2010 Gulf of Mexico Oil Spill Timeline

Updated September 9, 2022 | Infoplease Staff

by Dana J. Quigley and Catherine McNiff

Source: U.S. Coast Guard

April | May | June | July | August | September | November | December | February 2011 | March 2011 | November 2012

The following timeline includes the major developments related to the 2010 Gulf of Mexico oil spill. The circumstances surrounding the spill, the amount of oil spilled, and the attendant environmental damage are also given.


Tuesday, April 20
Located about 50 miles southeast of the Louisiana coast, British Petroleum's (BP) Deepwater Horizon oil rig explodes around 11 p.m. EST. As many as 15 crew members are reported missing; 98 workers escape without serious injury.
Thursday, April 22
The search continues for 11 confirmed missing workers. Deepwater Horizon continues to burn. A 30-mile-long plume of smoke emanates from the rig. Effects of the explosion may have been worse if the rig had been in production rather than in exploration mode. The rig later sinks into the ocean.
Sunday, April 25
The Coast Guard allows the use of remote underwater robots to activate a blowout preventer to stop the leak.
Monday, April 26
Rescue efforts for missing crew members are suspended. Underwater robots discover two leaks that are dumping about 1,000 barrels of oil per day into the ocean. Speculation about the environmental, financial, and personal impact of the oil spill (or more accurately described, oil leak) raises wide concern.
Wednesday, April 28
Experts are stumped about how to stop the leaks and effectively clean up the oil already in the ocean. The U.S. Coast Guard suggests a solution to set the oil slick on fire; a contained area is set on fire later in the day. Experts revised their leak rates from 1,000 barrels of oil per day to 5,000. It is confirmed that the oil slick has reached the Mississippi Delta.
Thursday, April 29
President Obama pledges all available resources to contain the spill. He also says that BP will be held responsible for the cleanup.
Friday, April 30
The Obama administration states that it will not authorize any new offshore drilling until the cause of the rig explosion is fully understood and measures to prevent another such disaster are put in place.
BP CEO Tony Hayward says that BP takes full responsibility for the spill and will pay for the cleanup and all legitimate claims.


Saturday, May 1
The leak rate is revised further to 25,000 barrels per day from the previous estimate of 5,000.
Sunday, May 2
President Obama visits the Gulf Coast to see the results of the cleanup. BP begins to dig a relief well alongside the failed well, but the project will take several weeks—perhaps months—to complete. A 10-day ban on fishing in affected areas is put into place.
Monday, May 3
The oil slick appears to be drifting toward the Alabama and Florida coasts. BP tries to stop one of the leaks by installing a shutoff valve.
Tuesday, May 4
News reports reveal that BP had a handful of options to prevent the disaster but did not implement all of them. Aside from a $500,000 acoustic cut-off switch, a deep-water valve could have been placed under the sea floor as another measure to seal any potential leaks. The relaxing of U.S. regulation in recent years allowed BP save money by not employing such preventative measures.
Wednesday, May 5
BP succeeds in plugging one of three leaks in the oil line. It plans to lower a 100-ton containment dome over one of the remaining leaks to siphon the oil. Though the leak is plugged, it fails to affect the amount of oil spilling out.
Friday, May 7
The containment dome fails. Later, it is speculated that BP may have been able to seal the leak rather than trying to siphon the oil from the leak into a nearby tank. The dome failed due to frozen materials clogging the device. The Fishing ban is extended and expanded.
Sunday, May 9
BP reveals a "junk shot" plan that includes plugging the leak by pumping golf balls and shredded tires into the oil well.
Tuesday, May 11—Wednesday, May 12
Executives from BP, Transocean, which owns the oil rig, and Halliburton, the company contracted to cement to well, appear at congressional hearings in Washington. Each executive blames the other companies for the disaster and concedes that many errors led to the explosion.
Friday, May 14
BP attempts to intubate the bigger of the two oil leaks with a smaller pipe to siphon the oil. President Obama lambasts the involved companies for trying to dodge blame for the disaster.
Sunday, May 16
The intubation of the leak succeeds, but it fails to capture a significant amount of oil.
Tuesday, May 18
The no-fishing zone is extended to 19% of waters in the Gulf of Louisiana.
Monday, May 24
BP further delays a method to clog the well and thus prevent further leaks. The method is called "top kill."
Wednesday, May 26
"Top kill" is attempted and seems to succeed—a mixture of cement and mud is pumped into the leak 5,000 feet below the surface in order to clog the well.
Friday, May 28
President Obama returns to the Louisiana Gulf for his second visit. Tony Hayward says that the disaster has cost BP $930 million.
Saturday, May 29
40 days into the spill, the "top kill" method is abandoned because the mixture cannot overpower the pressure of the oil spilling from the leak.


