BP said an inspection of the Macondo well, the site of the 2010 spill in the Gulf of Mexico, found it isn't leaking. Sheen reported in the area last month, the company said, is from a so-called cofferdam, an 86-ton steel container used in the first attempt to control the leak in May 2010.
"A mixture of oil and slushy methane hydrates was trapped inside the cofferdam during the response," said BP in a statement.
Rep. Ed Markey, D-Mass., ranking member of the Natural Resources Committee, called on BP to release underwater video taken of the site in order to allay public concerns the Macondo well wasn't leaking.
"In addition, BP should seek to recover all oil trapped inside the failed containment dome or any other debris that remains on the sea floor in order to prevent even more oil from spilling into the environment," he said in a statement.
BP said this is the third time it's been able to confirm the Macondo well isn't leaking. The Coast Guard, meanwhile, said the sheen didn't pose a risk to the U.S. shoreline.