An ExxonMobil oil pipeline that ruptured beneath the Yellowstone River has fouled more than 150 miles of the waterway between Laurel and Miles City. Exxon officials have not said what caused the leak, but in a morning press conference Saturday, Yellowstone County officials noted that the high level of the river, the speed of the water and quickly moving debris all may be factors. The oil slick started just east of the Laurel Bridge late Friday night .. readmore.