An oil spill that threatened to eclipse even the Exxon Valdez disaster spread out of control and drifted inexorably toward the Gulf Coast as fishermen rushed to scoop up shrimp and crews spread floating barriers around marshes.
The spill was both bigger and closer than imagined -- five times larger than first estimated, with the leading edge just 3 miles from the Louisiana shore.
"It is of grave concern," David Kennedy of the National Oceanic and Atmospheric Administration, told The Associated Press.
"I am frightened. This is a very, very big thing. And the efforts that are going to be required to do anything about it, especially if it continues on, are just mind-boggling."
The oil slick could become the nation's worst environmental disaster in decades, threatening hundreds of species of fish, birds and other wildlife along the Gulf Coast, one of the world's richest seafood grounds, teeming with shrimp, oysters and other marine life.
Louisiana Gov. Bobby Jindal declared a state of emergency Thursday, and President Obama pledged his administration will use "every single resource at our disposal."
Jindal made the declaration shortly after Homeland Security Secretary Janet Napolitano called the disaster a "spill of national significance."
The Coast Guard worked with BP, which operated the oil rig that exploded and sank last week, to deploy floating booms, skimmers and chemical dispersants, and set controlled fires to burn the oil off the water's surface. Obama said the response could include the Defense Department.
Thursday's order allows the state to free up resources to begin preparing for the oil to reach the shore.
Napolitano, Interior Secretary Ken Salazar and environmental protection administrator Lisa Jackson will travel Friday to the Gulf of Mexico to oversee efforts to contain the spill. White House press secretary Robert Gibbs said the administration also may send military ships and personnel to help control damage from the spill.
British oil giant BP confirmed Thursday that up to 5,000 barrels, or 200,000 gallons, of oil a day are spilling from the site of the deadly oil rig explosion.
At that rate, the spill could easily eclipse the worst oil spill in U.S. history -- the 11 million gallons that leaked from the grounded tanker Exxon Valdez in Alaska's Prince William Sound in 1989 -- in the three months it could take to drill a relief well and plug the gushing well 5,000 feet underwater on the seafloor. Ultimately, the spill could grow much larger than the Valdez because Gulf of Mexico wells typically hold many times more oil than a single tanker.
Jackie Savitz, a toxicology scientist with the environmental group Oceani, says that at the current flow rate, the spill will reach the 11 million gallon mark of the Exxon Valdez spill in 50 days. The Gulf holds several endangered and threatened species, including four species of endangered sea turtle, in addition to dolphins, porpoises and whales.
"This is one of only two spawning areas for bluefin tuna in the world," Savitz said. "If larvae are exposed, there's a good chance they won't survive or their survival will be reduced because of the oil spill."
Doug Suttles, the oil company's chief operating officer, told NBC's Today show that oil is bubbling up from the ocean bottom at a rate of 1,000 to 5,000 barrels a day. He said the company would welcome help from the U.S. Defense Department and other agencies in containing the slick.
"We'll take help from anyone," Suttles said.
As the slick has grown, so have potential cleanup costs.
"As the president and the law have made clear, BP is the responsible party" for costs, Napolitano said.
A third leak was discovered in the blown-out well, which is about a mile under water. Coast Guard Rear Adm. Mary Landry said it may be time for government agencies to offer up "technologies that may surpass abilities of the private sector" to get the slick under control.
Landry said more than 5,000 barrels a day of sweet crude are discharging into the gulf, not the 1,000 barrels officials had estimated for days since the Deepwater Horizon drilling rig exploded and sank 50 miles off the Louisiana Coast. The new oil spill estimate came from the federal National Oceanic Atmospheric Administration.
Initially, Suttles said he did not believe the amount of oil spilling into the water was greater than earlier estimates. But on Thursday, he acknowledged that the leak may be as high as the government is estimating.
"Using the satellite imagery and our overflights, we can now say it looks like it's more than a thousand. It's a range" of up to 5,000, he said.
BP spokesman John Curry said it doesn't really matter what the numbers are, the slick is what it is, and corralling it is the important thing.
"We can't physically go down and put a meter on the leak to measure how much is flowing, so it's all a guess, it's all an estimate," he said. "And the different estimates don't change our response. I mean, they all are within the general range of uncertainty, and we're not going to stop until we get this done."
Eleven workers are missing and presumed dead, and more than 100 escaped the blast, the cause of which has not been determined.
Industry officials say replacing the Deepwater Horizon, owned by Transocean Ltd. and operated by BP, would cost up to $700 million. BP has said its costs for containing the spill are running at $6 million a day. The company said it will spend $100 million to drill the relief well. The Coast Guard has not yet reported its expenses.
Material from NPR's Wade Goodwyn and The Associated Press was used in this report.
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