US report leaves debate open on contested Wyoming fracking study

* USGS report offers no interpretation of data

* Results generally consistent with previous findings - EPA

* Wells improperly constructed - Encana

By Ayesha Rascoe

WASHINGTON, Sept 26 (Reuters) - The U.S. government on Wednesday released the latest water quality results from a Wyoming aquifer that federal regulators said was contaminated by natural gas drilling, but the data will likely do little quiet debate on the cause of the polluted groundwater.

While the United States Geological Survey report included raw data from samples it collected from a well near Pavillion, Wyoming, in April and May, the agency did not provide any analysis, leaving the information open to varying conclusions.

"Interpretation was not part of the scope of the report," USGS spokesman Dave Ozman said.

Pavillion, Wyoming was thrust into the national spotlight late last year when the Environmental Protection Agency released a draft report finding that hydraulic fracturing fluids used in natural gas drilling likely polluted groundwater in the area.

The report contradicted arguments by gas drillers that fracking fluids have never contaminated drinking water.

Advances in hydraulic fracturing, which involves injecting water, sand and chemicals underground to extract fuel, have unlocked vast shale gas resources across the nation.

Environmental groups have called for more federal regulation of fracking and some for an outright ban, saying it pollutes the air and taints groundwater.

In response to criticism from the oil and gas industry and Wyoming officials, the EPA agreed to work with the state government and the USGS to retest the water before issuing its final analysis.

The data released by the USGS on Wednesday "is generally consistent with ground water monitoring data previously released by the Environmental Protection Agency (EPA) for the Pavillion, Wyoming area," the EPA said in statement on Wednesday.

The EPA will soon release additional data it collected from the wells. Once finalized, the information from the EPA and the USGS will be submitted to for independent peer review.

Encana Corp, a Canadian company that owns the gas field near Pavillion, said there was "nothing surprising" about the data released on Wednesday.

Doug Hock, an Encana spokesman, said the main area of dispute is the conclusions drawn from the data.

Encana, which has raised concerns about the adequacy of the EPA's monitoring of wells, pointed out that the USGS was only able to sample one of the two wells.

"This goes to the heart of concerns raised by state and federal agencies, as well as Encana - EPA's wells are improperly constructed," Hock said in a statement.

The USGS said it did not sample the second well because it was not able to apply the same method it used for the first well.