An oil spill that threatened to eclipse even the infamous Exxon Valdez disaster spread out of control with a faint sheen washing ashore along the Gulf Coast Thursday night as fishermen rushed to scoop up shrimp and crews spread floating barriers around marshes.
The spill was bigger than imagined five times more than first estimated and closer. Faint fingers of oily sheen were reaching the Mississippi River delta, lapping the Louisiana shoreline in long, thin lines.
"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."
(Scroll down to view a map of approximate locations where the oil spill has spread and where it is expected to spread Thursday)
Officials say they will do everything they can to not disrupt river traffic.
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BP operated the rig that exploded and sank 50 miles offshore last week and is directing the cleanup and trying to stop the leak from a blown-out underwater well.
The oil spill threatens Louisiana's barrier islands - a buffer against hurricanes - its marshlands and , including whales, dolphins and the brown pelican - the state bird - CBS News Correspondent Mark Strassmann reports from Empire, La.
As the oil nears shore, environmental experts say the damage , the worst oil spill in U.S. history and one of the worst environmental disasters in decades.
It remains unclear how much oil will flow into the Gulf before the flow can be cut off. The teams of state, federal and company officials charged with the cleanup have tried unsuccessfully to activate an underwater cutoff valve and now say they plan to dig a relief well half a mile away - a process that could take weeks or months. (BP, the company that leased the sunken rig, is currently leading the cleanup effort but has asked the military for assistance.)
According to the latest estimates, oil is flowing into the Gulf at the rate of 5,000 barrels - or 210,000 gallons - a day. At that rate, it would take nearly two months to equal the 11 million gallons unleashed by the Valdez, a 1,000-foot tanker that breached after crashing into a reef in Alaska's Prince William Sound.
But experts say that even if the current spill doesn't match the Valdez in terms of pure numbers, it could be more damaging because the marshlands of the Mississippi delta are home to numerous species of threatened and endangered birds and other animals.
"It's quite possible this will end up being worse than the Valdez in terms of environmental impact since it seems like BP will be unable to cap the spill for months. In terms of total quantity of oil released, it seems this will probably fall short of Exxon Valdez. But because of the habitat, the environmental impact will be worse," John Hocevar, oceans campaign director for Greenpeace USA, told MSNBC Thursday.
From Texas to Louisiana, environmentalists are preparing for the worst. Volunteers are already being drafted to wash oil off animals.
Louisiana shrimp season was opened early Thursday to of the catch. Fishermen are worried.
"This is the time of year they all come in," one fisherman said. "With the oil slick out there, it can kill all the shrimp that's coming in, so we're worried serious about this. It could be devastating to our industry."
Some experts say the oil rig explosion should never have led to a disaster of this magnitude, and they're blaming the federal government for lax safety standards, CBS News Correspondent Ben Tracy reports.
Sen. Bill Nelson, D-Fla., sent President Obama a letter Thursday reminding him that in 2000 the Interior Department insisted "oil companies have 'reliable backup systems' in the event of a rig blowout."
By 2003, the plan was scrapped.
"This could be one of the world's greatest nightmare scenarios of an oil gusher," Nelson said.
The backup systems are supposed to act when an oil rig fails and starts leaking. Then, a valve deep under the water where the drill pipe meets the ocean floor is supposed to choke off the flow of oil. In the case of BP's platform, either the valve wasn't activated or didn't work, possibly because of the explosion.
But there is another line of defense this oil platform did not have, a so-called acoustic switch. It can be activated by remote control sending acoustic pulses through the water to trigger the blowout preventer even if the rig is damaged or evacuated.
Acoustic switches are used in Norway and Brazil after those oil producing countries suffered spills. The U.S. considered requiring them, but drilling companies questioned the $500,000 cost and whether the devices even work.
"There are multiple safety devices which should have brought the flow to a cease when the event happened, so we shouldn't actually assume that this acoustic switch would have also caused it to stop," BP PLC chief operating officer Doug Suttles said.
The spill in the Gulf comes at a time when Mr. Obama has called for a major expansion of offshore drilling. Nelson said not so fast Thursday and proposed a bill to temporarily halt the president's plans. The administration says .
