Mike Angaiak crouches on his knees on the rocky beach at Snug Harbor, scraping the bottom of a sandy pit with a trowel.
Finding nothing, he refills the pit with gray sand and rocks and moves on to a spot about six feet away. Angaiak tosses aside rocks and boulders and starts to dig another hole. But this time, the sand beneath the rocks is deep brown and oily.
"Ugh," he says as he lifts an oiled rock from the freshly dug hole and sniffs it. "You can smell it."
Angaiak, from the Prince William Sound village of Chenega Bay, is a member of a crew of eight working on this stretch of shoreline at Snug Harbor. Workers are spending the summer searching for the crude that remains from the Exxon Valdez spill more than a dozen years ago.
"There's no rocket science to finding it," said Jeff Short, a research chemist with the National Marine Fisheries Service, the agency that began conducting the shoreline survey in May.
Snug Harbor is 55 miles southwest of Bligh Reef, where the tanker Exxon Valdez ran aground March 24, 1989, gushing 11 million gallons of thick black crude oil into the waters of Prince William Sound. Once pristine beaches were blanketed with oil and thousands of birds and marine mammals perished.
The accident still stands today as the nation's worst oil spill.
Efforts to clean up the spill ended in 1993. The tides and storms washed away much of the oil and the sound has largely recovered. But persistent pockets of pollution remain.
"It's been a big surprise," Short said. "Most people, including us, would have thought it would be gone by now."
A 1994 study by the National Marine Fisheries Service estimated that based on the behavior of oil, about 70% of it evaporated into the air or biodegraded in the ocean or on shore, and 14% was recovered through cleanup efforts.
About 1.4 million gallons, or 13%, were estimated to remain in the mud, sand and sediments in the Gulf of Alaska and Prince William Sound. About 217,000 gallons, or 2%, were thought to remain on beaches.
Even today, workers are finding oil about 10% of the time on beaches that had been heavily oiled, Short said.
Pit after pit they dig, an expected 7,000 by the end of summer. And whenever they find oil, they map the size and location of the oil patch.
The amount of oil will be estimated by sampling. From that information, Short will do a statistical analysis to produce an estimate of oil remaining in Prince William Sound, without having to examine all of the beaches. He expects his study to be completed in about a year.
No effort is being made to clean up the oil found this summer. There is simply no feasible way to remove what remains trapped beneath the surface along thousands of acres of shoreline.
"We've found that the available technologies--steam and detergents--can be as injurious to the environment as the oil," said Phillip Mundy, science coordinator for the Exxon Valdez Oil Spill Trustee Council.
The council directs the spending of the $900-million settlement Exxon paid to the state and federal governments and it is funding the $572,000 beach survey. It also set up a trust fund to pay for scientific monitoring of the sound in perpetuity.
The effort to quantify how much oil remains is intended to answer lingering questions about the effects of hydrocarbons on fish and wildlife. There is evidence that potentially lethal doses of oil occasionally leach into Prince William Sound stream beds where salmon spawn, and some birds and marine mammals continue to show evidence of ongoing exposure to oil, Short said.
Tom Cirigliano, a spokesman for Exxon Mobil Corp., would not comment on the study, but said the company worked on cleaning up the oil until state and federal officials called a halt.
"There were certain areas of Prince William Sound that the state and the federal governments determined that no further cleaning should take place because the cleaning would cause more harm to the environment," he said. "Of course there are places in Prince William Sound where, if you look hard enough, you can find Valdez oil."
As water laps the shore of Snug Harbor, it is hard to imagine this quiet beach was once the scene of an environmental disaster.
But the workers moving across the beach with shovels and picks find spots where oil has soaked into the sand. Their work is backbreaking, time-consuming and tedious, and the crew puts in long days, the hours dictated by the tides.
"Some beaches are easier than others," said Mandy Lindeberg, the field chief supervising the project for the National Marine Fisheries Service.
Just a few days earlier and about 18 miles north of here, a crew scrambled over wet, mossy boulders in the shadow of a dense spruce forest at Northwest Bay on Eleanor Island. The beach looks idyllic, but tiny, black globules of oil can be found under rocks and floating in the tidal pools.
"It's really the topography that dictates how long the oil is going to stay," Lindeberg said.