A year after one of the largest oil spills in history threatened the coastal ecosystem and economy of U.S. states along the Gulf of Mexico, drilling there has resumed.

Washington has issued a handful of permits for oil exploration in the Gulf over the last few months, and some Republicans in Congress are pushing for more.

"The fact of the matter is we have a tremendous abundance of fossil fuels that we need to utilize," said Representative Doc Hastings, a Republican from Washington state who is shepherding three bills through the House that would open the west and east coasts to drilling after a 30-year ban and speed the permit process elsewhere.

The administration of President Barack Obama issued a moratorium on new offshore oil drilling in the wake of last year's disaster, but lifted it for the Gulf of Mexico in October.

In Louisiana, where coastal areas were most vulnerable after the Deepwater Horizon offshore oil rig exploded April 20, 2010, politicians from both parties support more drilling.

Louisiana Senator Mary Landrieu, a Democrat, railed against the moratorium and wants the permit process for new rigs simplified so jobs won't be lost.

Republican Representative John Fleming of Louisiana says the U.S. needs the oil.

"We have domestic energy constipation. We need a good laxative to get domestic production going again," he said.

800 million litres leaked

Naturally, environmentalists aren't so keen. After the Deepwater Horizon rig blew up 80 kilometres off the Louisiana coast, killing 11 workers, it sank to the bottom and the wellhead began gushing 800 million litres of petroleum into a marine ecosystem teeming with life.

An underwater video camera shows oil gushing from the blown-out well's riser pipe last June. (BP/Associated Press)

At first, government and business pegged the flow rate at a modest 1,000 barrels a day, but within a week the well's operator BP was forced to concede that much more oil was spewing — up to 50,000 barrels a day at its peak, scientists estimated.

When the leaking well was finally plugged 3½ months later, thousands of mammals, birds and reptiles had died in the coastal hydrocarbon swell, as well as untold numbers of fish. Oil affected shrimp and oyster beds. The Louisiana seafood industry, subject to fishing bans that have since been revoked and, perhaps worse, a major image problem, has never recovered.

"The only way to prevent human, economic and environmental tragedies like the BP deepwater disaster," said Phil Radford, executive director of Greenpeace USA, "is to re-enact the moratorium on offshore drilling and to replace dirty dangerous fuels with clean energy."

Anniversary marked

Solemn ceremonies marked the one-year anniversary of the disaster Wednesday and underscored the delicate healing that is only now taking shape.

Relatives flew over Gulf of Mexico waters where the oil rig workers died and residents gathered in quiet prayer vigils onshore.

Oil still occasionally rolls up on beaches in the form of tar balls, and fishermen face an uncertain future.

The Deepwater Horizon oil rig blazes on April 21, 2010, after an explosion caused by a bubble of methane gas. The rig sank the next day. (Gerald Herbert/Associated Press)

But traffic jams on the narrow coastal roads of Alabama, crowded seafood restaurants in Florida and families vacationing along the Louisiana coast attest to the fact that familiar routines are returning, albeit slowly.

Although life is getting back to normal, many questions linger: Will the fishing industry recover? Will the environment bounce back completely? Will an oil-hungry public ever accept more deepwater drilling?

"It seems like it is all gone," said Tyler Priest, an oil historian at the University of Houston. "People have turned their attention elsewhere. But it will play out like Exxon Valdez did. There will be 20 years of litigation."

An administrator has handed out $3.8 billion from a $20-billion US claims fund set up by BP. The number of cleanup workers went from 48,000 at the height of the spill to 2,000 today.

Most scientists agree the effects "were not as severe as many had predicted," said Christopher D'Elia, dean at the School of the Coast and Environment at Louisiana State University. "People had said this was an ecological Armageddon, and that did not come to pass."

A brown pelican tries to raise its wings after being drenched in oil along the Louisiana coast last June. (Charlie Riedel/Associated Press)

Still, biologists are concerned about the spill's long-term impact on marine life. The Deepwater Horizon leak was nearly 20 times as big as the 1989 Exxon Valdez spill off Alaska.

"There are these cascading effects," D'Elia said. "It could be accumulation of toxins in the food chain, or changes in the food web. Some species might dominate."

Accumulated oil is believed to lie on the bottom of the Gulf, and it still shows up as a thick, gooey black crust along Louisiana's marshy shoreline. Scientists have begun to notice that the land in many places is eroding.

'You need the industry to continue'

A presidential commission and an internal BP report concluded that the disaster was caused by a cascade of technical and managerial failures, including a faulty cementing job. A testing firm hired by the government concluded that the key device used for preventing blowouts failed because of a design problem that prevented it from cutting through pipe to stop the flow.

Fresh revelations from a BP engineer's email exchanges with his wife also highlight missteps made on the ill-fated rig before the explosion.

Oil from the spill floats into Bay Jimmy on the Louisiana coast. Crews found nearly 7,000 dead animals, including birds, reptiles and more than 400 dolphins, on the U.S. Gulf Coast in the months following the disaster. (Gerald Herbert/Associated Press)

In email to his wife on March 11, 2010, Brian Morel said his team aboard the rig was "out of control."

"I can't take it, so I am staying away from the issues today," he wrote.

For the most part, the damage was eventually contained.

"If you come out and see the progress, you'd think so too," said Mike Brewer, an oil spill response supervisor.

Brewer, who has spent 25 years cleaning up spills in Louisiana, said this spill was the Big One that he always feared. But was it the last spill ever?

"You expect sooner or later it will happen. And sooner or later, I believe it will happen again," he said. "You need the industry to continue to produce, to continue to drill, and you just need more cautionary measures. You just can't cut corners."

With files from The Associated Press