A new report from Duke University found 6,648 spills at hydraulically fractured oil and gas wells were reported across Colorado, New Mexico, North Dakota and Pennsylvania over 10 years.
The spills, which occurred between 2005 and 2014 at 31,481 wells, contained "hydrocarbons, chemical-laden water, hydraulic fracturing fluids and other substances," the study reports.
"As this form of energy production increases, state efforts to reduce spill risk could benefit from making data more uniform and accessible to better provide... important information on where to target efforts for locating and preventing future spills," said lead author Lauren Patterson, a policy associate at Duke, in a statement.
The study looked at looked at spills from the entire oil and gas production cycle. Another study from the EPA that looked at fracking spills alone found 457 incidents reported from 2006 to 2012.
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"Understanding spills at all stages of well development is important because preparing for hydraulic fracturing requires the transport of more materials to and from well sites and storage of these materials on site," Patterson said. "Investigating all stages helps to shed further light on the spills that can occur at all types of wells - not just unconventional ones."
Half the spills in the study occurred during storage and moving fluids through pipelines.
North Dakota reported the most spills 4,453, then Pennsylvania with 1,293, Colorado with 476 and New Mexico with 427. The wide variation is in part due to different requirements for reporting (for example, North Dakota mandates reporting spills of 42 gallons or more while Colorado and New Mexico require spills of 210 gallons or more to be reported.)
The risk of a spill was highest in the first three years of a well's operation, the researchers wrote, "when wells were drilled, completed, and had their largest production volumes."
From a quarter to more than half of spills occurred at wells that had previous spills, which researchers said called for more attention.
"Analyses like this one are so important, to define and mitigate risk to water supplies and human health," said Kate Konschnik, director of the Harvard Law School's Environmental Policy Initiative, in a statement. "Writing state reporting rules with these factors in mind is critical, to ensure that the right data are available - and in an accessible format - for industry, states and the research community."
The study was published Tuesday in the journal Environmental Science & Technology.
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