NEW ORLEANS — It could take hours or it could take months to stop a 42,000-gallon-a-day oil leak polluting the Gulf of Mexico at the site of a wrecked drilling platform.
Whether the environmental threat grows many times larger depends on whether the oil company can turn the well completely off.
Crews are using robot submarines to activate valves at the well head in hopes of cutting off the leak, which threatens the Gulf Coast's ecosystem of shrimp, fish, birds and coral. If the effort fails, they'll have to start drilling again.
The submarine work will take 24 to 36 hours, Doug Suttles, chief operating officer for BP Exploration and Production, said Sunday.
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"I should emphasize this is a highly complex operation being performed at 5,000 feet below the surface and it may not be successful," he said.
Oil continued to leak nearly a mile underwater Sunday at the site where the Deepwater Horizon rig exploded on Tuesday. Eleven workers are missing and presumed dead.
For the second consecutive day, high waves prevented boats and equipment from going out to clean the spill. Airplanes sprayed chemicals to break up the oil.
The spill initially appeared to be easily manageable after the oil rig sank Thursday about 50 miles off the Louisiana coast, but it has turned into a more serious environmental problem. Officials on Saturday discovered the leak, which is spewing as much as 1,000 barrels — or 42,000 gallons — of oil each day.
The oil spill has been growing — officials said the oily sheen on the surface of the gulf covered about 600 square miles Sunday. The environmental damage would be especially serious if it reaches land.
The spill was still about 70 miles from the mainland, but only about 30 miles from an important chain of barrier islands known as the Chandeleurs.
The islands, part of a national wildlife refuge, are a nesting ground for pelicans and other sea birds. They have been under serious threat since Hurricane Katrina washed out much of the sand there.
The spill so far appears to be small relative to some major oil accidents. The Exxon Valdez spilled 11 million gallons in Alaska's Prince William Sound in 1989 — the worst oil spill in U.S. history.
"It has the potential to be pretty serious, but at 1,000 barrels a day, if it comes to the surface they'll probably be able to contain it and vacuum it up," said James Cowan, an oceanography and coastal sciences professor at Louisiana State University.
The company is planning to collect leaking oil on the ocean bottom by lowering a large dome to capture the oil and using pipes and hoses to pump it into a vessel on the surface, said Suttles, the BP executive.