Spills related to fracking are more frequent than previously thought, a new study finds – and understanding the causes of these spills may help prevent future incidents.

In a study published Tuesday in the journal Environmental Science & Technology, a team of researchers identified 6,648 spills in Colorado, New Mexico, North Dakota, and Pennsylvania between 2005 and 2014. The researchers calculated that between 2 and 16 percent of wells will spill contaminated water, hydraulic fracturing fluids, or other substances every year, with the majority of incidents occurring in the first three years after a well becomes operational.

The definition of a spill varies from state to state, presenting a challenge for the study’s authors in comparing states. But analyzing this data, they say, is vital to addressing the challenges posed by fracking spills and makes a data-driven conversation about fracking possible.

“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 Duke University news release. “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.”

Hydraulic fracturing, better known as fracking, is an relatively new technique for extracting oil and gas. Large amounts of water, sand, and chemicals are forced underground, cracking the rocks that hold oil and gas so the resources can be extracted for use.

Fracking has created tremendous job growth in states like North Dakota and Pennsylvania and is a key component to many American energy independence strategies. But environmentalists are concerned about the side effects of the process that they say contaminates drinking water and contributes to earthquakes.

In its report about the safety of fracking, the US Environmental Protection Agency did not quantify the risk posed by the resource extraction technique, The Christian Science Monitor reported in December. It did, however, point to several cases of drinking water contamination, concluding that there was insufficient evidence to know how widespread a problem contamination was.

The EPA itself identified 457 spills across 8 states between 2006 and 2012, because it focused solely on the period when fracking was taking place, rather than looking at the entire life of the well. By providing more comprehensive data on the number of spills, the recent report may offer a starting point for determining the scope of contamination.

Industry observers, however, say many of the reported incidents had no environmental impact, possibly skewing the figures.

"The reality is that North Dakota requires that companies report any spills that are a barrel or more, even if they never impact the environment - and the vast majority of spills have not," said Katie Brown of Energy in Depth, a body funded by petroleum producing companies, the BBC reported. Many North Dakota "spills," she said, are confined to the well pad, never touching land or water.

But understanding where spills come from, and when in a well’s lifecycle they occur, is key to limiting incidents at conventional and unconventional wells alike, the researchers indicated.

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Spills are most likely during the first three years, when production volumes are highest, the researchers found. Up to 94 percent of spills happened in that time frame. And many spills – 26 percent in Colorado and 53 percent in North Dakota – occur at wells that have already had one spill.

“This study provides important insights into the frequency, volume, and cause of spills,” said Lauren Patterson, policy associate at Duke University’s Nicholas Institute for Environmental Policy Solutions and the study’s lead author. Going forward, consistent, comprehensive data collection will be essential for identifying risks and avoiding negative environmental impacts, the study concludes.