A study of 127 shallow gas wells drilled in Arkansas found no evidence that the use of hydraulic fracturing resulted in contamination of area groundwater supplies, the United States Geological Survey said today.

"This new study is important in terms of finding no significant effects on groundwater quality from shale gas development within the area of sampling," said USGS Director Marcia McNutt.

"None of the data that we have looked at as part of this study suggests that any groundwater contamination is resulting from natural gas production activities," said USGS hydrologist Tim Kresse. "However, this study does not speak to other wells that were not sampled, every chemical used during the hydraulic fracturing process, or water quality changes that might take longer to occur. It does provide a baseline to use to evaluate any possible changes in the future."

The study focused on levels of chloride found in the samples because chloride is typically found in groundwater in areas experiencing natural gas production.

"Chloride moves easily through groundwater without reacting with other ions or compounds in solution, making it is a good indicator of whether chemicals used during hydraulic fracturing are reaching groundwater. In this case, the chloride concentrations from this study were not higher than samples taken from nearby areas from 1951 through 1983," the USGS said in a statement.

The USGS study focused on samples taken from the Fayetteville Shale gas production area near Little Rock. The USGS stressed that the results of the study apply on to the samples taken from that area and do not reflect conditions that may or may not be found in other drilling areas.

Hydraulic fracturing - or "fracking" - is a process used by energy engineers for more than 60 years in which a solution of water and chemicals is injected into shale formations deep underground. Doing this often creates access to substantial deposits of oil and natural gas that would otherwise be unreachable.

The use of fracking in Pennsylvania, Texas and North Dakota has been a major factor in the unexpected growth of U.S. oil and gas production in recent years.

"The Fayetteville Shale serves as an unconventional gas reservoir across parts of six counties in north-central Arkansas, ranging in thickness from approximately 50 to 550 feet and varying in depth from approximately 1,500 to 6,500 feet below the ground surface. Drilling and production of gas wells began in 2004 and, as of April 2012, approximately 4,000 producing gas wells had been completed in the Fayetteville Shale," the USGS said.

Sen. David Vitter of Louisiana, the ranking minority member of the Senate Environment and Public Works Committee, noted the contrast between the USGS findings and those of studies by the Environmental Protection Agency in other parts of the country.

"The president and his administration have been trying to cripple hydraulic fracturing for years, even though domestic energy production has been one of the only bright spots in our economy, thanks in large part to the utilization of this technology," Vitter said. "It's certainly encouraging to see this positive result from a study using sound and transparent science to draw conclusions instead of ideology. The EPA's mishaps with fabricating evidence in Texas, Pennsylvania, and Wyoming caused an unnecessary attack on an effective, efficient and safe method of developing domestic energy. Studies like these from the USGS help set the record straight."

The USGS study's release came shortly after a much-touted movie about fracking starring Matt Damon and John Krasinski proved to be a box office failure. The movie, which portrays the hydraulic fracking process in a critical light, only brought in $4.3 million on its first weekend of widespread release.

See the complete USGS study in the embedded viewer below this story. Information about the EPA's fracking study can be found here.