A 12 inch crude oil pipeline breached in the vicinity of or under the Yellowstone River releasing an estimated 750 to 1,000 barrels (31,500 to 42,000 gallons) of crude oil into the river. The incident reportedly occurred at approximately 2330 on July 1, 2011 based upon low-pressure SCADA alarms at a nearby pump station within the Exxon Mobil Silvertip Pipeline System. The pipeline was shut down within 7 minutes of the initial alarm by Exxon Mobil. However, the 14 mile section of pipeline between adjacent pump stations, which crosses beneath the flooded Yellowstone River where the breach is suspected to have occurred, likely filled with river water, displacing a significant amount of oil that floated to the surface.
Several hundred residents of Laurel, MT were temporarily evacuated by the Laurel Volunteer Fire Department immediately following discovery of the spill, but were allowed to return home within several hours. The oil was observed in Billings, MT approximately 15 miles east early in the morning (0200 hours). The oil was observed at 0900 approximately 40 miles downriver (east) from the spill site. Images from the local news show the oil is widely dispersed along the banks and overland due to the flood stage conditions of the river.
