On Monday, BP released a statement claiming the environment of the northern Gulf of Mexico had returned its “baseline condition” five years after its Deepwater Horizon disaster pumped more than 200 million gallons of oil into the Gulf off Louisiana’s  coast.

But on Tuesday, the U.S. Coast Guard was supervising the ongoing removal of a large oil tar mat on East Grand Terre Island that has yielded more than 25,000 pounds of oil mixed with sand since late February, BP spokesman Jason Ryan confirmed.

BP has been working to clean the beach since Feb. 23, well before their statement was released. However, they didn’t notify the Coast Guard of the mess until March 13, said Seth Johnson, a spokesman for that agency.

Meanwhile, a few miles to the west, two dead adult bottlenose dolphins had washed up on Queen Bess Island, continuing what has been a large die-off of dolphins in Barataria Bay since the oil washed into that critical coastal estuary five years ago.

East Grand Terre, east of Grand Isle on the state’s southeast coast, was among the heavier hit coastal beaches by the BP oil, and it has been the site of ongoing cleanups over the past five years.

Tar mats formed when Deepwater Horizon oil nearing the Louisiana coast became weighed down by the silt from the Mississippi River and sank to the bottom near the shoreline. Quickly covered by sand and sediments from the state’s rapidly-eroding coast, they have frequently been uncovered and washed ashore by stiff southerly winds, especially during tropical storms.

While the most toxic elements of the oil have dissipated, others remain that could pose a health risk to humans and wildlife for decades.

Oil collected in a cleanup is sent to a lab where it can be “finger printed” to determine if it came from the Deepwater Horizon incident. Rya said results on this cleanup have not yet been received.

BP’s report claiming the Gulf has bounced back from the spill cited information gathered by university and industry-sponsored research, but also asserted that findings from the ongoing joint industry-government Natural Resources Damage Assessment supported its claims.

 But state and federal agencies immediately disputed those claims. The National Oceanic and Atmospheric Administration issued a statement saying the damage assessment was still ongoing, while Louisiana’s top coastal official accused BP of cherry-picking the data.

Johnson said the Coast Guard, which has been overseeing and monitoring the continuing Deepwater Horizon cleanup, said the current mat is about 30 meters wide by 1.5 meters long.

In an emailed statement, a  BP spokesman said this cleanup was part of  “a targeted monitoring program established between BP and the state of Louisiana following the end of active cleanup in April 2014.”

He said the “program focuses on remote areas that are not easily accessible and that meet certain criteria that suggest some buried material could potentially remain and become exposed over time.”