The United States cannot rule out another oil disaster in its waters, the official who led the response to last year's Gulf of Mexico spill told AFP, as the country marks one year since the tragedy.
"We're never going to be able to prevent an event from happening out there," said retired Coast Guard Admiral Thad Allen, who has worked on oil spills since the 1980s and led the government response to the disaster that began on April 20 last year, when an oil rig moored off the coast of Louisiana exploded.
Eleven men died and several others were injured as fire ripped through the platform, which two days later sank 5,000 feet (1,500 meters) to the bottom of the Gulf of Mexico, causing BP's Macondo well to rupture and start spewing oil into the sea.
BP struggled to cap the ruptured well, which over the course of some three months spewed some 4.9 million barrels of crude into the Gulf of Mexico.
The oil sullied beaches just as the tourist season got under way, coated and killed wildlife and sounded the death knell for the 2010 fishing, shrimping and oyster seasons which are mainstays of the local economy.
"There is still oil being cleaned up," Allen said in an interview with AFP.
"It's much less oil than we had, and it's mostly restricted to marsh areas."
But that, Allen said, poses its own problems, with birds nesting now in the still-tainted roseau cane and grasses off the US southeastern coast.
According to the Natural Resources Defense Council, more than 1,050 miles (1,700 kilometers) of marshland and beaches were oiled in the Gulf oil disaster, and more than 6,000 birds were found dead.
Allen said some 2,000 workers are still working at cleaning up the marshlands at Passe a Loutre, off the coast of Louisiana, and Barataria Bay, a prime shrimping ground that sits at the point where Lafourche bayou opens into the Gulf of Mexico near the Louisiana town of Galliano.
Pass a Loutre is the shrinking patch of wetlands where crude from the BP spill first hit land in May last year.
The US government declared a moratorium on deepwater drilling after the accident and, months later, the Department of the Interior unveiled tough new rules before companies can be granted a drilling permit.
That move, Allen said, would make for safer offshore drilling but was not a guarantee that there would never be another major oil disaster.
"Equipment that can contain oil and cap a well, those are in place now and they are a condition for exploration in the Gulf of Mexico," he said.
"The equipment is in the region and would have to be transported to the site and installed. There would be a time period of 10-12 days, depending where the well is," said Allen.
"It's certainly an improvement over what we had -- which was no containment system," he added. "But we're never going to be able to prevent an event."
Allen retired from the Coast Guard last June but stayed on to lead the government's response to the Gulf spill until the BP well was finally sealed and declared "dead" in September.
"It was pretty clear that this thing would not be done quickly," he said, warning the United States not to repeat key mistakes made after the previous biggest US offshore oil accident, when the Exxon Valdez ran aground off the coast of Alaska in 1989, spilling some 11 million gallons of oil into the sea.
After the Exxon Valdez disaster, "there was a huge amount of research and development into spill response," Allen said, including research into dispersants and in situ burning.
But within two or three years, he said, the research stopped.
"While we focused on a tanker accident after Exxon Valdez and how to avoid that in the future, the oil industry moved off and went deep," Allen said.
"We should not let that happen again," he said.
"We should focus on research and development, innovation and improvements in technology all the time as the industry changes."
Explore further: Germany restricts fracking but doesn't ban it