A massive, quickly growing oil slick steered by unpredictable winds and rough seas lapped closer to land Saturday, bearing down on a stunned gulf coastline that had been just beginning to get its swagger back after Hurricane Katrina.

From shrimpers in Mississippi delta fishing towns such as Venice, La., to urban settlers trying to rebuild lives in New Orleans’ Lower 9th Ward, the approaching environmental disaster punctured the upbeat mood with a frightening and uncertain menace.

“People were feeling up for a little while, and people were starting to come back,” said Gilbert Lee, 71, a shrimper in Venice, one of the towns closest to the slick. “But what are they going to come back to now? I’ll tell you, this ain’t nice. It’s pitiful.”

Outside a Lower 9th Ward church where a waving banner said, “We’ve Come This Far by Faith,” residents meeting with Environmental Protection Agency officials were stoic but fearful that the steps they had taken to recover from Katrina would be undone.

It’s a community “that’s not fully recovered,” said Alice Craft-Kerney, a nurse who runs a clinic there. The oil leak “triggers that anxiety of ‘what’s going to happen?’ You remember that from the storm. It’s like, ‘Here we go again.’”

As residents fretted, experts argued over the size of the slick, and federal officials acknowledged that no one knows exactly how much oil is still leaking from the underwater well, which ruptured April 20 during an explosion on a drilling platform 130 miles southeast of New Orleans.

“Any exact estimate of what’s flowing out of those pipes down there is probably impossible,” said Coast Guard Adm. Thad Allen, named Saturday as the point man for the spill. It was Allen whom President George W. Bush turned to after Katrina to take control of the slow and much-criticized response to that disaster.

Allen said the efforts of the federal government, and of BP, which leased the Deepwater Horizon rig, remained focused on stopping the gush from the seabed nearly a mile beneath the surface.

“Estimates are useful, but we are planning far beyond that,” said Allen, a four-star admiral and commandant of the Coast Guard. “That’s why it is so important to stop [it] at the wellhead.”

Already, oil has reached some of the environmentally sensitive islands near the coast. Depending on the weather, Allen said, more significant amounts of oil could hit gulf state shores by Monday or Tuesday.

The Coast Guard has estimated that 200,000 gallons of oil are pouring from the well daily, a figure that would put the total spilled so far at 1.6million gallons. By comparison, the Exxon Valdez tanker disaster in Alaska in 1989 resulted in a spill of 11million gallons.

Most of the assessments of the size of the spill have come from studying satellite images of the Gulf of Mexico, though that analysis doesn’t calculate the thickness of the oil. However, several academics and consultants said Saturday that the size of the slick is larger than previously thought, and may be growing more rapidly.

A tiny nonprofit group, SkyTruth, said Saturday that its analysis of satellite and radar data suggested that more than 11.1million gallons of oil was contained in the slick. John Amos, the group’s president, also estimated the rate of oil leaking at 25,000 barrels a day (more than 1million gallons). There are 42 gallons in a barrel of oil.

Last week, SkyTruth challenged BP’s initial estimate of 1,000 barrels a day, arguing that it was closer to 5,000. The figure was quickly revised.

Allen said it was fruitless to discuss the differences between spill rates. “The continued leakage of anything for an extended period of time is going to cause an extraordinary amount of problems for us,” he said.

BP officials said they were doing all they could to stop the oil gusher. Using robotic submarines, BP is trying to shut the blowout preventer, which would be the quickest fix.

Separately, the company is preparing to drill a hole into the seafloor near the accident site and angle it into the well to seal it off, an effort that would take several months. Also, BP plans to lower 40-foot steel boxes over the gusher in order to contain it. That plan could begin by late this week.

Federal officials have made it clear that they intend to hold BP responsible for costs expected to reach billions of dollars.

Weather continued to hinder efforts to protect the coast Saturday. Winds were kicking up 8- to 10-foot waves, and traditional cleanup techniques such as skimming and using small boats to position booms to corral the fuel were put on hold. The National Weather Service predicted thunderstorms and higher seas Sunday.

President Obama, in a commencement address at the University of Michigan, said the disaster illustrated the importance of government regulation. “Government is what ensures that mines adhere to safety standards and that oil spills are cleaned up by the companies that caused them,” the president said.

The White House said Obama planned to visit the Gulf Coast on Sunday to observe the cleanup efforts.

Administration officials had conducted response drills for Katrina-style disasters during the last year, including a mock oil spill in March. The Interior Department sent a crew and established a command center within four hours of the rig explosion.

Commandant Allen said there were few parallels between the response required for Katrina and the oil rig explosion. “We have a failure of critical infrastructure at 5,000 feet under the ocean,” Allen said. “That’s the only comparison to Katrina, when we had failure of critical infrastructure everywhere on land.”

But for those living in these coastal areas, the feeling of powerlessness in the face of an oil slick that could devastate the fishing industry has echoes of Katrina, and comes at a time when the region was beginning to get back on its feet.

Scars of Katrina remain in fishing towns along coastal Louisiana: empty lots where once-humble homes had stood, unrepaired docks, and the empty metal frames that once were billboards.

But shrimpers who lost their homes and trawling boats are back in business, helped by federal loans and a short-lived side effect of Katrina: The hurricane pushed tons of shrimp and fish inland, which boosted business.

In New Orleans, a couple hours’ drive from the prime fishing grounds, worry is palpable. That city’s culture and self-image is deeply tied not just to the genius of its chefs but to their access to fresh gulf seafood.

The city had begun feeling it had “turned a corner, after years and years of hard work,” said D. Eric Bookhardt, a New Orleans art critic and culture writer. Now, “people are just very apprehensive — not because of any immediate threat, but because [it] is going to require so much extraordinarily hard work to overcome.”

Those raw feelings were on display in the Lower 9th Ward at a community meeting Saturday with EPA Administrator Lisa P. Jackson. Some residents said they wanted to make certain that the government would “not let BP off the hook,” as one put it. Others were leery of the government.

“We are veterans of disaster,” said Ronald Lewis, who runs the House of Dance and Feathers museum. “We survived Katrina. Mentally, we’ll be prepared.” But, he added, “our fate was in the hands of the government, and the government failed us on all kinds of levels after Katrina.”

“I know everyone’s mad,” Jackson told the group. She assured them that BP would be responsible for the bill, adding, “I’m still praying they will be able to cut off the source.”

In the French Quarter, restaurant owners tried to reassure their staff and patrons that, after Katrina, they could survive anything.

Steve Pettus, one of the owners of Bourbon House Seafood, said New Orleans had been on a high with the Saints’ Super Bowl victory and one of the country’s lowest unemployment rates.

“We’ve been to the bottom and we didn’t like it, and we’re not going to be there again,” he said.

Just to be safe, though, Pettus had taken precautions. He bought a four-week supply of shrimp.

richard.fausset@latimes.com

ashley.powers@latimes.com

jim.tankersley@latimes.com

Staff writers Julie Cart and Scott Kraft contributed to this report.