The Deepwater Horizon oil spill was an environmental disaster that began on April 20, 2010, off the coast of the United States in the Gulf of Mexico, on the BP-operated Macondo Prospect. It is considered the largest marine oil spill in the history of the petroleum industry. Scientists estimate it was 8 to 31 percent larger in volume than the previous largest spill, the Ixtoc I oil spill, which also occurred in the Gulf of Mexico. The spill happened after a blowout and explosion on the Deepwater Horizon oil platform. The United States federal government estimated that the total amount of oil released was 4.9 million barrels (210,000,000 U.S. gallons; 780,000 cubic meters). After several failed attempts to stop the flow, the well was declared sealed on September 19, 2010. Reports in early 2012 showed that the well site was still leaking. The Deepwater Horizon oil spill is regarded as one of the largest environmental disasters in world history.

A large cleanup effort began to protect beaches, wetlands, and estuaries from the spreading oil. Methods used included skimmer ships, floating booms, controlled burns, and 1,840,000 U.S. gallons (7,000 cubic meters) of oil dispersant. Because the spill lasted for months and cleanup efforts had harmful effects, extensive damage to marine and wildlife habitats, as well as fishing and tourism industries, was reported. In Louisiana, oil cleanup crews worked four days a week on 55 miles (89 kilometers) of shoreline throughout 2013. Over 4,900,000 pounds (2,200 tons) of oily material was removed from the beaches in 2013, more than double the amount collected in 2012. Oil was found as far away as the waters off the Florida panhandle and Tampa Bay, where scientists said the oil and dispersant mixture became embedded in the sand. In April 2013, it was reported that dolphins and other marine life continued to die in record numbers, with infant dolphins dying at six times the normal rate. A study from 2014 found that tuna and amberjack exposed to oil from the spill developed heart and other organ deformities that would likely be fatal or shorten their lives. Another study suggested that heart damage might have been widespread in animals exposed to the spill.

Many investigations looked into the causes of the explosion and the large spill. A United States government report published in September 2011 pointed to faulty cement on the well, mostly blaming BP, but also the rig operator Transocean and the contractor Halliburton. Earlier in 2011, a White House commission also blamed BP and its partners for making cost-cutting decisions and having an unsafe system. It concluded that the spill resulted from "systemic" root causes and warned that without major changes in industry practices and government policies, similar events could happen again.

In November 2012, BP and the United States Department of Justice settled federal criminal charges. BP pleaded guilty to 11 counts of manslaughter, two misdemeanors, and a felony count of lying to the United States Congress. BP agreed to four years of government monitoring of its safety practices and ethics. The Environmental Protection Agency announced that BP would be temporarily banned from new contracts with the United States government. BP and the Department of Justice agreed to a record $4.525 billion in fines and other payments. In September 2014, a United States District Court judge ruled that BP was primarily responsible for the oil spill because of its gross negligence and reckless conduct. In April 2016, BP agreed to pay $20.8 billion in fines, the largest environmental damage settlement in United States history. As of 2018, cleanup costs, charges, and penalties had cost the company more than $65 billion.

Background

Deepwater Horizon was a large floating drilling platform that could move and stay in place using special technology. It was built by a company in South Korea called Hyundai Heavy Industries and owned by a company named Transocean. The rig operated under the flag of the Marshall Islands and was rented to BP from March 2008 to September 2013. It was drilling a well that was 18,360 feet (5,600 meters) below the ocean surface in water that was about 5,100 feet (1,600 meters) deep. The well was located in the Macondo Prospect, which is part of Mississippi Canyon Block 253 (MC253) in the Gulf of Mexico, within the United States' exclusive economic zone. This area is about 41 miles (66 kilometers) from the coast of Louisiana. BP was the main company managing the Macondo Prospect and owned 65% of it. Anadarko Petroleum owned 25%, and MOEX Offshore 2007, a company owned by Mitsui, owned 10%.

On April 20, 2010, at about 7:45 pm Central Daylight Time, high-pressure methane gas from the well entered the pipe leading to the rig. The gas ignited and exploded, causing a fire that spread across the platform. Eleven workers were missing after the explosion and were not found during a three-day search by the U.S. Coast Guard. It is believed they died in the explosion or its effects. Ninety-four crew members were rescued by lifeboats or helicopters, and 17 of them received treatment for injuries. The Deepwater Horizon sank on the morning of April 22, 2010.

