an offshore platform at sea representing the deepwater horizon

What happened at the Deepwater Horizon?

The Deepwater Horizon disaster of 2010 caused 134 million gallons of oil to pour into the Gulf of Mexico, killing 11 people and injuring 17 more. It had devastating ecological and economic impacts from Texas to Florida. The consequences of this event are still affecting marine life and residents along the Gulf Coast today. An investigation revealed that what happened at the Deepwater Horizon was completely preventable and was the result of failures in communication, poor regulatory practices for deepwater drilling, and a disregard for warning signs. 

From the loss of income to negative health outcomes and death, hundreds of plaintiffs and their families who felt the impact of the Deepwater Horizon crisis filed suit against the responsible parties. Those companies have since paid out billions of dollars in reparations for what has become known as the largest offshore oil spill in United States history.  

What Happened on the Deepwater Horizon?

On April 20, 2010, an explosion on the Deepwater Horizon drilling platform engulfed the oil rig in flames. It ultimately sank on April 22, 2010, but not before nearly three dozen people were injured or killed. The event also led to a catastrophic oil spill that wasn’t contained for three months, causing unprecedented damage to natural resources in the Gulf.

Residents who relied on tourism and the natural beauty of the Gulf to support their businesses suffered economic damages. Many restaurants and local attractions were forced to close or sustained considerable losses as tourism slowed following the disaster.

At the time of the accident, the Deepwater Horizon, a semi-submersible offshore drilling rig, was operating in the Macondo Prospect, an oil and gas prospect 41 miles off the southeast coast of Louisiana. The owners of the Deepwater Horizon had been contracted to drill a 20,000-foot exploration well into the Macondo reservoir. The goal was to determine whether oil could be produced from four miles below the ocean’s surface in this part of the Gulf of Mexico.

By April 2010, the Deepwater Horizon had been drilling for four months, at an estimated cost of $1 million per day. Unexpected delays related to drilling through weak rock formations in the area had put the rig and its crew six weeks behind schedule. Now they were finally preparing to move the rig to drill at another location outside of the Macondo Prospect.

The plan was to temporarily cap the Macondo well until it was needed for future oil production. Oil executives expected the well to eventually produce approximately 50 million barrels of oil — a value of $5 billion. Top executives were actually on board the Deepwater Horizon the day of the explosion celebrating the oil rig’s seven-year safety record.

What Caused the Explosion on the Deepwater Horizon?

The Macondo well was dug 5,000 feet beneath the ocean’s surface. There were problems from the very beginning of the project, including:

  • A drillpipe that got stuck during drilling
  • Drilling mud leaking out of the well through cracks in the surrounding rock
  • The presence of gas at unexpectedly high pressures, which entered the well from the surrounding rock formation

All of these issues caused significant delays in drilling. In fact, the Macondo project was $58 million over budget at the time of the catastrophe. Everyone involved was feeling considerable pressure to finish the project without further delays or expense. At the beginning of April, engineers working on the project determined that the risks involved in further drilling were very high. The concern was that additional fracturing of the rock formation was likely to occur if they continued to drill.

Although the planned depth of the Macondo well was supposed to be 20,200 feet, the engineers decided to stop drilling at 18,360 feet due to these concerns. The next step was to install a steel production casing into the final section of the well in order to pump cement around the well. The purpose of the cement was to seal gas and oil into the well until it was time to produce oil.

Flaws in Design and Execution

Engineers were concerned that the cement would place additional pressure on the already fragile rock formation surrounding the well, leading to cracks in the formation. They were also in a hurry to finish this job and move on to the next one. As a result, they devised a new plan to reduce stress on the rock formation and cut time off the job.

