HOUSTON (Reuters) - An oil sheen spotted on the Gulf of Mexico near the site of the sunken Deepwater Horizon rig matches samples from BP Plc's ill-fated Macondo well, the U.S. Coast Guard said.
BP reported a sheen on September 16 in block 252 of the Mississippi Canyon, about 50 miles off the Louisiana coast. Test samples indicate that "the sheen correlates to oil that originated from BP's Macondo Well", the Coast Guard said in a statement late on Wednesday.
Swiss-based Transocean Ltd owned the Deepwater Horizon drilling rig and London-based BP was the operator of the Macondo well, which ruptured on April 20, 2010, killing 11 workers and unleashing the worst U.S. offshore oil spill. BP and Transocean had no immediate comment on the sheen.
The well spewed 4.9 million barrels of oil into the Gulf of Mexico for 87 straight days, unleashing a torrent of oil that fouled the shorelines of four Gulf Coast states and eclipsed the 1989 Exxon Valdez spill in Alaska in severity. The well was capped with cement on September 19, 2010, which U.S. officials said had "killed" the leaking well for good.
According to the Coast Guard, the sheen likely comes from wreckage on the seafloor, not the well itself.
"The exact source of the sheen is uncertain at this time, but could be residual oil associated with wreckage and/or debris left on the seabed from the Deepwater Horizon incident in 2010," the Coast Guard said. "The sheen is not feasible to recover and does not pose a risk to the shoreline."
The Coast Guard notified BP and Transocean that "either party or both may be held accountable for any cost associated with further assessments or operations related to this sheen".
A U.S. lawmaker said the U.S. government should require BP to utilize remotely operated undersea vehicles to survey the ocean floor around the site.
"BP must do everything in its power to ensure this well does not rupture or leak, and they should be held responsible if it does," said U.S. Representative Edward Markey, a Massachusetts Democrat. "BP still has billions to pay to the people of the Gulf and the U.S. government, but the Gulf region also deserves the peace of mind that this well is dead once and for all."
(Reporting by Chris Baltimore; Editing by Dale Hudson)