Meanwhile, Coast Guard chief warrant officer Adam Wine told Bellona Web that tar balls believed to be from the Gulf of Mexico oil spill are washing up on Alabama’s Dauphin Island. Similar Coast Guard reports have emerged that dead sea life has been washing up on the beaches of Ship Island, one Mississippi’s barrier islands.

Oil sheen has been predicted by the National Oceanographic and Atmospheric Administration (NOAA) to start washing ashore in Gulf communities by the weekend. Coast Guard helicopters monitoring the oil’s progess were heard to be getting closer and closer to shore on Saturday afternoon.

The Coast Guard and the Minerals Management Service are holding public hearings on the investigation into what caused the Deepwater Horizon rig explosion 50 miles off the Louisiana coast. The agencies said today that the hearings will be held on Tuesday and Wednesday in New Orleans. The joint investigation will be co-chaired and staffed by members of both agencies.

As for BP’s faltering efforts with its containment dome, BP Chief Operating Officer Doug Suttles told reporters that hydrates – crystals that look like slush – had formed at the top of the dome, clogging the opening that is supposed to funnel oil up to a waiting ship.

The four-story, 98-ton metal structure was moved aside and is resting nearby on the seafloor, 5,000 feet(1,500 metres) beneath the surface, while engineers attempt to figure out a solution.

Suttles expects it will take several days to try to remedy the problem.  Over the past day officials have been careful not to raise expectations about this containment strategy, which has never before been attempted at such ocean depths.

Officials were at pains Saturday to emphasise they have not yet given up hope of capping the leaks which are hemorrhaging an estimated some210,000 barrels a day.

“I wouldn’t say it’s failed yet,” said BP’s Suttles, whose company is responsible for the cleanup.

“What we attempted to do last night didn’t work because these hydrates plugged up the top of the dome.”

Clearing out the slushy crystals is easy –  the metal chamber just has to be raised to warmer levels, Suttles told reporters. Keeping the crystals out so that a pipe can be lowered into the dome to suck the oil to a waiting barge is another matter.

Engineers are looking at ways to heat the frigid water in the dome, among other options.

BP has already begun drilling relief wells to stem the flow, but it will take about three months for them to be operational.

It is also considering other temporary measures like trying to plug the leaks by injecting ground-up material in a “junk shot,” but Sutters said BP cannot proceed until it is sure that it “won’t make the situation worse.”

An estimated 3.5 million gallons of oil has formed a slick about the size of Puerto Rico which threatens the fragile coastal wetlands of Louisiana and the beaches of Mississippi, Alabama and Florida.

Favorable winds have kept the bulk of the oil from reaching shore since the BP-leased Deepwater Horizon sank some 50 miles (80 km) southeast of Venice, Louisiana on April 22, two days after an explosion that killed 11 workers

But with a thin sheen of oil now lapping Louisiana’s coastal islands, local leaders begged for more boom to protect vulnerable coastal wetlands and wildlife preserves, as well as multi billion-dollar fishing and tourism industries.