"Tesoro Logistics and North Dakota didn't quickly tell the public about an oil pipeline spill, and the firm doesn't know when it started."
"WASHINGTON — About sundown one Sunday in September, North Dakota farmer Steven Jensen noticed that his combine was running over wet, squishy earth in a wheat field he was harvesting. When he took a closer look, he saw that oil had coated the wheels and that it was bubbling up about 6 inches high in spots.
That was Sept. 29; Jensen contacted authorities immediately. At least 20,600 barrels of oil leaked onto the Jensens' land from a pipeline owned by Tesoro Logistics, one of the largest land-based spills in recent history. Neither the pipeline company nor the state informed the public of the spill for 11 days.
Since then, why there was a delay in disclosure has proved to be one of several fundamental questions that Tesoro and state authorities have yet to answer. No one knows how long the pipeline was leaking before Jensen discovered it, nor why sensors on the pipe failed to detect the leak. Neither the state nor the company could say what the pipeline's capacity was. Experts on pipeline spills question the accuracy of Tesoro's leak estimate, disputing its methodology."