Volume and extent of oil spill

The oil leak was found on the afternoon of April 22, 2010, when a large oil slick began spreading at the site of the former oil rig. The oil flowed for 87 days. BP first estimated the oil was leaking at a rate of 1,000 to 5,000 barrels per day (160 to 790 cubic meters per day). A group of experts called the Flow Rate Technical Group (FRTG) calculated the initial flow rate was 62,000 barrels per day (9,900 cubic meters per day). The total amount of oil that leaked was estimated to be about 4.9 million barrels (210,000,000 U.S. gallons; 780,000 cubic meters), with a possible 10% error in the estimate. This included oil that was collected, making it the largest accidental oil spill in the world. BP disagreed with the higher estimate, claiming the government overestimated the amount of oil spilled. Internal emails from 2013 showed a BP employee had numbers matching the FRTG’s estimates and shared them with supervisors, but BP continued using its lower number. BP argued that government estimates did not account for over 810,000 barrels (34 million U.S. gallons; 129,000 cubic meters) of oil that was collected or burned before reaching the Gulf of Mexico.

Satellite images showed the spill directly affected 70,000 square miles (180,000 square kilometers) of ocean, an area about the size of Oklahoma. By early June 2010, oil had reached 125 miles (201 kilometers) of Louisiana’s coast and the coasts of Mississippi, Florida, and Alabama. Oil sludge appeared in the Intracoastal Waterway and on Pensacola Beach and the Gulf Islands National Seashore. In late June, oil reached Gulf Park Estates, its first appearance in Mississippi. In July, tarballs (small, sticky pieces of oil) reached Grand Isle and the shores of Lake Pontchartrain. In September, a new wave of oil coated 16 miles (26 kilometers) of Louisiana coastline and marshes west of the Mississippi River in Plaquemines Parish. In October, weathered oil reached Texas. By July 2011, about 491 miles (790 kilometers) of coastline in Louisiana, Mississippi, Alabama, and Florida were contaminated by oil, with a total of 1,074 miles (1,728 kilometers) affected since the spill began. By December 2012, 339 miles (546 kilometers) of coastline still needed evaluation or cleanup. The reported 3.19 million barrels of spilled oil was not the only effect of the disaster. A report noted the release of thousands of tons of hydrocarbon gases (HC) into the atmosphere.

Scientists were concerned about underwater plumes of dissolved oil. Researchers said deep plumes of oil and gas would likely stay in the northern Gulf of Mexico, and the impact on oxygen levels in the water would be delayed and last a long time. Two weeks after the well was capped on July 15, 2010, surface oil seemed to disappear, but an unknown amount of oil remained below the surface. Estimates of the remaining oil ranged from a 2010 NOAA report stating about half of the oil stayed underwater to other estimates suggesting up to 75% remained. That means over 100 billion U.S. gallons (380 million liters) (2.4 million barrels) of oil stayed in the Gulf. By January 2011, tar balls, oil sheen trails, and oil-covered wetlands and coastal sands were still visible. Subsurface oil remained offshore and in fine silts. In April 2012, oil was still found along as much as 200 miles (320 kilometers) of Louisiana coastline, and tar balls continued washing up on barrier islands. In 2013, scientists said as much as one-third of the oil may have mixed with deep ocean sediments, risking harm to ecosystems and fisheries.

In 2013, over 4,600,000 pounds (2,100 tons) of "oiled material" was removed from the Louisiana coast. Although only small amounts of oil continued to wash up in 2013, tar balls were still reported almost daily on Alabama and Florida Panhandle beaches. Cleanup patrols were no longer routine, but cleanup work continued as needed in response to public reports.

People first thought the oil did not reach as far as Tampa Bay, Florida. However, a 2013 study found a plume of dispersant-treated oil had reached a shelf 80 miles (130 kilometers) off the Tampa Bay region. Researchers said there was "some evidence" the oil may have caused injuries in fish caught in that area.

Efforts to stem the flow of oil

BP first tried to close the blowout preventer valves on the wellhead using remotely operated underwater vehicles, but this did not work. Next, BP placed a 125-tonne (280,000 lb) containment dome over the largest leak and used pipes to direct the oil to a storage vessel. This method had worked in shallower water, but it failed here because gas mixed with cold water to form methane hydrate crystals, which blocked the dome’s opening. Pumping heavy drilling fluids into the blowout preventer to control the oil flow before sealing it permanently with cement ("top kill") also failed.