Tuesday, June 1
Outrage ensues when Tony Hayward says, "I'd like my life back." BP shares plunge about 17%, losing $23 billion in market value; BP stock lost about $67 billion over the six weeks since the explosion. The U.S. Justice Department launches a criminal investigation into the initial explosion and the ensuing spill. Fishing restrictions increase to 37% of federal waters in the Gulf.
Thursday, June 3
Technicians cut a riser pipe nearly one-mile under the surface and plan to then dome the leak and siphon the oil to a tank on the surface. As a result, the rate of flow increased by 20% beause the oil has less distance to travel to leak.
Friday, June 4
President Obama cancels his trip to Australia, Indonesia, and Guam to make his third trip to the Gulf Coast. He voices his outrage at BP for spending millions of dollars on television advertisements.
Saturday, June 12
President Obama speaks with British Prime Minister David Cameron about BP oil spill. The U.S. Coast Guard orders BP engineers to increase the rate of containment of the spewing oil; the consequences for failing to do so are not outlined, however.
Sunday, June 13
BP officials state that the containment cap captured 15,000 barrels of oil on the previous day, bringing the total number of barrels captured by the device to 119,000.
Monday, June 14
President Obama visits the Gulf for the fourth time in eight weeks. Congress and the Obama administration demand that BP halt paying dividends to its shareholders in order to ensure that the company will have money to pay for damages. BP says it will be able to siphon 40,000 to 53,000 barrels a day by the end of June.
Tuesday, June 15
Oil executives are summoned to Congress to testify about the safety of offshore drilling and share their response plans for another such disaster. Leak estimates are increased to 60,000 barrels per day; this means 2.5 million barrels a day are spilling into the Gulf. At this rate, the amount of the Exxon Valdez spill is reproduced every four days. That night, President Obama delivers a speech about the oil spill from the Oval Office. The speech, his first from the Oval Office, is watched by 32 million viewers.
Wednesday, June 16
President Obama meets with top executives and lawyers of BP at the White House. He later announces that BP agreed to create a $20 billion fund to pay claims and damages. The fund will be run by Kenneth R. Feinberg, who oversaw the compensation for victims of Sept. 11.
Thursday, June 17
Tony Hayward testifies before Congress. The U.S. Coast Guard reports that containment devices should be able to capture 53,000 barrels per day by the end of June. In the future, the collection of 60,000 to 80,000 barrels a day may take place with the successful implementation of a new, multi-hose well cap. BP recovers 25,290 barrels of oil, the most it has recovered in a single day. Rep. Joe Barton (R-Texas) apologizes to BP for being forced by the Obama administration to create a $20 billion fund, calling it a "shakedown." Under pressure, he later apologizes for his apology.
Friday, June 18
Tony Hayward steps away from BP's response efforts and passes the responsibilities to Robert Dudley, the managing director of BP. Hayward still remains the CEO of BP. The Center for Biological Diversity files a lawsuit against BP, seeking monetary penalties for the disaster under the Clean Water Act. The Center calculates that BP's liability will be around $19 billion, assuming the spill continues into August.
Saturday, June 19
Anadarko Petroleum, which owns a quarter of the well, denies any responsibility for the disaster. CEO Jim Hackett blames BP for "gross negligence."
Sunday, June 20
Photos of Hayward with his son as a yacht race make their way into the US media and cause frenzy throughout the country.
Tuesday, June 22
American Bob Dudley assumes control of the spill from Hayward at a major oil industry conference; Hayward is not present. Chief of staff Steve Westwell delivers a speech on Hayward's behalf and is disrupted as two Greenpeace protesters assume the stage.
Wednesday, June 23
An underwater robot bumps into the wellhead cap which results in oil gushing unhindered for several hours.
Friday, June 25
BP announces the cost of containing and cleaning the oil spill reaches $2.35 billion.
Monday, June 28
The Guardian, a widely circulated British newspaper, publishes a protest letter signed by 171 critics, writers, and artists about BP's financial ties to the Tate Britain gallery. Later on, activists dump molasses over the gallery's steps during a party intended to celebrate ten years of BP sponsorship.
Wednesday, June 30
Tall waves, created as a result of Hurricane Alex, halt clean-up efforts.


