Efforts to stem the '' Deepwater Horizon '' oil spill were ongoing from the time that the '' Deepwater Horizon '' exploded on 4/20/2010 until the well was sealed by a cap on July 15 , 2010 . Various species of dolphins and other mammals ( 61 casualties ) , birds ( 2,095 casualties ) , and the endangered sea turtles ( 467 casualties ) have been killed either directly or indirectly by the oil spill . The '' Deepwater Horizon '' spill has surpassed in volume the 1989 '' Exxon Valdez '' oil spill as the largest ever to originate in U.S.-controlled waters ; it is comparable to the 1979 Ixtoc I oil spill in total volume released ( Ixtoc discharged to ; as of mid-July 2010 , Deepwater Horizon has spilled to )
Ixtoc I oil spill
Ixtoc I oil spill
Efforts to stem the Deepwater Horizon oil spill