BP then inserted a riser insertion tube into the pipe and used a stopper-like washer to plug the end of the riser, redirecting the flow into the tube. Collected gas was burned, and oil was stored on the drillship Discoverer Enterprise. Before removing the tube, it collected 924,000 US gallons (22,000 bbl; 3,500 m³) of oil. On 3 June 2010, BP removed the damaged drilling riser from the blowout preventer and covered the pipe with a cap connected to another riser. On 16 June, a second containment system directly connected to the blowout preventer began carrying oil and gas to service vessels, where it was burned in a clean-burning system. The U.S. government estimated that the cap and other equipment captured less than half of the leaking oil. On 10 July, the containment cap was replaced with a better-fitting cap ("Top Hat Number 10"). Later, mud and cement were pumped into the well to reduce pressure, but this also failed. A final device was created to attach a larger-diameter chamber to the blowout preventer, with a flange that bolted to the top and a manual valve to close the flow. On 15 July, the device was secured, and valves were closed under increasing pressure to complete temporary measures.

Transocean’s Development Driller III began drilling a first relief well on 2 May 2010. GSF Development Driller II started drilling a second relief well on 16 May 2010. On 3 August 2010, test oil and drilling mud were pumped slowly into the wellhead at about 2 bbl (320 L) per minute for eight hours, after which the well was declared "in a static condition." On 4 August 2010, BP began pumping cement from the top to permanently seal the flow channel.

On 3 September 2010, the 300-ton failed blowout preventer was removed and replaced. On 16 September 2010, the relief well reached its target, and cement was pumped to seal the well. On 19 September 2010, National Incident Commander Thad Allen declared the well "effectively dead," stating it posed no further threat to the Gulf.

In May 2010, BP admitted that during the "top kill" effort, they discovered broken equipment in the subsurface.

Oil slicks were reported in March and August 2011, March and October 2012, and January 2013. Scientists tested the oil and confirmed it matched the Macondo well’s oil.

The U.S. Coast Guard (USCG) initially said the oil was too dispersed to recover and posed no threat to the coastline. Later, the USCG warned BP and Transocean they might be held financially responsible for cleaning up the new oil. USGS director Marcia McNutt stated the riser pipe could hold at most 1,000 bbl (160 m³) because it is open on both ends, making it unlikely to hold the observed amount of oil.

In October 2012, BP reported finding and plugging leaking oil from the failed containment dome, now abandoned about 1,500 ft (460 m) from the main well. In December 2012, the USCG conducted a subsea survey and found no oil coming from the wells or wreckage, though a white, milky substance was observed seeping from the wreckage. BP and the USCG stated this substance is "not oil and it's not harmful."

In January 2013, BP said it was investigating possible sources of the oil sheen. Chemical data suggested the substance might be residual oil leaking from the wreckage. If confirmed, the sheen would eventually disappear. Another possibility is that it is formation oil escaping from the subsurface, using the Macondo well casing as a flow path, possibly through a natural fault, and reaching the surface far from the wellhead. If this proves true, it could mean an indefinite oil release. The oil slick was similar in size to naturally occurring oil seeps and was not large enough to immediately threaten wildlife.

Containment, collection and use of dispersants

The main methods used to deal with the oil spill were containment, dispersal, and removal. In summer 2010, about 47,000 people and 7,000 boats helped with the cleanup. By October 3, 2012, the federal government had spent $850 million on the response, mostly paid back by BP. As of January 2013, 935 workers were still involved. By that time, BP had spent over $14 billion on cleanup efforts.

Scientists estimated that about 4.9 million barrels (780,000 cubic meters) of oil was released from the well, with 4.1 million barrels (650,000 cubic meters) entering the Gulf. A report by the Department of the Interior and NOAA stated that "75% of the oil has been cleaned up by humans or natural processes." However, only 25% of the oil was collected or removed, while 75% remained in the environment. In 2012, Markus Huettel, a scientist who studies ocean life, said that at least 60% of the oil from BP was still unaccounted for.

In May 2010, a local person created a network to help volunteers clean beaches. Boat captains were asked to use their boats to help stop the oil from spreading. These captains had to register their ships with a program called Vessels of Opportunity, but only about one-third of the registered boats actually helped. Many people were upset with BP’s slow response, leading to the creation of The Florida Key Environmental Coalition, which tried to take control of cleanup efforts.

Containment booms, which are barriers used to trap oil, stretched over 4,200,000 feet (1,300 kilometers). These were used to protect marshes, mangroves, and other sensitive areas. Booms were only effective in calm, slow-moving water. A total of 13,300,000 feet (4,100 kilometers) of booms were used, including one-time-use sorbent booms. However, booms were criticized for allowing oil to escape or washing up on shore.