Louisiana Gov. Bobby Jindal announced that BP PLC has agreed to allow local fishermen to assist in the expected cleanup. Under the agreement, shrimpers and fishermen could be contracted by BP to help.
Jindal's declaration says at least 10 wildlife management areas and refuges in his state and neighboring Mississippi are in the oil plume's path. It also notes that billions of dollars have been invested in coastal restoration projects that may be at risk.
Suttles says the company is hoping to try the unusual technique of using chemicals to break up the oil under water.
The company has been reviewing research on the technique which has been used before, but never at these depths. The well is almost a mile underwater.
Suttles says the company is bringing the chemical to the site of massive spill and already has a giant reel of tubing in place. If approved, work could start Thursday night.
U.S. Coast Guard Rear Adm. Mary Landry called it "a novel, absolutely novel idea."
The Obama administration pledged an all-out response Thursday to the massive oil spill, dispatching top officials to the region to help coordinate defenses against the potential environmental disaster.
"We are being very aggressive and we are prepared for the worst case," Coast Guard Rear Adm. Sally Brice-O'Hara said at the White House.
Mr. Obama, speaking at an event for the 2010 National Teacher of the Year, said he had been receiving frequent briefings on the situation and that he is prepared to use the resources of the Department of Defense if necessary to deal with the oil spill.
Suttles said at a news conference on Thursday that the company has asked the Department of Defense if they can help with better underwater equipment than is available commercially. The company has specifically asked for imaging techniques and remote operating vehicles, he said.
Mr. Obama said SWAT teams were being dispatched to the Gulf to investigate oil rigs and said his administration is now working to determine the cause of the disaster.
The president promised to deploy "every single available resource" to the area and ordered his disaster and environmental leaders to go. The Navy is and seven skimming systems, and using its bases in the region as staging areas for the operation.
Federal officials announced inspections would begin immediately of all oil rigs in the Gulf and subpoena powers would be used in the gathering investigation. But the priority was to support the oil company BP PLC in employing booms, skimmers, chemical dispersants and controlled burns to fight the oil surging from the seabed.
The administration rejected suggestions that the federal government was slow to act in dealing with the spill and expressed frustration with BP's inability to seal the ruptured well head. The government approved the start of drilling for a relief well and was considering approving a second one as industry and government officials worked on multiple fronts to contain the slick.
Homeland Security Secretary Janet Napolitano, Interior Secretary Ken Salazar and Lisa Jackson, the administrator of the Environmental Protection Agency are explected to visit the Gulf Coast Friday, the same day the massive oil spill is expected to hit U.S. coastline.
"This is a spill of national significance," Napolitano said during a briefing for reporters at the White House.
Classifying the spill with the phrase "national significance" allows the government to tap funds from other areas of the country's coastline to pay for efforts to clean up and monitor the spill, Napolitano said.
Napolitano pledged her department will make sure that BP will reimburse the government for any taxpayer dollars spent on the clean up.
David Hayes, a deputy secretary of the Interior, told reporters that Salazar has ordered immediate inspections of all deep water oil platforms in Gulf.
"That inspection operation is underway as we speak," Hayes said.
Salazar wasn't at the briefing because he was already at a command center in Houston, Hayes said.
Napolitano said the Homeland Security and Interior departments are conducting a joint investigation into what caused the explosion on the rig.
Brice-O'Hara described of the oil spill as "very successful," but she said sea and wind conditions won't allow another such burn to be conducted Thursday.
Jackson said the EPA will assist the Coast Guard, which is the lead agency in matters involving the sea and the country's coastline. However, the EPA will monitor air conditions using aircraft and fixed monitors, she said. The EPA will release air quality data within the next few days, she said.
President Obama spoke Thursday with five Gulf state governors from Florida to Texas.
Michael Sole, chief of Florida's Environmental Protection Department, said governments are digging in for a long struggle and it's too soon to know what his state will need from Washington.
"It's only been a week now," he said. "It may be two or three months before they can stop the discharge. The magnitude of this thing gives me concerns as to whether they're going to be able to address the entire coast of the Gulf of Mexico."
So far, he said, the federal government has acted aggressively and cooperatively.
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