However, the report’s authors also warned the pathways could allow chemicals used in fraccing and associated flowback water to seep into the drinking water supply.
The Duke University research is only the second peer-reviewed study conducted on drinking water contamination.
It focused more on water chemistry to see the source of the water and trace its evolution.
The researchers focused on a number of valleys in six counties in northeastern Pennsylvania.
They analysed 426 shallow groundwater samples and compared them with 83 samples from underlying Appalachian brines in the deeper formations from the region.
The idea was to examine how the fluid migrated between the Marcellus shale formations and the shallow aquifers.
The paper concluded the saline contamination was not caused by hydraulic fracturing.
The conclusion is premised on two facts: the saline water was not found anywhere close to the shale gas wells; and the same type of brine water existed as far back as in the 1980s sample taken by the US Geological Survey.
On the face of it, the study appears to support the idea that fraccing does not cause water contamination.
However, the report’s authors, including lead scientist Avener Vengosh, called the report “both good news, bad news”
He noted that though there was no direct link to water contamination, the results of the Duke University research needed to be duplicated for them to be applicable to all of Pennsylvania.
The study has already attracted controversy in the scientific community.
Penn State University geosciences professor Terry Engelder, a known supporter of hydraulic fracturing, is critical of the conclusions.
He argued the Duke study “overstepped” the interpretations.
He disagreed with the premise that the fluids used in fraccing could use the same naturally occurring pathways to contaminate drinking water sources.
“When a well is fractured and starts to flow, that reduces the pressure inside the Marcellus and thus generating a pressure up the well bore,” Engelder wrote on his blog.
“The gradient is reversed. The well acts as a safety valve, relieving the pressure,” he wrote, adding that drilling would prevent the saline water from coming up.
“They don’t have an explanation for that,” he said.
This article first appeared in ILN's sister publication EnergyNewsBulletin.net.