Unfortunately, flaws in the design and execution of this plan ultimately led to the Deepwater Horizon’s tragic end, including:

  • Failing to properly condition the mud produced by drilling to a low viscosity state necessary for settling on the ocean floor
  • Choosing a lower-than-usual value for the rate necessary to pump the cement around the well, which was supposed to displace the mud
  • Reducing the amount of cement used to prevent the cement column from being too high
  • Using a foam cement that contained tiny nitrogen gas bubbles to reduce the density of the cement

The choice to change cement material ended up being perhaps the gravest mistake engineers made. When not set correctly, foam cement is porous and permeable to other substances, making it weaker than the cement normally used for this purpose. Despite lab tests that showed unstable behavior, engineers went ahead with their decision to use the foam cement.

They also made changes to the procedure typically used to move the Deepwater Horizon off of the well.

Flaws in Testing

In order to test the integrity of the Macondo well, engineers used a material not normally used or tested for this purpose. Initial testing indicated that there was too much pressure building up in the well any time the drill pipe was closed off. Instead of accepting that there was a well integrity issue, examiners used a different test that yielded the results they wanted.

The reality was that the cement had not secured the well as it was supposed to. Instead of seawater displacing the drilling mud in the well, inflowing gases expanded in the well and quickly rose 18,000 feet toward the Deepwater Horizon rig. The gas pushed the mud up the well as it expanded.

Ignored Warnings

Despite indications that something was very wrong, attempts to successfully complete the project continued until mud and gas began spilling onto the Deepwater Horizon’s drill floor.

Emergency Containment Failures

Standard procedure was to seal off the well and route the flow of mud and gas over the side of the Deepwater Horizon. Instead, the crew decided to route the flow into a separator that was too small for the volume of material coming up from the ocean floor. Gas spread over the floor of the Deepwater Horizon and was ignited by the rig’s pump motors, causing the first explosion.

The crew continued its fruitless efforts to close the well. Emergency system control pods responsible for closing down the well and preventing further damage failed to activate. During a later investigation, it was discovered that poor maintenance of the emergency systems, including low batteries and other defects, was responsible for the system’s failure.

When all else failed, the crew initiated emergency evacuation of all personnel from the Deepwater Horizon, but not before several fatalities and injuries occurred.

Summary of Failures at the Deepwater Horizon

Investigations by the United States government and other agencies concluded that the following issues contributed to the explosion, fire, and sinking of the Deepwater Horizon oil rig and to the environmental impacts that followed:

  • Difficulties with drilling
  • Failure to contain the uncontrolled release of flammable, high-pressure gases in the well
  • Poor decision-making and oversight
  • Poor maintenance
  • Poor design
  • Failures in management and communication
  • The absence of a formal decision-making process, checks and balances, and written procedures
  • Insufficient training for operators and contractors on the project
  • Lack of peer and expert reviews of risks and management of changes
  • Conflicts between best practice, risk mitigation, and a desire to save time and money
  • Regulatory failures by the government that didn’t address risk management in deep-sea drilling

The Aftermath of Deepwater Horizon

Attempts to stop the flow of oil and cap the well failed. Oil leaked from the ruptured head of the Macondo well and into the Gulf of Mexico for 87 days. This equated to nearly four Olympic-sized swimming pools worth of oil spilling into the ocean each day for nearly three months. 

In addition to harming ecosystems and wildlife, as well as the economic damages to the fishing and tourism industries, there were concerns about health hazards to coastal residents and oil cleanup crews. Chemicals that were sprayed on the oil and gas to break it up and reduce the spread may have ultimately worsened the effects on marine life and caused additional ecological damage and health concerns.

Environmental Damages

The Deepwater Horizon incident was an ecological disaster for the ocean and coastline along the Gulf of Mexico. It affected 68,000 square miles of water and 1,000 miles of coastline, including many beaches. Fish, birds, bottom-dwelling organisms, deep sea coral, marine mammals, sea turtles, wetlands, beaches, and other ocean ecosystems were severely impacted and still haven’t returned to normal today.

Economic Losses

Coastal residents and business owners who suffered economic losses from the Deepwater Horizon oil spill were eligible to seek compensation through the Gulf Coast Claims Facility. They either filed for an emergency claim or a long-term settlement in the years following. Plaintiffs who accepted an emergency payment are still able to sue for additional or future losses, while those who took long-term settlements are not.

