It appears there is a rig other than Deepwater Horizon that has been leaking oil into the Gulf of Mexico since April.
The second possible spill is “small but persistent” and was discovered by SkyTruth, a nonprofit group that tracks environmental disasters with satellite photos.
Images analyzed by SkyTruth show a small slick developing near the Mississippi Delta in late April, with the much larger slick from Deepwater horizon approaching it over time.
Kate Shepard of Mother Jones explains how the smaller spill could have gone undected:
Right now, oil companies are required by law to report any spills to the National Response Center, Coast Guard or Environmental Protection Agency if there is a “visible sheen.” Oil companies report spilling roughly 1.3 million gallons of oil into US waterways in an average year. But that figure is largely reliant on self-reporting; the government trusts that operators are following the law and reporting all of the spills, Amos says. Coast Guard 1st Class Petty Officer Zach Zubricki told Mother Jones that they do not know of any other spills in the Gulf at this point in time. “I’m only aware of one leak,” said Zubricki. He noted that it’s possible the sheen is related to the major spill from the Deepwater Horizon, since “you get oil everywhere” with a leak of that size.