Hydraulic fracturing has contaminated some drinking water sources but the damage is not widespread, according to a landmark U.S. study of water pollution risks that has supporters of the drilling method declaring victory and foes saying it revealed reason for concern.
The draft analysis by the Environmental Protection Agency, released Thursday after three years of study, looked at possible ways fracking could contaminate drinking water, from spills of fracking fluids to wastewater disposal.
“We conclude there are above and below ground mechanisms by which hydraulic fracturing activities have the potential to impact drinking water resources,” the EPA said in the report. But, “we did not find evidence that these mechanisms have led to widespread, systemic impacts on drinking water resources.”
The study was commissioned by Congress and represents the most comprehensive assessment yet of the safety of fracking, a technique that has led to a boom in domestic oil and gas production but also spawned persistent complaints about pollution. Fracking involves the injection of water, sand and chemicals underground to break apart shale rock and free trapped oil or gas.
Thomas Burke, the EPA’s top science adviser, told reporters that given thousands of wells drilled and fracked in the last few years, “the number of documented impacts on groundwater resources is relatively low.”
Still, it’s not accurate to say that there have been no cases of contamination, he said.
“There are instances where the fracking activity itself” led to water pollution, he said.
The EPA looked at the potential for spills of fracking fluids, poor wastewater disposal or migration of chemicals shot underground.
The American Petroleum Institute, an industry trade group, said the study was a validation of the safety of fracking. It said it showed existing oversight from state regulators is working.
“Hydraulic fracturing is being done safely under the strong environmental stewardship of state regulators and industry best practices,” Erik Milito, API’s upstream group director, said in an e-mail.
When the study began much of the focus was on the risk that chemicals mixed in fracking fluids could flow through underground fissures and into underground water reservoirs. The study results show that might not be the biggest risk.
“The process of fracking itself is one risk factor. But in fact it’s not the biggest one,” said Mark Brownstein, vice president of the Environmental Defense Fund. “Ongoing physical integrity of the wells and handling the millions of gallons of wastewater coming back to the surface after fracking, over the lifetime of each well, are even bigger challenges.”
Amy Mall, a senior policy analyst for the Natural Resources Defense Council, said the study provides “solid science that fracking has contaminated drinking water across the country.”
Mall said, however, that a lack of cooperation from industry meant EPA lacked key data necessary to fully assess its safety.
Another environmental group, Earthworks, said EPA analysis points to the need for regulation.
“Now the Obama administration, Congress, and state governments must act on that information to protect our drinking water, and stop perpetuating the oil and gas industry’s myth that fracking is safe,” said Lauren Pagel, Earthwork’s policy director, in an e-mail.
The EPA said it analyzed more than 950 sources of information. The study included an analysis of industry-backed disclosures of the chemicals used in fracking, case-studies of local communities where homeowners feared their water wells were contaminated and a review of well construction.
The EPA said as many as 30,000 fracked wells were drilled annually between 2011 to 2014, as oil production reached its highest level in more than three decades.
“People in favor of drilling will see this as vindication,” said Rob Jackson, a Stanford University professor who has tested drinking water near fracking sites in Texas, Pennsylvania and other states. “People opposed to it will see this as a whitewash.”