BP Oil Spill: Facts and Environmental Impact

2010 Deepwater Horizon spill dumped 134 million gallons of oil into the Gulf of Mexico

Fire that resulted from the explosion on the Deepwater Horizon oil rig
Fire that resulted from the explosion on the Deepwater Horizon oil rig.

US Coast Guard / Public Domain / Wikimedia Commons

The BP Oil Spill was the longest and most severe offshore oil spill in United States history. On April 20, 2010, the Deepwater Horizon oil rig, operated by the BP oil company, exploded, killing 11 people and sending 134 million gallons of crude oil straight into the waters of the Gulf of Mexico.

What followed was an environmental disaster unlike anything the world had seen before, defined by unprecedented numbers of wildlife deaths, impact to the surrounding communities, and damages to ecosystems that are still struggling to recover more than a decade later. Prior to 2010, the nation’s worst oil spill had been the Exxon Valdez, which spilled 11 million gallons of oil into Alaska’s Prince William Sound on March 24, 1989.

BP Oil Spill Facts

  • The BP Oil Spill was the worst offshore oil spill in United States history.
  • From April 20, 2010 to July 15, 2010, an estimated 134 million gallons of crude oil spilled into the Gulf of Mexico.
  • A series of catastrophic failures led to an explosion on the Deepwater Horizon oil rig, causing the death of 11 people and a massive leak in an underwater wellhead.
  • The rig was being leased and operated by the BP oil company.

Deepwater Horizon Oil Spill

The rig exploded in the northern Gulf of Mexico, causing a leak in BP’s Macondo wellhead located 1,525 meters (almost a mile) below the water’s surface. The well wasn’t capped until July 15, 2010, almost three months after the initial explosion.

Gulf Oil Spill Spreads, Damaging Economies, Nature, And Way Of Life
Two egrets search for food in a canal beside an oil contaminated beach June 14, 2010 in Grand Isle, Louisiana. Spencer Platt / Getty Images

By that time, an estimated 3.19 million barrels worth of crude oil had escaped into the Gulf, reaching the coasts of Texas, Louisiana, Mississippi, Alabama, and Florida. For 87 days straight, residents watched helplessly as oil continued to leak into the ocean while BP struggled to contain the damage. Constant press coverage depicted images of birds smothered in thick oil and sea turtles swimming through rust-colored sludge, but the true scale of the environmental disaster wasn’t realized until much later.

Oil Rig Explosion

Though the cause of the explosion wasn’t revealed immediately, initial reports listed 11 workers as missing and seven injured, with the rig burning about 52 miles southeast of the tip of Louisiana. The rig’s owner was the world's largest offshore drilling contractor, Transocean Ltd., though it was being leased by oil company BP Plc at the time. The Coast Guard used helicopters, ships, and planes to search the Gulf for signs of lifeboats or survivors, while environmental teams waited on standby to assess the damage once the fire was extinguished. By the morning of April 22nd, the fire was out and the Deepwater Horizon drilling rig had sunk to the bottom of the Gulf. Louisiana declared a state of emergency on April 29th, and shortly after, President Obama announced an immediate ban on new drilling in the Gulf.

Containment Attempts

Shortly after, the U.S. coast guard started to evaluate the extent of the damage using deep-sea remote cameras. At first, officials estimated that oil would leak into the Gulf at a rate of 1,000 barrels per day. BP and government agencies began the process of discharging floating booms to contain surface oil and releasing thousands of gallons worth of chemical dispersants to break down underwater oil and prevent wider spread. Shortly after, controlled burns were initiated on the giant oil slicks that had formed on the water’s surface.

USA - Deepwater Horizon Disaster - Contianment Efforts
Smoke rises from a controlled burn of oil on the surface of the water near the site of the BP Deepwater Horizon oil spill in the Gulf of Mexico, Sunday, July 11, 2010. Corbis via Getty Images / Getty Images

For the following weeks, there were several attempts to contain the leak. The first came on May 6, when BP placed three containment domes over the broken pipe. Almost immediately, the domes were clogged by a buildup of methane hydrates and were deemed ineffective.

From May 26 to May 28, BP attempted a process known as “top kill” in an attempt to plug the leak and kill the well completely. Thousands of barrels worth of heavy drilling mud were pumped into the top of the well at high pressures to force the oil back down into the earth. They attempted the process three times over three consecutive days, all of which proved unsuccessful. In mid-May, BP reported that 5,000 barrels worth of oil were being leaked per day, though experts put the actual figure between 20,000 and 100,000. In June, BP made its first significant breakthrough thanks to a cap containment system that captured a portion of leaking oil and brought it to the surface for processing.