A plan to build barrier islands in Louisiana was criticized for being expensive and not working well. Some people said the plan was made for political reasons without enough scientific support. The EPA worried that booms could harm wildlife.

A group called Matter of Trust encouraged hair salons, dog groomers, and sheep farmers to donate hair, fur, and wool to help contain oil near affected areas. This idea was used during the Exxon Valdez disaster.

The spill involved a large amount of Corexit, a type of oil dispersant. About 1.84 × 10^6 US gallons (7,000 cubic meters) of dispersants were used, with 771,000 US gallons (2,920 cubic meters) released directly at the well. Subsea injection, a new method, was used for the first time. Over 400 flights were made to spread the dispersants. While dispersants were called the most effective tool for reducing shoreline damage, their use is still being studied.

A 2011 study showed that Corexit could contain harmful chemicals, including cancer-causing agents and toxins that harm sea life. Scientists were worried that dispersants made the oil more dangerous for sea turtles and bluefin tuna. Some experts said Corexit was still used after the oil leak was capped, even though BP and officials claimed it stopped.

A NALCO manual said Corexit 9527 can irritate the eyes and skin and may harm red blood cells, kidneys, or the liver. It warned to avoid contact with skin, eyes, or clothing and to wear protective gear. Similar warnings were given for Corexit 9500. However, cleanup workers were not given protective gear or the manual, according to reports.

Corexit EC9500A and Corexit EC9527A were the main types used. These were not the least toxic or most effective dispersants approved by the EPA, but BP said they were the only ones available when the spill happened. The EPA gave BP 24 hours to choose less toxic alternatives or explain why none were suitable. BP said no alternatives met the criteria, and the EPA later ordered a reduction in dispersant use by 75%. BP reduced Corexit use by about 9% per day. The EPA later said dispersants caused less harm than the oil itself and helped break it down faster. However, some scientists and EPA experts still raised concerns.

Injecting Corexit underwater may have created oil plumes deep below the surface. One plume was 22 miles long, over a mile wide, and 650 feet deep. Scientists were worried about how slowly the oil broke down in cold, deep water.

A 2012 study found that Corexit made the oil 52 times more toxic to ecosystems. Scientists said mixing oil with dispersants worsened the environmental impact of the spill.

The three main methods to remove oil from water were burning, filtering it offshore, and collecting it for later processing. The USCG said 33,000,000 US gallons (120,000 cubic meters) of oil-contaminated water was recovered, including 5,000,

Access restrictions

On May 18, 2010, BP was named the lead "Responsible Party" under the Oil Pollution Act of 1990. This role gave BP the responsibility to manage and coordinate the response efforts.

The first video images were released on May 12. Later, members of Congress shared additional video images with the public after BP provided them access.

During the spill response, the Coast Guard requested the Federal Aviation Administration (FAA) to create a temporary flight restriction zone covering 900 square miles (2,300 square kilometers) over the affected area. This rule was put in place to keep civilian aircraft from interfering with response planes. Only certain flights were allowed, including those approved by air traffic control, flights supporting offshore oil operations, and flights by federal, state, local, or military officials involved in the response. Exceptions to these rules were made based on safety, weather, and traffic conditions. Flights below 1,000 meters (3,300 feet) were not allowed, except for planes spreading chemicals to clean the oil or planes taking off or landing. Despite these restrictions, between 800 and 1,000 flights occurred daily in the area.

Local and federal officials, citing BP’s authority, blocked journalists from accessing the spill site by air, on boats, or on land. In some cases, photographers were only allowed to enter with BP employees on BP-owned boats or planes. For example, the U.S. Coast Guard stopped a boat operated by Jean-Michel Cousteau and allowed it to continue only after confirming no journalists were on board. Another instance involved a CBS News team being denied access to oil-covered beaches, with officials stating, "This is BP’s rules, not ours." Some members of Congress criticized these restrictions on media access.

The FAA stated that BP employees or contractors did not make decisions about flights or access, as these decisions were handled by the FAA and Coast Guard. The FAA noted that media access was limited to planes or helicopters hired by the Coast Guard. The Coast Guard and BP said they did not have a policy to restrict journalists. They explained that media representatives had been allowed to join response teams since the beginning, with over 400 journalists embedded on boats and aircraft. They emphasized their goal to share information while ensuring safety.