Health Hazards

Thousands of people who helped with cleanup and recovery efforts may have been exposed to harmful substances called hydrocarbons in the oil itself and in chemicals used to clean it up. Initial attempts were made to contain the spilled oil using a chemical called Corexit, which contained 2-butoxyethanol. Corexit was meant to disperse and prevent oil from evaporating into the water and ground. Exposed individuals expressed concerns about 2-butoxyethanol and its link to certain cancers, as well as respiratory and cardiovascular disease. Subsequent studies later revealed correlations between 2-butoxyethanol and the following:

  • Thrombocytopenia (reduced platelet count)
  • Irritation to eyes and skin
  • Chronic rhinosinusitis
  • Reactive airway dysfunction
  • Blood diseases
  • Kidney disease

Other symptoms of Corexit exposure include skin rashes, coughing up blood, wheezing, migraines, burning eyes, discharge from the ears, cognitive decline, anxiety attacks, and memory loss. The oil companies assured people that Corexit was safe to use and failed to provide protective gear. Seven million liters of Corexit were dropped from airplanes over the Gulf of Mexico in the days following the oil spill.

Scientists expressed concerns at the time about exposure to the heavy metals found in Corexit, including benzene, hexane, and toluene, all known carcinogens. Even people not directly involved in the cleanup efforts may have been affected by Corexit because the droplets can be carried great distances by the wind, sickening anyone who inhales them. 

Additionally, airborne and skin exposure to hydrocarbons from oil itself can result in:

  • Coma
  • Seizures
  • Irregular heartbeat
  • Kidney and liver damage
  • Permanent and irreversible lung damage
  • Death

Affected individuals have filed hundreds of lawsuits in both state and federal courts against the companies involved in the Deepwater Horizon oil spill, and many more are expected in the future. Plaintiffs claim that their health was jeopardized due to their exposure to 2-butoxyethanol and hydrocarbons.

What Were the Legal Consequences of the Deepwater Horizon Oil Spill?

Following the Deepwater Horizon oil spill, the parties found to be responsible faced both criminal and civil investigations and penalties. The United States government filed a complaint in District Court in December 2010 and launched criminal investigations of all companies involved. Investigations focused mainly on whether relationships between corporate officials and federal regulators were the cause of the Deepwater Horizon accident and a breach of environmental laws. Lawsuits included claims under the Clean Water Act and the Oil Pollution Act.

Investigators also discovered that procedures used during the attempted capping of the Macondo well may not have undergone any formal risk assessment before they were put in place.

The main party and developer of the drilling site agreed to plead guilty to criminal charges and to pay up to $1 billion for restoration projects in the Gulf of Mexico. They also released a statement that was filed with the court agreeing to pay all legitimate claims from plaintiffs, regardless of the Oil Pollution Act’s limits on liability. But that was just the beginning.


  • February 17, 2012: A $90 million civil settlement is awarded
  • February 22, 2012: A court order grants a partial summary judgement of liability for the spill, paving the way for future lawsuits
  • November 15, 2012: $4.5 billion criminal plea agreement
  • January 3, 2013: A $1 billion civil settlement is awarded and another defendant reaches a $400 million criminal plea agreement
  • June 4, 2014: The Fifth Circuit Court of Appeals affirms the summary judgement ruling
  • September 4, 2014: Trial begins
  • November 5, 2014: The Fifth Circuit Court of Appeals denies a panel reconsideration and reaffirms the summary judgement ruling in the case
  • January 9, 2015: The Fifth Circuit Court of Appeals denies the defendant’s petition to rehear the case
  • February 19, 2015: There’s a ruling on the maximum dollar-per-barrel penalty amount allowed
  • October 2015: A plan is drafted to allocate $8.8 billion for restoration from a proposed civil settlement of $14.9 billion
  • November 30, 2015: $159.5 million civil penalty ruling
  • April 2016: A federal district judge approves an environmental damage settlement of $20.8 billion to cover damages for harm to natural resources that resulted from the spill. It was the largest civil settlement ever awarded.

