US report highlights fracking spill risk

The analysis, published in Environmental Science & Technology, is said to have identified 6,648 spills recorded across Colorado, New Mexico, North Dakota and Pennsylvania over a 10-year period.

"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.

According to Duke University, researchers examined state-level spill data to characterise spills associated with unconventional oil and gas development at 31,481 wells hydraulically fractured, or fracked, in the four states between 2005 and 2014.

"State spill data holds great promise for risk identification and mitigation," Patterson said in a statement. "However, reporting requirements differ across states, requiring considerable effort to make the data usable for analysis."

North Dakota reported the highest spill rate, with 4,453 incidents, followed by Pennsylvania at 1,293, Colorado at 476 and New Mexico at 426. The University added that the number of spills reported is partly a reflection of the reporting requirements set by each state: North Dakota required reporting smaller spills (42 gallons or more) than Colorado and New Mexico (210 gallons or more).