On April 20, 2010, an explosion occurred at the Deepwater Horizon oil rig, sinking the rig, killing 11 workers, and injuring 17 others. As a result of the explosion at the incomplete well, oil began to gush into the ocean. The exact rate of the spill has been difficult to pin down, reported as anywhere from 8,000 to 60,000 gallons per day.
The spill went uncontained for 87 days, as BP made several attempts using four different methods to cap the well. BP was finally successful on July 15, using a “top hat” containment dome that was specially engineered to prevent ice from clogging the tube to the surface, which allowed all the oil spilled each day to be salvaged by ships. Later, two relief wells were installed to mitigate pressure within the dome, and by September 19, the spill was permanently cemented closed.
By December, a federal lawsuit had been filed against BP, holding the company liable for the costs of cleanup and damages. The case was settled in November 2012 when BP agreed to pay $4.5 billion in reparations, as well as plead guilty to several felony counts. A separate class action case was settled in August 2012, creating the Medical Benefits Settlement for certain people whose health was harmed by the spill.
As of June 2013, BP has declared cleanup efforts finished in most affected states. However, tar balls are still often reported on beaches and the Coast Guard continues to lead residual cleanup. The full, long-term effects on the environment, its wildlife, and human inhabitants remain to be seen.