Due to new technologies and our knowledge of the damage that can be done by spills, the reports for the Deepwater Horizon are numerous and lengthy, so we will make a brief summary here.
The spill started on April 20, 2010 after an explosion on the Deepwater Horizon, which killed 11 men and injured 17 more. The leak was capped on July 15, 2010, nearly 3 months after the initial gusher erupted. On September 19, 2010 a relief well was completed, and that is when the US government declared the well effectively dead.
The spill created massive environmental damages to both marine and wildlife habitats. The tourism and fishing industries in the Gulf region was also severely affected.
To contain and cleanup the spill, skimmer ships, floating containment booms, anchored barriers, sand-filled barricades along shorelines, and dispersants were used in an attempt to protect hundreds of miles of beaches, wetlands, and estuaries from the spreading oil. Investigating scientists reported immense underwater plumes of dissolved oil not visible at the surface as well as an 80-square-mile “kill zone” that surrounded the blown-out well. In late November 2010, a 4,200 square mile area of the Gulf was closed again to shrimping after tar balls were discovered in local shrimpers’ nets. The total amount of the Louisiana shoreline affected by the oil spill grew from 287 miles (462 km) in July to 320 miles (510 km) in late November of 2010.
In January 2011, an oil spill commissioner reported that tar balls were continuing to wash ashore, oil sheen trails were still seen in the wake of fishing boats, wetlands marsh grass remained fouled and dying, and crude oil lies offshore in deep water and in the fine silts and sands onshore. A research team found oil on the bottom of the seafloor in late February 2011 that did not seem to be degrading. On May 26, 2011, the Louisiana Department of Environmental Quality extended the state of emergency related to the oil spill. By July 9, 2011, roughly 491 miles (790 kilometers) of coastline in Louisiana, Mississippi, Alabama and Florida remained contaminated by BP oil, according to a NOAA spokesperson. A NOAA report released in October 2011 shows dolphins and whales continue to die at twice their normal rate.
The White House oil spill commission released its final report on the causes of the BP Deepwater Horizon oil spill in January 2011. In it they placed the blame on BP and its partners for making a series of cost-cutting decisions and the lack of a system to ensure well safety. They also concluded that the spill was not an isolated incident caused by “rogue industry or government officials”, but that “The root causes are systemic and, absent significant reform in both industry practices and government policies, might well recur”. After its own internal probe, BP admitted that it made mistakes which led to the Gulf of Mexico oil spill. In June 2010 BP set up a $20 billion fund to compensate victims of the oil spill. As of July 2011, the fund has paid $4.7 billion to 198,475 claimants. In all, the fund has nearly 1 million claims and continues to receive thousands of claims each week.
In September 2011, the US government published its final investigative report on the BP Deepwater Horizon spill. In essence, that report states that the main cause was the defective cement job, and Halliburton, BP and Transocean were, in different ways, responsible for the accident.