"North Dakota had the highest rate of spills while Colorado companies reported just 11 spills per 1,000 wells annually," Nicholas Kusnetz reports for InsideClimate News. "But some or all of that difference may be due to the huge differences in what the states ask oil companies to report. North Dakota requires operators to report any spill of 42 gallons or more, while Colorado and New Mexico generally don't ask for anything smaller than 210 gallons. Texas, the nation's top oil-and-gas-producing state, wasn't even included in the study because detailed data was not easily accessible. The authors did not examine data from Oklahoma because the state had not digitized all of its information."
Researchers "found that more than half of the spills occurred while companies were storing fluids in tanks or pits or transporting them through flowlines," Kusnetz writes. "Many were repeat spills from the same wells." Kate Konschnik, a co-author of the study and director of the Harvard Environmental Policy Initiative, told Kusnetz, "It's quite scattershot the amount of information being collected, the form in which it's being collected and the way in which it's being shared with the public." (Colorado spills from tanks)