The Coast Guard, BP and the National Oceanic and Atmospheric Administration have worked to assess sheen observed in the Gulf of Mexico in late September. The Coast Guard confirmed the sheen was from the well that failed in 2010 and backed plans for a subsea survey.
U.S. Reps. Ed Markey, D-Mass., and Henry Waxman, D-Calif., members of House energy committees, issued a letter to the Coast Guard requesting more information about sheen observed in the area of the Deepwater Horizon wreck.
Markey and Waxman said they were concerned about lingering environmental effects from the 2010 spill.
"It is imperative that BP take all available actions to mitigate further environmental damage from its oil spill," the letter read.
A review of peer-reviewed research on the spill by the U.S. Geological Survey said "for the most part" oil spilled during the incident was consumed by bacteria.
BP had put a 750-pound cap over an opening in the so-called cofferdam, which was a failed attempt to seal the leak that resulted from an explosion on the Deepwater Horizon rig in 2010.
Notable deaths of 2014 [PHOTOS]