On September 15, 2014, the U.S. Department of Energy’s National Energy Technology Laboratory (DOE) released a report of a major federal study titled “An Evaluation of Fracture Growth and Gas/Fluid Migration as Horizontal Marcellus Shale Gas Wells Are Hydraulically Fractured in Greene County, Pennsylvania.” The study concluded that there was no evidence that hydraulic fracturing (fracking) caused the contamination of drinking water at a study location in Pennsylvania.

Fracking is a method of extracting oil and gas deposits that are inaccessible by conventional drilling. Fracking uses millions of gallons of high-pressure water mixed with sand and chemicals to break apart rocks rich in oil and gas. Fracking has become increasingly common over the past decade and is largely responsible for the current energy boom in the United States, but the practice has led to concerns regarding potential groundwater contamination.

After studying one particular site in western Pennsylvania for 18 months, the DOE determined that neither fracking chemicals nor brine water from the gas drilling process had contaminated area drinking water. The report said that the chemicals used in fracking remained approximately 5,000 feet below drinking water supplies. The study marked the first occasion where a company agreed to have its fracking operations independently monitored.

The DOE acknowledged, however, that fracking at other sites may have different results due to variation in geology or drilling methods. The site studied by the DOE was limited to six wells at one location in western Pennsylvania. It should be noted that Pennsylvania regulators have noted instances where surface spills of chemicals or wastewater damaged drinking water supplies.

At the same time the DOE study was released, scientists from Duke, Ohio State, Stanford, Dartmouth and the University of Rochester released a study in Proceedings of the National Academy of Sciences titled “Noble gases identify the mechanisms of fugitive gas contamination in drinking-water wells overlying the Marcellus and Barnett Shales.” The study, which took place in the Marcellus Shale in Pennsylvania and in the Barnett Shale in Texas, concluded that defective construction of the wells caused pollution, but not the fracking process itself. This study focused on 113 drinking water wells in Pennsylvania and 20 wells in Texas that were known to have elevated levels of methane. An analysis of gas geochemistry data implicated leaks through annulus cement in four cases, production casing in three cases and underground well failure in one case. The study authors concluded that gas migration induced by fracking deep underground was not found to be a cause of contamination.

These studies suggest that the use of fracking as a method of extracting oil and gas deposits is not responsible for groundwater contamination. In those rare instances where groundwater contamination occurs, it is more likely due to faulty well construction rather than gas migration induced by fracking, which takes place far below any drinking water aquifer. The concerns identified in the universities’ study are not unique to fracking, but to oil and gas exploration generally.