On Friday, July 1, 2011, a rupture in a pipeline operated by Exxon Mobil Corp in Montana, USA caused up to 42,000 gallons of crude oil to spill into the Yellowstone River, with cleanup efforts hampered by the river's near-flood conditions and no estimates yet on the extent of environmental damage.

http://news.blogs.cnn.com/2011/07/03/swift-water-hinders-oil-spill-cleanup-at-river/
http://www.ibtimes.com/articles/173731/20110704/exxon-oil-spill-montana-governor-oil-s-spread-yellowstone-
river.htm
http://www.latimes.com/sns-rt-oilspill-montanaexn1e761054-20110702,0,6620182.story?obref=obnetwork
http://www.latimes.com/news/nationworld/nation/la-na-oil-spill-yellowstone-20110704,0,1377467.story