Efforts to stem the Deepwater Horizon oil spill Efforts to stem the Deepwater Horizon oil spill 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
Rayong oil spill study found that Corexit increases the toxicity of oil by 52 times. It can remain in the ecological food chain for many years and cause widespread and long-lasting health impacts." Official reports said of oil were spilled, but critics of the oil company and the government say that the spill was much larger and warned of health risks posed both by the spill and by the chemicals being used to disperse the oil. A higher estimate of the oil spill has been performed by Somporn Chuai-aree of Prince Songkhla University: "as low as or as high as ". This estimate