An explosion on April 20, 2010, aboard the Deepwater Horizon, a drilling rig working on a well for the oil company BP one mile below the surface of the Gulf of Mexico, led to the largest accidental oil spill in history.
After a series of failed efforts to plug a gushing leak, BP said in July 2010 that it had capped what it had named the Macondo well, marking the first time in 86 days that oil was not gushing into the gulf. Nearly five months after it blew out of control, the federal government finally declared the well dead in September, after pressure tests confirmed that cement pumped into the base of the well through a relief well formed an effective, and final, seal. The Macondo well and the two relief wells were to be abandoned, following standard industry practices.
Government scientists estimated that nearly five million barrels of oil flowed from BP's well, an amount outstripping the estimated 3.3 million barrels spilled into the Bay of Campeche by the Mexican rig Ixtoc I in 1979.
The oil spilled from the BP well first made landfall in Louisiana. But in June, tar balls and oil mousse had reached the shores of Mississippi, Alabama and Florida. Shortly thereafter, it spread on shore, smearing tourist beaches, washing onto the shorelines of sleepy coastal communities and oozing into marshy bays that fishermen have worked for generations.
By August, the slick appeared to be dissolving far more rapidly than anticipated. The long term damage caused by the spill, however, is still uncertain, in part because large amounts of oil spread underwater rather than surfacing. A new study published in the journal Science in late August confirmed the existence of a huge plume of dispersed oil deep in the Gulf of Mexico and suggested that it had not broken down, raising the possibility that it might pose a threat to wildlife for months or even years.
In September 2010, two independent researchers at Columbia University announced that the federal government, after several missteps, had accurately estimated the amount of oil spilled at nearly 172 million gallons; 185 million gallons, a statistical match when the margins of error are figured in, had actually leaked from the broken well, they said.
By November 2010, the emergency program in the Gulf had ended and the settlement phase began.
A presidential panel named to study the accident called it a preventable one, caused by a series of failures and blunders by the companies involved in drilling the well and the government regulators assigned to police them. In a chapter of its final findings released in early 2011, the panel found that BP, Transocean, Halliburton, and several subcontractors working for them took a series of hazardous and time-saving steps without adequate consideration of the risks involved.
Many other consequences will likely ripple out from the spill for a long time to come: investigations by the Justice Department and Congress into the cause of the spill, new regulations imposing tougher review for deepwater drilling, new leadership for BP as the oil giant struggles to repair a shattered reputation. In December 2010, the Department of Justice filed a civil lawsuit in New Orleans against BP and eight other companies over the Gulf of Mexico oil spill. Although the complaint does not specify the damages that the administration is seeking, the fines and penalties under the laws that are cited in the complaint could reach into the tens of billions of dollars.
Hundreds of thousands of people and businesses have filed for emergency payments from the $20 billion BP fund administered by Kenneth R. Feinberg. More than $2.2 billion has been paid so far in emergency money to those affected by the spill. Mr. Feinberg announced the rules for those settlements in November 2010 after consulting with lawyers, state attorneys general, the Department of Justice and BP.
On Feb. 2, 2011, a report commissioned by Mr. Feinberg predicted that the Gulf of Mexico should recover from the environmental damage caused by the enormous BP oil spill faster than many people expected. The prediction, central to Mr. Feinberg's plan for paying claimants, is certain to be controversial among those who believe the damage will be longer-lasting and therefore should result in higher payouts for the spill’s victims.
On the same day, BP said it planned to sell half of its refining capacity in the United States while expanding in faster-growing economies, and that it would resume paying a dividend for the first time since the explosion.