Monday, July 5
BP announces the cost of containing and cleaning the oil spill reaches $3.12 billion. BP asks its partners, Misui Oil Exploration and Andarko Petroleum, to contribute $400 million to the rising bill. Mitsui and Andarko own 10% and 25%, respectively.
Wednesday, July 7
An investigation by the Associated Press reveals that there are more than 27,000 abandoned oil wells in the Gulf of Mexico; more than 600 belonged to BP. State officials believe that many of the abandoned wells are badly sealed and pose a high risk of pollution.
Friday, July 9
A US appeals court rejects the government's plan to restore the off-shore drilling moratorium. 33 exploratory wells were suspended from drilling during the moratorium weeks earlier.
Sunday, July 11
Underwater robots remove a defective cap from the well and begin the process of installing a new containment system. During this time, oil gushes undisturbed from well.
Monday, July 12
BP announces the cost of containing and cleaning the oil spill reaches $3.5 billion. This number includes $165 million paid dispersed to 52,000 claims paid out of the total of 105,000 claims submitted so far.
Tuesday, July 13
BP successfully installs a new containment cap on the well. Testing will determine if the tighter-fitting cap will prevent oil from spewing from the well.
Thursday, July 15
For the first time in 87 days, oil stops leaking from the well. Engineers continue to conduct tests to ascertain if the cap will succeed in permanently stopping the oil flow.
Tuesday, July 20
The U.S. Coast Guard gives BP engineers 24 hours to determine the stability of the containment cap. UK Prime Minister David Cameron meets with President Obama in Washington to discuss the oil spill.
Wednesday, July 21
David Cameron tells members of Congress that BP is not solely responsible for the disaster and that the other parties should share in the cost of damages.
Friday, July 23
Tropical storm Bonnie temporarily halts relief work on the well. It is revealed that the alarms that should have sounded hours before the Deepwater Horizon explosion were turned off to prevent waking sleeping workers.
Sunday, July 25
Crews resume work on the relief well; they must complete the well before peak hurricane season.
Monday, July 26
BP announces that chief executive Tony Hayward will be replaced by American Bob Dudley, who is currently overseeing cleanup efforts.
Tuesday, July 27
BP plans to use $10 billion in tax credits to pay for the cleanup; some of the credits have been paid for by U.S. and UK taxpayers. Greenpeace activists in London force the closure of 46 BP stations by removing safety switches from gas pumps.
Thursday, July 29
Shell announces that it lost $56 million due to the moratorium on offshore drilling and may pursue compensation from BP for damages.


Monday, August 2
BP gears up to try a "static kill" to finally stop the flow of oil. Like the other "kill" methods, this involves pumping mud and cement into the damaged well to prevent more oil from leaking into the ocean.
Thursday, August 5
Workers complete the static kill with the pumping of tons of mud followed by cement into the drill pipe and oil reservoir.
Sunday, August 8
BP announces that the static kill is a success and will prevent further leakage until the relief well can be connected and a final kill achieved.
Monday, August 9
The first of two relief wells, which was started on May 2, is within 30–40 ft of the damaged well.
BP and the Justice Department announce a $20 billion fund for oil spill victims into which BP has made a $3 billion deposit.
Friday, August 13
The government announces plans to continue drilling the relief well even though tests reveal that the static kill was successful.


Tuesday, September 8
BP releases a 193–page internal report investigating the causes of the spill. The report spreads the blame to include not only BP but also Transocean (owner of rig) and Halliburton (performed cementing jobs).
Sunday, September 19
After a successful pressure test on the cement seal delivered by a relief well, the Macondo 252 well is declared dead. The oil rig had pumped an estimated 205 million gallons of oil into the Gulf of Mexico until flow was stopped July 15. Now that a total kill has been achieved, the rig and relief wells will be abandoned. Cleanup efforts in the Gulf continue.
Thursday, September 23
Timothy Crone and Maya Tolstoy, researchers at Columbia University, release a peer-reviewed paper that- taking into account margins of error-confirms the government's estimates of the amount of oil spilled. Using a new technique called optical plume velocimetry, the scientists estimate the amount of oil spilled into the Gulf of Mexico at 185 million gallons (4.4 million barrels). This number does not include the 804,877 barrels that BP recovered from the site.


Tuesday, November 23
This day marks the deadline for applicants seeking lump sum payments from the $20 billion BP fund. Victims who receive one-time payments agree to forgo any rights to sue any of the major defendants. Those who decide to sue potentially face years of litigation.

December 2011

Wednesday, December 15
The Department of Justice files a civil lawsuit in New Orleans against BP and eight other companies seeking unspecified damages.

February 2011

Wednesday, February 2
BP announces plans to sell half of its refining capacity in the U.S., expand its interests in growing economies, and resume dividend payments.

March 2011

Friday, March 11
The National Commission on the Deepwater Horizon Oil Spill and Offshore Drilling (an independent entity created by President Obama on May 22, 2010, to investigate the disaster) ceases operations. The investigation concluded that the oil well blowout was preventable and "can be traced to a series of identifiable mistakes made by BP, Halliburton, and Transocean that reveal such systematic failures in risk management that they place in doubt the safety culture of the entire industry."

November 2012

Thursday, November 15
The British oil company, BP, agrees to a guilty plea on 14 criminal charges involving the rig explosion in 2010 that caused a giant oil spill in the Gulf of Mexico and killed 11 people. BP also agrees to pay $4.5 billion in fines and penalties. In addition, the company's safety practices and ethics will also be monitored by the U.S. government for the next four years. At a news conference to announced the settlement, Attorney General Eric H. Holder, Jr. says, "This is unprecedented, both with regard to the amounts of money, the fact that a company has been criminally charged and that individuals have been charged as well."

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