Cleanup

On April 15, 2014, BP stated that cleanup efforts along the coast were mostly finished. At the same time, the United States Coast Guard continued using physical barriers, such as floating booms, to stop the oil from spreading further. Cleanup workers used skimmer boats to remove most of the oil and sorbents, which absorbed leftover oil like a sponge. Although this method did not remove all the oil, chemicals called dispersants were used to speed up the oil’s breakdown and reduce harm to underwater marine habitats. For the Deepwater Horizon oil spill, cleanup workers used 1,400,000 US gallons (5,300,000 liters; 1,200,000 imperial gallons) of different chemical dispersants to help break down the oil.

The state of Louisiana received money from BP to regularly test fish, shellfish, water, and sand. Early tests showed detectable levels of dioctyl sodium sulfosuccinate, a chemical used during the cleanup. Testing results from 2019, reported by GulfSource.org, found no harmful levels of the pollutants tested.

The Deepwater Horizon spill harmed marine life. Thousands of animals were covered in oil. The U.S. Fish and Wildlife Service, along with the Smithsonian's National Zoological Park, rescued animals to help with the cleanup. However, many animals were found dead.

Consequences

The spill area is home to 8,332 species, including more than 1,270 types of fish, 604 polychaetes, 218 birds, 1,456 mollusks, 1,503 crustaceans, 4 sea turtles, and 29 marine mammals. Between May and June 2010, the water from the spill contained 40 times more polycyclic aromatic hydrocarbons (PAHs) than before the spill. PAHs are often linked to oil spills and include cancer-causing substances and chemicals that can harm humans and marine life. The PAHs were most concentrated near the Louisiana Coast, but levels also increased 2–3 times in areas off Alabama, Mississippi, and Florida. PAHs can directly harm marine species, and microbes that break down oil can reduce oxygen levels in the water. The oil contained about 40% methane by weight, compared to about 5% in typical oil deposits. Methane can harm marine life and create "dead zones" where oxygen is low.

A 2014 study on the effects of the oil spill on bluefin tuna, supported by NOAA, Stanford University, and the Monterey Bay Aquarium and published in the journal Science, found that toxins from oil spills can cause irregular heartbeats, which may lead to heart failure. Researchers called the spill area "one of the most productive ocean ecosystems in the world" and noted that even small amounts of PAHs could harm many species. Another study, published in Proceedings of the National Academy of Sciences in March 2014, found that tuna and amberjack exposed to oil from the spill had heart and organ deformities that could be fatal or shorten their lives. Scientists said these findings likely apply to other large predator fish and possibly to humans, as human and fish heart development share similarities. BP claimed the oil concentrations in the study were rare in the Gulf, but The New York Times reported that this statement contradicted the study’s findings.

The oil dispersant Corexit, usually used on the water’s surface, was released underwater in large amounts to help microbes break it down. This caused oil to mix with water, forming tiny droplets that stayed in the water and on the seafloor. The oil and dispersant mixture entered the food chain through zooplankton. Signs of the mixture were found in the shells of tiny blue crab larvae. A study of insect populations in coastal marshes affected by the spill found significant impacts. Chemicals from the spill were detected in migratory birds as far away as Minnesota. Pelican eggs contained "petroleum compounds and Corexit." Scientists believe dispersants and PAHs caused many fish with deformities, including 50% of shrimp found without eyes or eye sockets. Fish with sores and lesions were first noticed by fishermen in November 2010. Before the spill, about 0.1% of Gulf fish had sores, but later estimates showed 20% or even 50% of fish with sores. In October 2013, Al Jazeera reported that the Gulf ecosystem was "in crisis," citing fewer seafood catches and fish deformities. Researchers with experience in environmental monitoring estimated that over one million coastal birds died directly from the Deepwater Horizon spill.

In July 2010, reports said the spill was already harming marine life in the Gulf. Damage to the ocean floor threatened the Louisiana pancake batfish, which lives only in the spill-affected area. In March 2012, a link was found between the death of a coral community and the spill. NOAA is investigating a cetacean Unusual Mortality Event (UME) that began before the spill, and criminal charges may be filed if the spill is connected. Only about 2% of dead mammal carcasses have been recovered.

In the first dolphin birthing season after the spill, dead baby dolphins washed up along Mississippi and Alabama shores at about 10 times the normal rate. A study by NOAA and BP found that nearly half of the bottlenose dolphins tested in a heavily oiled area in 2011 were in poor health, with 17% unlikely to survive. BP officials said dolphin deaths began before the spill, but by 2013, over 650 dolphins had stranded in the spill area, a four-fold increase from historical averages. The National Wildlife Federation reports that sea turtles, especially endangered Kemp’s ridley sea turtles, have stranded at higher rates. Before the spill, about 100 sea turtles stranded yearly, but the number rose to about 500. Scientists say the high death rates suggest something is seriously wrong with the Gulf ecosystem. In December 2013, a study in Environmental Science & Technology found that half of dolphins captured near Louisiana were seriously ill or dying. BP said the report was not conclusive about the spill’s role.

