, but a bad study could be counterproductive, and there are enough missteps and unanswered questions about EPA’s Pavillion sampling to raise concerns about the broader hydraulic-fracturing study.”

In an e-mailed response, the EPA said it has released new monitoring data as part of the agency's ongoing analysis of groundwater quality in the Pavillion area. According to EPA, "EPA’s new data and the USGS data are generally consistent with the monitoring data included in EPA’s December 2011 'Draft Report on Pavillion Area Groundwater Investigation.' "

EPA says it has extended the public comment period on its data through Jan. 15, 2013, to give stakeholders sufficient time to consider all data related to the Pavillion groundwater investigation. Moreover, all the data, including the USGS data, will be submitted to an independent expert peer-review panel.