In order to allocate settlement funds associated with the Deepwater Horizon spill to all of the states impacted, The Gulf Coast Ecosystem Restoration Council was formed. The Restoration Council is an independent federal agency that includes the governors of Alabama, Florida, Louisiana, Mississippi, and Texas, as well as the secretaries of the U.S. Departments of the Interior Army, Commerce, Agriculture, and Homeland Security and the administrators of the U.S. Environmental Protection Agency.

Private Party and Class Action Settlements

Private citizens have also hired offshore injury lawyers to file class action lawsuits for medical claims and economic damages they sustained as a result of the Deepwater Horizon incident. The U.S. District Court for the Eastern District of Louisiana established a website to track private litigation in the Deepwater Horizon case. Plaintiffs in these cases seek:

  • Compensation for injuries sustained in the Deepwater Horizon incident
  • Economic damages caused by the explosion

Other Outcomes

The Deepwater Horizon oil accident led to improvements in the operation and maintenance of emergency offshore drilling systems and the devices used to cap wells in worst-case scenarios like what happened at the Macondo well in 2010. A massive overhaul of offshore oil and gas regulatory procedures took place in the US, with many regulations changed to more closely mirror other countries’ deep-sea drilling safety practices. 

What Are the Long-Term Effects of the Deepwater Horizon Crisis?

On July 15, 2010, the valves of the Macondo well were successfully closed and oil stopped gushing into the Gulf of Mexico. However, the cleanup from Deepwater Horizon went on for years, with the effects still evident in the Gulf today, including:

  • Fish in the region are still contaminated with hydrocarbons.
  • The spill turned out to be more extensive than first suspected, with signs of impact reaching all the way to the southernmost tip of Florida.
  • Tens of thousands of mostly low-income workers in the fishing industry are still suffering from respiratory illnesses associated with the chemical Corexit. Some have even died as a result of their exposure from respiratory and other cancers.

Perhaps most disturbing, the commission responsible for investigating the Deepwater Horizon accident predicted that another similar event is inevitable. Members of the commission have publicly stated that their recommendations have not been given serious consideration. Oil drilling continues to move further offshore and into deep water, increasing the odds that something like Deepwater Horizon could happen again.

Additionally, safety rules put in place right after the Macondo well explosion have since been rolled back in favor of more lenient safety inspections and lax enforcement policies. The Gulf of Mexico is especially vulnerable to future incidents involving deep sea oil drilling because:

  • 17% of oil production in the United States comes from the Gulf of Mexico.
  • More than 1,800 oil rig platforms are connected to oil refineries along the Gulf Shore.
  • 41,000 kilometers of oil pipeline runs through the Gulf. 
  • A 2013 study found that for every additional 100 feet that an oil well’s depth increases, spills and injuries to the crew increase by 8.5%.
  • Between 2018 and 2019, the amount of oil spilled on American shores has increased six times over the past two years.
  • Between 2007 and 2018, the number of fires and explosions that took place in American waters increased to an average of 115, approximately one every three days.
  • During that same time period, 50 fatalities occurred.
  • Small leaks from existing wells have enough oil volume to continue to seep oil into the ocean for the next 100 years, eventually surpassing the Macondo well in barrels of oil spilled.

If you believe that you have been impacted by the Deepwater Horizon oil spill and were living in the vicinity during or following the event, you may be eligible to join a class action lawsuit and recover damages for your pain and suffering, economic losses, and medical expenses. 

Offshore accidents like the Macondo oil well disaster have the potential to shift the course of your life and that of your family. If your health or ability to work have been jeopardized, the government has money available to help. An offshore injury lawyer in Louisiana or Texas can help you understand your rights as they relate to litigation in the Deepwater oil rig case. The only way to ensure that accidents like this don’t happen again is to petition the courts for a fair settlement. 


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