Deepwater Horizon Oil Spill

The Deepwater Horizon Oil Spill was, to date, largest oil spill in the history of the USA and second largest in the world. It was caused by an explosion on the Deepwater Horizon oil platform about 50 miles southeast of the Mississippi River delta on April 20, 2010. Most of the 126 workers on the platform were safely evacuated, and a search and rescue operation began for 11 missing workers. The Deepwater Horizon oil platform sank in about 5,000 feet (1,500 m) of water on April 22, 2010. On April 23, 2010, the U.S. Coast Guard suspended the search for missing workers who were all presumed dead. After a series of failed efforts to plug the open hole, BP said on July 15, 2010 that it had capped the well, stopping the flow of oil into the Gulf of Mexico for the first time in 86 days.

The sinking of the platform caused crude oil to gush out of the riser, a 5,000-foot pipe, that connects the well at the ocean floor to the drilling platform on the surface. Attempts to shut down the flow, first estimated at about 1,000 barrels of oil a day, failed when a safety device called a blowout preventer could not be activated. On April 28, 2010, government officials said there were three leaks and the well was spilling over 5,000 barrels of oil a day, over 200,000 gallons, nearly a mile below the sea surface. The exact spill flow rate is uncertain and is part of an ongoing debate. Some independent estimates made in the initial days of the accident put the spill rate as in the range of 20,000 to 100,000 barrels per day.