In 2012, tar balls (sticky oil clumps) continued to wash up along the Gulf coast. By 2013, tar balls were still found on Mississippi and Louisiana coasts, along with oil sheens in marshes and severe erosion of coastal islands caused by tree and grass death from oil exposure. In 2013, a former NASA physicist noted a lack of marine life within 30 to 50 miles of the well.

In 2013, researchers found that oil on the seafloor was not breaking down and observed a phenomenon called a "dirty blizzard," where oil clumped around sediments and fell to the ocean floor like an "underwater rain of oily particles." This could have long-term effects because oil might stay in the food chain for many years.

A 2014 study in Science found that oil broken down by wave action and dispersants was more toxic than fresh oil. A 2015 study in PLOS ONE linked increased dolphin deaths to the Deepwater Horizon spill. In 2016, a study found that 88% of about 360 baby or stillborn dolphins in the spill area had

Reactions

On April 30, President Obama sent the Secretaries of the Department of the Interior and Homeland Security, along with the EPA Administrator and NOAA, to the Gulf Coast to evaluate the disaster. In a speech on June 15, Obama said, "This oil spill is the worst environmental disaster in American history… We will fight this spill with everything we have for as long as it takes. We will make BP pay for the damage their company caused. And we will do whatever is needed to help the Gulf Coast and its people recover from this tragedy." Interior Secretary Ken Salazar said, "Our job is to keep pressure on British Petroleum." Some people believed the Obama administration was too harsh in its criticism, which some BP investors thought was an attempt to avoid blame for how the government handled the crisis. Senator Rand Paul accused President Obama of being anti-business and "un-American."

Public opinion polls in the U.S. were mostly critical of how President Obama and the federal government responded to the disaster, and they were very critical of BP's actions. Across the country, thousands of people joined protests at BP gas stations and other places, which reduced sales at some stations by 10% to 40%. A study about government response to the disaster said that the seriousness of the disruption greatly affects how people view the event, as government groups are not always ready to handle challenges at all levels.

The petroleum industry said that disasters are rare and that this spill was a one-time event, rejecting claims that the industry lost credibility. The American Petroleum Institute (API) said that offshore drilling is important for job creation and economic growth. Leaders from the top five oil companies agreed to work harder to improve safety. API created an offshore safety institute, separate from its lobbying efforts.

The Organization for International Investment, based in Washington D.C., warned that strong criticism could harm the reputation of British companies operating in the U.S. and might lead to U.S. protectionism, which could limit British companies from government contracts, political donations, and lobbying.

In July 2010, President Obama issued an executive order, citing the Deepwater Horizon oil spill, that included recommendations from the Interagency Ocean Policy Task Force and created the National Ocean Council. The council brought together federal groups working on ocean issues to collaborate with a new committee for conservation and resource management. In June 2018, the executive order establishing the National Ocean Council was canceled by President Donald Trump to reduce bureaucracy and support "ocean industries [that] employ millions of Americans."

In the UK, people were angry about how American media used the name "British Petroleum" for the company, which had not been used since BP merged with Amoco in 1998 to form BP Amoco. It was said that the U.S. was unfairly blaming British people, and there were calls for British Prime Minister David Cameron to protect British interests in the U.S. British pension fund managers, who own many BP shares, said that while BP needed to pay for the spill and environmental damage, the harm to the company’s value from President Obama’s criticism was greater than the direct cleanup costs.

At first, BP downplayed the incident. Its CEO, Tony Hayward, said the amount of oil and dispersant was "relatively tiny" compared to the "very big ocean." Later, he faced criticism for saying the spill was a disruption to Gulf Coast residents and adding, "I'd like my life back." BP’s chief operating officer, Doug Suttles, disagreed with reports about an underwater oil plume, saying, "It may depend on how you define a plume… The oil found is in very small amounts." In June, BP launched a public relations campaign and paid to have its website appear first in search results for terms related to the spill. On July 26, 2010, it was announced that CEO Tony Hayward would resign and be replaced by Bob Dudley, an American citizen who previously worked for Amoco.

