NEW ORLEANS, Louisiana (AFP) – A giant oil slick threatened Thursday to pollute the fragile wetlands of Louisiana, as officials warned that toxic crude was pouring from a ruptured well into the Gulf of Mexico five times faster than previously estimated.
Louisiana Governor Bobby Jindal called on the federal government for emergency help to stave off an environmental disaster after a sudden change in the wind direction turned week-long response efforts on their head.
The dangerous slick early Thursday reportedly was just 16 miles (25 kilometers) from shore, but hundreds of miles of coastline were under threat in the states of Louisiana, Mississippi, Alabama, and Florida.
In another major blow, the US government's National Oceanic and Atmospheric Administration (NOAA) announced that more than 200,000 gallons of oil a day were now thought to be spewing into the Gulf from the debris of the Deepwater Horizon rig, which sank last week following a deadly explosion.
British energy giant BP, which leases the rig and has been leading the response to the disaster along with the US Coast Guard, acknowledged a newly-discovered leak but said it believed the flow of oil was unchanged at 1,000 barrels, or 42,000 gallons, a day.
The new leak was detected "upstream," on the riser pipe which had connected the well to the rig before the accident, and therefore not a source of additional oil emanating from the well, according to BP.
Jindal said NOAA reports suggested a portion of the slick, which has a 600-mile (965-kilometer) circumference, had broken off and could register a direct hit on coastal nature reserves on Thursday due to strong winds.
"At this time, the Pass-A-Loutre Wildlife Management Area is expected to see the first impact of the oil spill," he said, adding that he had spoken to US Homeland Security chief Janet Napolitano to seek additional assistance.
More than 20 miles of booms, inflatable barriers that float on the sea surface and are intended to contain the spill, have been placed along the Louisiana coast but Jindal said more were needed.
Crews began a controlled "trial" burn Wednesday of the thickest parts of the slick but a change in the wind direction threatened to undo their good work and become a far more important factor.
Two skimming vessels swept dense concentrations of oil in the center of the slick into a 500-foot (150-meter) fire-resistant boom.
It was set alight in a zone roughly 50 miles south of the mouth of the Mississippi river in what BP described as a "successful" burn operation.
Similar efforts on past spills have burnt off between 50 and 90 percent of oil captured and crews plan several more burns in the coming days.
Nevertheless, Charlie Henry, a scientific support coordinator from NOAA, said there was a "high risk" that strong winds from the southeast would push emulsified oil and "tar balls" into the Mississippi delta area by Friday night.
If large quantities of crude drift into Louisiana's marshy wetlands, mopping it up would be next to impossible.
It would be disastrous for natural parks full of waterfowl and rare wildlife and could also imperil the state's 2.4-billion-dollar-a-year fisheries industry, which produces a significant portion of US seafood.
The Deepwater Horizon platform sank April 22, two days after a huge explosion that killed 11 workers.
The accident has not disrupted offshore energy operations in the Gulf, which account for 30 percent of all US oil production and 11 percent of domestic gas production.
BP, which leased the semi-submersible rig from Houston-based contractor Transocean, has been operating four robotic submarines to try and cap the ruptured well on the seabed some 5,000 feet (1,500 meters) below the surface.