Oil and gas companies in North Dakota face a new threat in the constant battle to maintain safe operations - roving bovine.
A cow is the presumed culprit in a natural gas liquids spill on Thursday near a tributary of the Little Missouri River in the oil-rich US state, according to an Associated Press report.
The beast is thought to have rubbed against a tank valve a few days earlier, sparking the spill of about 20 barrels of NGLs near south of Medora in western North Dakota.
The site is operated by a subsidiary of Oklahoma-based OneOK.
Clean-up is underway and absorbent booms have been placed in the nearby Sully Creek as a precaution, the news wire quoted State Environmental Health Chief Dave Glatt as saying.
There were no reports of injured bovine.
A OneOK spokeswoman explained what happened:
"Many of our facilities are in rural, fenced in, secure locations. However, some valves are located in more open settings which allows for the possibility of wildlife to come into contact with equipment, such as valves."
She said the leaking valve has had clasps and a closure cap installed "to prevent any future, unintended releases".
"We are in the process of evaluating all other valves," she said in an emailed statement.
There were no updates available on the spill itself.
Glatt told the AP that the cow was either curious or just needed to scratch an itch.
"They just get rubbing along those valves and they open up," Glatt told the news wire. "Sometimes they need to scratch their backs and they open those valves."
Glatt said this is not the first incident of a renegade cow causing havoc, and operators should already be aware of the potential damage animals can cause on the sprawling ranches of North Dakota.
"They need to make sure their valves are locked," Glatt told the AP. "They should kind of already know that because it can create issues for them."
Glatt also said he has known cows to show a taste for hydrocarbons: "They like oil and they eat that stuff up."