Hayward’s role in the Deepwater Horizon disaster made him a very controversial figure. In May 2013, he was honored as a "distinguished leader" by the University of Birmingham, but the ceremony was interrupted by jeers and walk-outs from protesters. In July 2013, Hayward was given an honorary degree from Robert Gordon University. This was called a "sick joke" and "a serious mistake" by Friends of the Earth Scotland. The student body president said students would be "very disappointed."

The U.S. government refused help from Canada, Croatia, France, Germany, Ireland, Mexico, the Netherlands, Norway, Romania, South Korea, Spain, Sweden, the United Kingdom, and the United Nations. The U.S. State Department received 70 offers of help from 23 countries, all of which were initially declined. Later, 8 offers were accepted. The U.S. Coast Guard asked several countries for skimming boats and equipment.

Legal aspects and settlements

In the United States, the Deepwater Horizon investigation included several studies and groups, such as reports by:

• the USCG National Incident Commander, Admiral Thad Allen,
• the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling,
• the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE),
• the National Academy of Engineering,
• the National Research Council,
• the Government Accountability Office,
• the National Oil Spill Commission, and
• the Chemical Safety and Hazard Investigation Board.

The Republic of the Marshall Islands Maritime Administrator did a separate investigation into the accident. BP also conducted its own internal investigation.

An investigation into the possible causes of the explosion began on April 22, 2010, by the USCG and the Minerals Management Service. On May 11, the United States government asked the National Academy of Engineering to do an independent technical study. The National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling was created on May 22 to examine the root causes of the disaster and suggest safety and environmental improvements. On June 1, 2010, the United States Attorney General Eric Holder announced an investigation. The United States House Committee on Energy and Commerce held hearings, including those with Tony Hayward and leaders from Anadarko and Mitsui's exploration unit. According to the US Congressional investigation, the rig's blowout preventer, made by Cameron International Corporation, had a hydraulic leak and a failed battery, which caused it to fail.

On September 8, 2010, BP published a 193-page report on its website. The report said that BP, Halliburton, and Transocean shared some responsibility for the accident. It found that on April 20, 2010, managers misunderstood pressure data and approved replacing drilling fluid in the well with seawater, which was not heavy enough to stop gas from leaking into the well and causing the explosion. The report concluded that BP and Transocean, which owned the rig, were partly to blame. Transocean and Halliburton claimed all responsibility was on BP.

On November 9, 2010, a report by the Oil Spill Commission said there was a rush to finish the well and criticized poor management decisions. It noted that safety was not a priority on the rig.

The National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling released its final report on January 5, 2011. The report said BP, Halliburton, and Transocean tried to work more cheaply, which contributed to the explosion and oil leak. It stated that decisions made by these companies saved them time and money. BP said it had already made changes to improve safety before the commission's report. Transocean blamed BP for making the decisions before the explosion and government officials for not stopping them. Halliburton said it followed BP's orders when it injected cement into the well and criticized BP for not running a cement bond log test. The report listed nine mistakes by BP, including not testing the strength of the cement and ignoring a failed pressure test. It concluded that the accident could have been avoided and was caused by mistakes made by BP, Halliburton, Transocean, and government officials who did not properly regulate the drilling.

On March 23, 2011, BOEMRE (formerly MMS) and the USCG published a detailed study of the blowout preventer, done by Det Norske Veritas. The report said the main cause of failure was that the blind shear rams did not fully close and seal because part of the drill pipe buckled between the shearing blocks.

A US government report from September 2011 said BP was ultimately responsible for the spill, and Halliburton and Transocean shared some blame. The report stated the main cause was a defective cement job, and all three companies were responsible in different ways. It said the disaster was caused by failures to prevent a well blowout, poor risk management, last-minute plan changes, and inadequate emergency training.

On June 16, 2010, after BP executives met with President Obama, BP created the Gulf Coast Claims Facility (GCCF), a $20 billion fund to pay claims from the Deepwater Horizon spill. The fund was used for natural resource damage, state and local response costs, and individual compensation, but not for fines or penalties. Before the GCCF, BP paid emergency compensation from an initial fund.

The GCCF was managed by attorney Kenneth Feinberg. It started accepting claims on August 23, 2010. On March 8, 2012, after BP and a team of lawyers reached a class-action settlement, a court-appointed administrator, Patrick Juneau, took over. Before this, more than one million claims from 220,000 individuals and businesses were processed, and over $6.2 billion was paid. About 97% of payments went to people in Gulf States. In June 2012, the GCCF was replaced by a court-supervised settlement program. During the transition, an additional $404 million was paid.

