An oil spill involving more than 20,000 gallons of oil is under investigation in North Dakota.
The Associated Press reported that vibration in an oil tank reportedly caused a bolt to come off and spill the more than 542 barrels of oil in western North Dakota near Watford City.
The North Dakota Oil and Gas Division said the spill happened over the weekend at a Newfield Production Co. operation and involved 20,160 gallons of oil. The spilled oil was recovered and contained by dikes according to state Oil and Gas Division spokeswoman Katie Haarsager.
A state inspector was on site monitoring the cleanup and the remediation.