Reporting from Atlanta and New Orleans — With the BP oil well sealed for 11 days, federal officials said Monday that much of the surface oil had broken up into thousands of small patches that were proving difficult to hunt down and clean up.
Coast Guard Rear Adm. Paul Zukunft, the federal on-scene coordinator, said the development was "actually a good news story pertaining to this oil spill."
Zukunft said at a news conference that he spent five hours Sunday flying over the water looking for oil and found only one "skimmable amount" off Louisiana.
The capped well, aggressive cleanup and dissipation of the light, sweet crude have resulted in "very, very moderate amounts, and less concentrated amounts of oil on the surface," he said.
The National Oceanic and Atmospheric Administration estimated that crews would continue to see surface oil for four weeks, Zukunft said. But he added that the estimate might be too conservative. Crews have not applied dispersants for more than a week, he said, because the oil has weathered to a point at which using them is "inefficient and ineffective."
Tempering the good news, however, are concerns about the effect of massive plumes of oil that had been discovered beneath the ocean surface since the April 20 explosion of the Deepwater Horizon rig. In late May and early June, researchers from the University of Georgia found one of these plumes to be about 15 miles long, 5 miles wide and 300 feet thick, at depths of 2,300 to 4,200 feet.
David Pettit, an attorney with the Natural Resources Defense Council, said that with less oil on the water's surface, "the chances of a big slug of oil making its way to the beaches and wetlands and the like is reduced.
"But what we don't know is what's going to happen to these enormous undersea plumes.... Will they move with the currents? Will they wash up some day? Will it all sink to the bottom and smother the sea life down there? We don't know."
In a separate news conference Monday, retired Adm. Thad Allen, the federal spill response chief, said that although the 794 skimmers would keep hunting for small surface-oil patches, crews would also focus on "the oil we can't see," with the help of NOAA. The agency is conducting what he called an "aggregate MRI" of the water column in an attempt to find the undersea oil.
"We're going to have tar balls and other kinds of impacts that are going to go on for a long, long time," said Allen, adding, "There's still a lot of oil that's unaccounted for."
Patches of oil are still washing ashore, scattered along Louisiana's southern and southeastern edges, specifically near the Chandeleur Islands, Breton Sound and the Mississippi Delta, and along shores extending westward, including Barataria Bay, Terrebonne Bay and Caillou Bay.
An ocean with less oil to skim has also raised questions about employment for the many fishermen who signed up with BP to clean the Gulf of Mexico after their fishing areas were closed.
Zukunft said some of the skimming boats might be redeployed soon to trawl the ocean for tar balls, much as they once did for fish.
The oil stopped flowing into the gulf after BP affixed a cap to the well July 15. But federal officials and BP say the well still needs to be permanently plugged by a relief well, which will jam it with mud and concrete.
Allen on Monday gave an updated and more detailed timeline of that plan. He said that a preliminary "static kill" — which involves pumping mud in from the top — would probably take place Aug. 2, and that the relief well could penetrate the well five days later.