Venice, Louisiana (CNN) -- Gulf Coast residents smelled a calamity Friday as the oil slick caused by the Deepwater Horizon rig explosion floated toward Louisiana.

The Coast Guard was conducting a flyover Friday morning to see if oil had reached the state's coastline as federal, state and local officials scrambled to avert a natural disaster threatening to surpass the Exxon Valdez disaster 20 years ago in Alaska.

People along the Louisiana coast caught a whiff of the wafting smell of oil and feared an environmental nightmare of greater scope.

"There's certainly immense potential consequences," LuAnn White, director of the Tulane Center for Applied Environmental Public Health said Friday.

"This is a disaster," said Dean Blanchard, who runs a wholesale seafood business in the region. "We definitely need some help."

Officials were scrambling to keep the oil spill from damaging sensitive coastal wetlands along the Gulf of Mexico.

President Obama is sending three top officials to to Louisiana on Friday to inspect efforts to contain the 120-mile oil slick creeping toward the mouth of the Mississippi River.

Homeland Security Secretary Janet Napolitano, Interior Secretary Ken Salazar and Environmental Protection Agency Administrator Lisa Jackson will travel to Louisiana on Friday, the White House said.

The three will conduct an aerial tour of the area and discuss cleanup efforts with federal, state and local officials. They also will meet with officials from oil company BP, which owns the ruptured well where oil continues to leak.

State and federal agencies have strung miles of floating booms -- inflatable or foam barriers -- around the leading edge of the shoreline to contain the spill. Nearly 175,000 feet -- about 33 miles -- of floating booms have been deployed in the region, with about a half-million more feet expected, federal officials said.

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A handful of federal agencies have recovered more than 18,000 barrels of an oil-water mix and had deployed nearly 100,000 gallons of dispersant, which breaks up oil, as of Thursday evening, according to the Department of Homeland Security.

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Efforts to shut down the well have failed so far, and more complicated plans may take weeks, officials said.

Louisiana Gov. Bobby Jindal on Thursday declared a state of emergency ahead of the oil slick's arrival, warning that it covered as much as 600 square miles of water.

Ten wildlife refuges in Mississippi and Louisiana are in the oil's likely path, with the Pass-a-Loutre Wildlife Management Area at the tip of the Mississippi River likely to be the first affected, Jindal said.

Wildlife conservation groups have said the oil could be a disaster for Louisiana, Mississippi, Alabama and Florida coastal areas.

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The latest forecast from the National Oceanic and Atmospheric Administration showed the leading edges of the slick reaching the Mississippi and Alabama coasts over the weekend and stretching as far east as Pensacola, Florida, by Monday.

The oil well was ripped open by an April 20 explosion that sunk the drill rig Deepwater Horizon, leading to the presumed deaths of 11 missing men.

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The Coast Guard on Wednesday raised its estimate of the amount of oil the damaged well was pouring into the Gulf to 210,000 gallons a day -- about 5,000 barrels.

An effort to burn off part of the oil slick Wednesday destroyed about 100 barrels, said Doug Suttles, chief operating officer of BP. But the technique "clearly worked," and larger burns are planned when weather conditions make them possible.

"We believe we can now scale that up and burn between 500 and 1,000 barrels at a time," Suttles said.

The well is leaking from three points, BP said. Under the 1990 Oil Pollution Act, passed a year after the Exxon Valdez oil spill in Alaska, the company is required to foot the bill for the cleanup.