Leak Contained

BP used underwater robots to remove the cap installed in June and replace it with a new tighter sealed containment cap in July. On July 15, after 87 days of oil spewing into the Gulf, BP announced a successful test of the cap and the official containment of the leak.

Overhead the Deepwater Horizon oil rig leak
Kris Krüg / Getty Images

Cleanup Efforts

The cleanup process primarily involved the application of subsurface chemical dispersants to break up oil so that it could be absorbed easier (since oil and water don’t mix). The magnitude of chemical dispersant was unique to the BP Oil Spill, and 10 years later, scientists are still conflicted as to whether the dispersants even helped at all. By the time the leak was capped, a total of 11,000 square kilometers (4,200 square miles) of the ocean surface and 2,000 kilometers (1,243 miles) of coastline — half of which was in Louisiana — had been impacted by oil, gas, and dispersants. Visible oil washed up on coastal marshes and beaches over 80 kilometers (50 miles) from the spill site. Meanwhile, conservationists attempted to clean oiled creatures, especially birds, and release them back into the wild (which some experts argued wouldn’t make a difference either).

Gulf Coast Battles Continued Spread Of Oil In Its Waters And Coastline
Oily absorbent material along with containment booms, part of the efforts to clean the beach from effects of the Deepwater Horizon oil spill on June 29, 2010 in Elmer's Island, Louisiana. Joe Raedle / Getty Images

Prior to the Deepwater Horizon disaster, scientists had a general understanding of how oil spills could impact coastal environments and the organisms who live there. The BP Oil Spill, however, was so large in scale and duration that it posed unparalleled challenges to assessing the damage and planning recovery efforts.

Environmental Impact

Just months after the spill was contained, oceanographers compared population densities of foraminifera, a single cell organism that is an important primary food source for the Gulf’s bottom-dwelling marine life, in three sites. They found that populations were 80% to 93% lower in the two sites affected by the oil spill. Anywhere from 2% to 20% of the oil spilled was deposited into sediments on the seafloor. Less than a year after the leak, a study in the Society for Conservation Biology journal estimated that the true death toll of marine animals could be 50 times more than the numbers reported.

BP Oil Spill seen from NASA's Terra satellites
NASA/GSFC / Public Domain / Wikimedia Commons

The extent of the damage from the spill, so big that it could be seen from space, is still being studied to this day. In 2020, researchers at the University of Miami discovered that toxic concentrations of oil actually reached as far as the West Florida shelf, upper Texas shores, and the Florida Keys. Another study estimated that the spill caused a 38% decline in the number of different species in northern Gulf reef fish communities.

Coral Reefs

Low light mesophotic reefs, a type of coral ecosystem found 100 feet to over 490 feet beneath the ocean’s surface, serve as important habitats for deep-sea fish species. According to the U.S. National Oceanic and Atmospheric Administration (NOAA), the reefs also serve as a source to reseed and replenish other coral species that live in shallower water.

Scientists studied Gulf mesophotic reef systems in 2010, 2011, and 2014, comparing it to data from one and two decades before the spill. Post spill, injuries were found in 38% to 50% of large gorgonian coral at sites near the Macondo well, compared to just 4% to 9% before the Deepwater explosion. The odds of further injury were 10.8 times higher at sites near Macondo after the spill and were unchanged in the areas studied further from the spill site. When scientists studied the coral again in 2014, they found further declines in coral conditions with no evidence that the damage was caused by other background stresses like fishing activity, debris, and predation.

Similarly, large reef fish abundance decreased by 25% to 50% in the most affected areas, while populations of large bottom-feeding fish decreased by 40% to 70%. Scientists think certain populations could take over 30 years to fully recover.


NOAA veterinarian prepares to clean an oiled Kemp's Ridley turtle
NOAA's National Ocean Service / Wikimedia Commons / CC BY 2.0

Before 2010, the endangered Kemp’s ridley sea turtle was on the road to recovery thanks largely in part to a restoration program in Mexico and the United States. The Bi-National Recovery Plan predicted a population growth rate of 19% per year between 2010 and 2020 if turtle conservation efforts remained constant. Instead, survival rates plummeted and the number of nests declined by 35%. Studies linked the BP oil spill to a surge of sea turtle strandings in the northern Gulf of Mexico with a majority in Alabama, Mississippi, and Louisiana.

