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Deepwater Horizon Oil Spill

One of the worst environmental disasters in US history

Deepwater Horizon Oil Spill

Photo by Keely Merritt, The Historic New Orleans Collection

A group of some thirteen oiled pelicans in a wooden crate.

The Deepwater Horizon oil spill in the Gulf of Mexico is considered one of the worst environmental disasters in our nation’s history. On April 20, 2010, BP’s Macondo well at Mississippi Canyon 252 blew out, killing eleven workers onboard the doomed Deepwater Horizon drilling rig and causing the largest oil spill in US history. A series of human errors led to catastrophic failure of the well, its control systems, and ultimately the rig itself. The incident brought to light deficiencies in offshore safety and risk management at the corporate level, and the lack of rigid government oversight in the offshore sector. The accident also highlighted the inability of the industry and government agencies to respond effectively to such a complex underwater problem and the massive oil spill that ensued. The disaster had a profound effect on the economy, ecology, and way of life for people along the Gulf Coast, particularly in Louisiana.

Human Error

The immediate cause of the accident was a failure to contain rising pressures in the Macondo well that resulted in a blowout and a deadly explosion on the rig. Trouble began when the crew of the Deepwater Horizon, a state-of-the-art semi-submersible drilling rig owned by Transocean, attempted to temporarily plug and abandon the Macondo discovery well. In a rush to finish the job and move the rig off of location, the engineers cut corners and did not adequately plug the well with cement. As a result, hydrocarbons (a mixture of oil and gas) escaped undetected through the poorly cemented well and shot up the drilling riser pipe that connected the well on the seafloor to the rig above. Known as a “kick,” this accidental release of dangerous gas from the well caused a series of explosions on the rig. The blow-out preventer—the fail-safe equipment designed to stop the flow of gas out of the well—failed to seal the well during the emergency. The fires engulfed the rig, forcing the surviving crew members to evacuate. Two days later, the rig sank in five thousand feet of water. Oil gushed out of the crumbled riser pipe on the seafloor for eighty-seven days, eventually releasing millions of barrels of oil into the Gulf.

Capping the Well

In the immediate aftermath of the accident, it became apparent that neither BP, nor the industry at large, had developed the technology and procedures to contain this kind of massive oil leak at such great depths. Nor did federal regulators require that they have the technology to address this type of disaster. Over the course of three months, experts from industry and government made several failed attempts to cap the leak. Experimental concepts, such as the “Top Hat” and “Junk Shot,” were quickly engineered and deployed, but had minimal effect. The drilling of secondary relief wells finally intersected the Macondo well and filled it with cement to stop the leak. Throughout the ordeal, the world watched in dismay as underwater cameras captured footage of the uncontrolled gusher. The estimates of total oil released into the Gulf varied, but the generally accepted figure is five million barrels. By comparison, the 1989 Exxon Valdez disaster in Alaska spilled approximately 260,000 barrels of oil.

The Cleanup Response

Within days of the accident, the US Coast Guard and BP established command posts along the Louisiana Gulf Coast to coordinate the massive cleanup. This included mobilizing boats to deploy containment boom near the shorelines and specialized skimmers to collect the oil at sea. The US Air Force, using C-130 airplanes, deployed tons of chemical dispersants over the oil slick in order to break up the oil before it reached the coast. Much of the oil sank to the seafloor. Ultimately, tens of thousands of individual responders, including state and federal agency personnel and local contractors, took part in the unprecedented response effort. BP’s Vessels of Opportunity program hired out-of-work local fishermen and their boats to assist with the cleanup. As the crisis intensified and oil reached Louisiana’s fragile coastline, friction between the federal government and state and local authorities boiled over. There were arguments over distributing the limited supply of boom and hiring non-resident contractors to work the cleanup. State officials took to the media, almost daily, to complain and to advocate for various projects, such as the controversial emergency sand berm project off Louisiana’s southeastern coast. This expensive project had little effect on the overall containment effort.


The political and regulatory fallout from the accident was swift. On May 27, the federal government ordered a six-month moratorium on offshore drilling, citing safety concerns over current blow-out-preventer technology. At the same time, the White House called for the formation of the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling to study the causes of the disaster and to provide recommendations for reforms in the offshore industry. In its final report, the commission called for fundamental changes in all aspects of offshore safety, leasing, regulations, and operations. A new federal agency, the Bureau of Ocean Energy Management, replaced the troubled Minerals Management Service in order to eliminate bureaucratic shortcomings and to better manage the offshore industry. A series of reforms required industry improvements in safety systems, risk management, and technical capabilities to effectively address deepwater well-containment problems in the future.

Impacts to the Gulf Coast

The economy along the Gulf Coast took a dramatic hit from the oil spill. The seafood and tourism industries ground to a halt and did not recover for the remainder of the year. The drilling moratorium and the implementation of new federal agency reforms and oversight caused a significant downturn in Louisiana’s oil-driven economy. The estimated $30 billion that BP paid out for claims and cleanup costs provided some relief to those affected. In addition, the company agreed to pay $500 million to research institutions to study the long-term impacts of the spill on the ecosystem. Perhaps the defining legacy of the BP oil spill will be the Gulf Coast Restoration Fund, which will contribute $19 billion over the course of fifteen years to fund the economic and environmental recovery efforts in the Gulf Coast. For Louisiana, the BP restoration funds will provide an unprecedented level of financial and managerial support for coastal restoration—$7 billion from the fund will go towards the state’s Coastal Master Plan.