The GCCF and its administrator, Feinberg, faced criticism for slow payments, lack of transparency, and some claimants being denied or underpaid. An independent audit by BDO Consulting found 7,300 claimants were wrongly denied or underpaid, leading to an extra $64 million in payments. The Mississippi Center for Justice helped 10,000 people with legal support for the claims process.

In popular culture

• On 28 March 2011, the TV program Dispatches showed a documentary by James Brabazon called BP: In Deep Water, which discussed the oil company BP, its history with oil spills in the Gulf of Mexico, and its connections with governments.
• In April 2012, the National Geographic Channel’s documentary series Seconds From Disaster included an episode titled “The Deepwater Horizon” that described the accident.
• In 2012, Beyond Pollution 2012 traveled across the Gulf Coast to interview environmental experts, government officials, fishermen, scientists, drilling engineers, and BP workers. The program examined the economic and health effects of the oil spill.
• In 2012, The Big Fix documented the April 2010 Gulf of Mexico oil spill that followed the sinking of the Deepwater Horizon oil rig.
• In 2014, The Great Invisible, created by Margaret Brown, focused on the social effects of the disaster on people whose lives were affected. It later aired on 19 April 2015 as season 16, episode 14 of Independent Lens.
• In 2014, Vanishing Pearls: The Oystermen of Pointe a la Hache, Louisiana showed a town of about 300 people struggling to survive after the oil spill destroyed their oyster crops and caused financial problems.
• In 2016, Pretty Slick documented the cleanup efforts and the experiences of people in four Gulf states following the largest man-made environmental disaster in U.S. history.

• In 2016, After the Spill, produced by Jon Bowermaster, explored how the disaster affected local economies, human and animal health, and food sources. It also examined the use of Corexit, a chemical used to treat oil, and followed up on earlier research about Louisiana’s water before the spill.
• In 2016, Dispatches from the Gulf, created by Hal Weiner, followed scientists studying the oil spill’s effects on the Gulf.

• In 2012, the HBO TV series The Newsroom included a pilot episode titled “We Just Decided To” that showed characters reporting on the Deepwater Horizon story.
• The 2015 film The Runner, directed by Austin Stark and starring Nicolas Cage, told a fictional story about a politician and his family living in the aftermath of the Deepwater Horizon disaster.
• In 2016, Deepwater Horizon, a film about the explosion, was released. It was directed by Peter Berg and starred Mark Wahlberg, Kurt Russell, and John Malkovich.

• In 2011, Jimmy Fallon, who hosted Late Night with Jimmy Fallon, created a protest song called “Balls In Your Mouth” about tarballs still floating in the Gulf of Mexico. He performed the song on his show with guest singers, including Eddie Vedder, Russell Crowe, Brad Paisley, and Florence Welch. A live version with Eddie Vedder was included in Fallon’s comedy album “Blow Your Pants Off.”
• In 2011, the band Rise Against released a song titled “Help Is on the Way” on their album Endgame. The song discussed the slow response to aid in disaster areas, with lyrics referencing the Macondo spill and Hurricane Katrina.
• In June 2011, Canadian musician City and Colour released a song titled “At the Bird’s Foot” on his album Little Hell. The song described the Deepwater Horizon event and criticized the greed of those involved.
• On 6 November 2012, Pete Seeger and Lorre Wyatt released the music video and single “God’s Counting on Me, God’s Counting on You”. They recorded and filmed the song live aboard the Hudson River Sloop Clearwater in 2010, shortly after the Deepwater Horizon oil spill. The song mentioned the spill.
• In 2012, American singer-songwriter Andrew Bird released the song “Hole in the Ocean Floor”, which was inspired by the Deepwater Horizon oil spill.

• The Deepwater Horizon oil spill was mentioned in a 2010 episode of South Park titled “Coon 2: Hindsight”. The episode showed a BP drilling vessel causing an oil spill in a protected area. A crew member said, “Oh, don’t tell me we did it again?” Later, BP drilled again and opened a portal to another dimension, causing creatures to attack the Gulf. They later drilled on the Moon to change Earth’s gravity, but this caused Cthulhu to emerge. Each time BP drilled, Tony Hayward released a “we’re sorry” campaign. The oil spill was not fixed until two episodes later.
• In a Beavis and Butt-Head season 8 episode titled “Spill”, the characters traveled to the Gulf to help clean baby birds affected by the oil spill. They mistakenly believed they would be having sex with “filthy chicks” and volunteered for the trip.