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More than eight months after the Deepwater Horizon spill, researchers are still unable to paint an accurate picture on the amount of oil that remains in the Gulf of Mexico. Approximately 200 million gallons of oil flowed into the Gulf during the 84—day well rupture.

After the initial spill, oil on the surface of the water decreased substantially, but pockets of oil have been found by oil—response officials and scientists. According to a government report released in November interventions such as skimming and dispersants removed about 41 percent of the oil while 37 percent of the oil was naturally dispersed, evaporated or dissolved.

Researchers estimate about one-fifth of the oil released from the BP spill, 46 million gallons, remains in the Gulf, but no one knows exactly where it is. Some possibilities include oil remaining on the sea floor, mixing with sediment and sand, being ingested by oil—eating microbes, or collecting along shorelines.

Yet, the Congressional Research Service report admitted that the “estimates used to calculate percentages contain considerable uncertainty.” Accurate estimates are hindered by the Gulf’s complex ecosystem, the resources required to collect data, and varied interpretations of the results.

“Perceptions of the oil’s fate may influence congressional interest and action, with consequences for the affected stakeholders,” the report noted. If it is perceived that more oil remains and poses environmental threats, there could be continued pressure on Gulf industries. “The fraction of crude oil that is water soluble can persist for weeks to years.”

FAST FACT: Federal responders authorized the use of about 1.8 million gallons of chemical dispersants in the Gulf. The impact from chemically dispersed oil is unknown.

Following are other new watchdog reports released by the Government Accountability Office (GAO), various federal Offices of Inspector General (OIG), and other government entities.


  • Royal Dutch Shell received preferential treatment in the awarding of oil shale leases, according to a government audit. Former Secretary of the Interior Gale Norton joined Shell after leaving her government post. Shell submitted and was awarded three leases, while other bidders were only allowed to submit one. (OIG Department of the Interior)


  • A government audit says $4.9 billion for outpatient Medicare services went to 4.5 million recipients in Miami-Dade County, outspending the national average by three times. Questionable billing practices for outpatient therapy were also found. (OIG Department Health and Humans Services)

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