The Deepwater Horizon oil spill was an industrial disaster that began on 20 April 2010, in the Gulf of Mexico on the BP-operated Macondo Prospect,[6][7][8][9] considered to be the largest marine oil spill in the history of the petroleum industry and estimated to be 8 to 31 percent larger in volume than the previous largest, the Ixtoc I oil spill, also in the Gulf of Mexico. The U.S. federal government estimated the total discharge at 4.9 Mbbl (210 million US gal; 780,000 m3).[3] After several failed efforts to contain the flow, the well was declared sealed on 19 September 2010.[10] Reports in early 2018 indicated that the well site was still leaking.[11][12] The Deepwater Horizon oil spill is regarded as one of the largest environmental disasters in American history.