Sea Birds

Following the spill, patrollers recovered thousands of dead sea birds from the areas surrounding the site, but it wasn’t until 2014 that a team of experts accurately estimated the total number of deaths. They found that bird mortalities numbered between 600,000 and 800,000, mostly affected four species: the laughing gull, the royal tern, the northern gannet, and the brown pelican. The laughing gull was by far the most affected, with 32% of the entire northern Gulf of Mexico population killed as a result of the spill.


A deadly toll on dolphin and whale populations contributed to the largest and longest marine mammal mortality event ever recorded in the area. Between 2010 and 2014, there were 1,141 cetacean strandings recorded in the northern Gulf of Mexico, with 95% found dead. Bottlenose dolphins especially were killed both as a direct result of oil pollution and from long-term adverse health effects. Studies on the species conducted from 2010 to 2015 found that reproductive success rates for bottlenose dolphin females were less than a third of those in areas not impacted by the spill.

Aftermath and Legacy

Gulf Oil Spill Spreads, Damaging Economies, Nature, And Way Of Life
Spencer Platt / Getty Images

On May 30, over a month into the disaster, President Obama’s assistant on energy and climate change told NBC that BP had a financial interest in undermining the damage since they pay a penalty based on the amount of oil leaked per day. That same week, BP CEO Tony Hayward was criticized for telling the press: “I would like my life back,” in the wake of the explosion that killed 11 of his own employees. Earlier, Hayward had downplayed the spill in an interview with The Guardian. "The Gulf of Mexico is a very big ocean,” he said. “The amount of volume of oil and dispersant we are putting into it is tiny in relation to the total water volume.”

Federal Response

In response to the disaster, the Obama administration created the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling on May 21, 2010, which recommended safety rules, standards for company accountability, and environmental regulations. Additionally, he signed an executive order that promoted environmental stewardship for bodies of water within the United States territory. These policies were, according to the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE), some of “the most aggressive and comprehensive reforms to offshore oil and gas regulation and oversight in U.S. history."

A 2011 investigation conducted by BOEMRE and the U.S. Coast Guard found the central cause of the Deepwater Horizon explosion to be a faulty cement base at the 18,000 foot deep well. The BOEMRE director said that both BP and Transocean violated multiple regulations in order to save money and cut corners.

An oil spill in the Gulf of Mexico
Kris Krüg / Getty Images

Economic Toll

In late 2010, about 2,000 residents in Louisiana and Florida were interviewed following the disaster, with one quarter expressing that their environmental views had changed since the spill. One estimate found a $23 billion economic loss over a three-year period for the tourism industry in Florida, as coastal property owners reported cancellations of vacation rentals even if they hadn’t seen any oil in the area. By February 2011, BP had compensated $3.3 billion to residents, fishermen, and business owners, though many other claims were denied.

Congress passed the RESTORE Act (Resources and Ecosystems Sustainability, Tourist Opportunities, and Revived Economies of the Gulf Coast States) in July of 2012, establishing a Gulf Coast Ecosystem Restoration Council. The act dedicated 80% of administrative and civil penalties related to the Deepwater Horizon spill into a dedicated trust fund and researched the best ways to use the funds to restore and protect the Gulf Coast region.

Gulf Coast Battles Continued Spread Of Oil In Its Waters And Coastline
Joe Raedle / Getty Images

In 2012, BP pleaded guilty to 14 felony counts and was subsequently fined $4 billion. Half of the funds reported went towards environmental restoration in the Gulf as well as oil spill response training and prevention. The owner of the rig, Transocean, pleaded guilty to charges in 2013, adding another $300 million.

The criminal case resulted in the largest criminal penalty with a single entity in United States history. On April 4, 2016, a federal district judge approved a $20.8 billion settlement, the largest environmental damage settlement in the history of the United States. Seven years after the spill, a study measured the economic cost of the disaster and found an ultimate cost to BP of $144.89 billion in the United States. This included the $19.33 billion in 2016 settlements, contingent liabilities of $700 million, and $689 million in legal fees.

The tragedy aboard the Deepwater Horizon was a bleak display of the unbelievable environmental destruction that potential oil spills continue to present. The spill showed us ways in which nature responds to oil pollution at a time when the Earth already faces extreme ecological challenges and fragility. It also offered a grim opportunity to study the long-term effects of widespread oil spills and paved the way for some of the biggest oil spill cleanup technology advancements — technology that will aid in the next inevitable spill. If science has taught us anything, it is that the consequences of oil spills can continue to affect the environment for generations.

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