On a cold March night 25 years ago, the supertanker Exxon Valdez struck a reef off the coast of Alaska, spilling 11 million gallons of crude oil into the sea.

Images of oil-soaked birds and fouled beaches horrified the United States, leading to tighter regulation and greater environmental consciousness.

The Exxon Valdez grounding on March 24, 1989, has since been replaced by the 2010 Deepwater Horizon disaster in the Gulf of Mexico as the worst oil spill in US history.

Yet local communities in the formerly pristine Prince William Sound are suffering.

"There is a lot of bitterness still to this day," Steve Rothchild from the Prince William Sound Regional Citizens' Advisory Council told AFP.

The council was created after the spill to oversee oil transportation and provide a voice for the communities that were struggling after the collapse of the fishing industry.

Rothchild complains that Exxon did not fulfill its promise to "make the people whole."

"When the court case was finally adjudicated, the people got pennies on the dollar they really deserved," he said, using an expression meaning they were short-changed.

- Dwindling salmon population -

The oil giant, which changed its name to Exxon Mobile after a merger in 1999, was originally ordered to pay $5 billion to more than 32,000 Alaska Natives, landowners and commercial fishermen.

After a lengthy legal battle, the Supreme Court limited the punitive damages in June 2008 to about $500 million.

Exxon also spent more than $2 billion on the cleanup effort and reached a settlement with the US government that included $900 million in payments, a $25 million criminal fine and $100 million in restitution.

Angela Day's husband was a fisherman in the small port town of Cordova before the dwindling salmon and herring populations forced him out of business.

"He's been fishing there for about 30 years, he grew up in the fishing industry and had two vessels at the time of the oil spill," Day said.

"It was really hard on the community," she recalled, adding that the disruption of the local economy led to "more drinking, some suicides, more divorces."

Exxon hired some fishermen to help the cleanup effort but many lost their livelihoods as the value of their boats and fishing permits plummeted.

"My husband did not even get back a quarter of what his two fishing vessels were worth at the time," said Day, author of the recently published account "Red Light to Starboard: Recalling the Exxon Valdez Disaster."

- 'Got people thinking' -

During that fateful March night in 1989, the captain Joseph Hazelwood diverted the Exxon Valdez from the normal course to avoid icebergs before he left the bridge.

With an unlicensed and possibly overworked third mate in charge, the 986-foot (300-meter) tanker failed to return to the shipping lanes and ran aground.

Witnesses saw Hazelwood drinking vodka in a local bar before the departure and a blood test showed alcohol several hours after the accident, but a jury found him not guilty on the charge of operating a vessel while under the influence of alcohol.

The toxic crude polluted 1,300 miles (2,000 kilometers) of shoreline and took the lives of an estimated 250,000 seabirds, 2,800 sea otters, 300 harbor seals and as many as 22 killer whales. The cleanup efforts went on for four summers.

"There was a sea change in environmental consciousness," Day said.

"The disaster got people thinking about how we are getting our energy."

New legislation required that all tankers transporting oil through Prince William Sound must have double hulls and be escorted by two tugboats. Contingency planning was ramped up.

But even a quarter century later, remnants of the spill linger on the shores of southern Alaska.

A recent study found hidden pockets of oil on remote rocky beaches.

"We have learned that certain kinds of beaches with boulder are hard to clean up," said lead researcher Gail Irvine from the US Geological Survey, stressing that the mousse-like oil can "persist for decades" once it is in sheltered positions.

- 'Cleanup artist' -

A report by the Exxon Valdez Oil Spill Trustee Council identified in 2010 approximately 50 beach segments with lingering oil, representing a total shoreline length of about 1.5 miles.

"You can dig a hole a foot down and find liquid oil," Jeep Rice, a retired longtime researcher with the National Oceanic and Atmospheric Administration (NOAA), told AFP.

"The oil that's below the surface declines very slowly. It's probably gonna be there for another 50 years."

At least most species have recovered from the environmental disaster.

"Prince William Sound is a functioning ecosystem. The water is clean," Rothchild said.

"Nature is a wonderful thing, nature is its own cleanup artist."