US oil leak far worse than first thoughtAn oil leak in the Gulf Of Mexico threatening the coast of Louisiana, Texas and the Mississippi estuary is five times worse than previously thought.
The oil is spewing from a rig that exploded and sank last week.
It is now estimated that 5,000 barrels a day are spilling into the ocean rather than the 1,000 the US Coast Guard previously announced.
On Wednesday (local time) clean-up crews conducted a controlled burn of some parts of the slick to stop it reaching environmentally sensitive wetlands.
But authorities have not been able to plug the leak which began when the explosion sank the Deepwater Horizon oil rig leased by BP.
The woman leading the response is Rear Admiral Mary Landry of the US Coast Guard.
"Initially we agreed the estimate was 1,000 barrels per day; working with NOAA (National Oceanic and Atmospheric Administration) daily with overflights, applying disbursements, looking at the trajectories, where the oil going," she said.
"Factoring in the weather, there's a lot of variables in this; this is not an exact science when you estimate the amount of oil.
"However, NOAA is telling me now they prefer we use 5,000 barrels a day as an estimate for what's actually leaked from this well and will continue to leak until BP secures the source."
Complicating matters for BP and the clean-up crews is that previously it was thought there were two leaks - now there are reports of a third.
Authorities are desperate to stop oil polluting the Louisiana coast which is just 37 kilometres away.
Environmental impact
Burning the oil is one way to do it, but that is not enough says Jacqueline Savitz from Oceana, an ocean conservation group.
"This oil spill is a no-win proposition. It's pumping oil into the ocean. We don't know when it will stop," she said.
"The alternatives that have been proposed, such as burning the oil off, may or may not work. They're experimental but they may be the lesser of two evils.
"It will take some of the oil out of the picture, but there'll still be some oil remaining in the ocean and washing up on the beach."
Director of the Oiled Wildlife Care Network in Los Angeles, Michael Ziccardi, says a small group of whales has travelled through the slick, but so far no other animals have been affected.
"If the oil does reach the shore, it's likely animals will be. If it remains offshore, or if the disbursement and the in-situ burning are successful to dissipate the oil, really the highest-risk animals at this point would be the sea turtles because they do feed at the water's surface out there," he said.
Mr Ziccardi says it is vital to keep the oil offshore to stop large-scale environmental damage.
He is going to Louisiana to help plan the emergency response if animals are affected by oil.
"The impact could be extremely large. The marshlands there are very sensitive, very difficult to clean up once it enters that area," he said.
"Certain barrier islands in that area have thousands of breeding pairs of brown pelicans for example, lots of shore birds, lots of other wading birds in the area.
"So, in addition to that you've got impacts on reptiles, amphibians, all the different animals in the ecosystem, so the impact could be very large."
The Gulf of Mexico spill is drawing comparisons to last year's leak from a rig off the coast of Australia that could not be plugged for 10 weeks.
An inquiry has just wrapped up into that incident and the findings are expected to be handed down at the end of the month.
The explosion on the rig in the Gulf of Mexico is the subject of an investigation, but for now that will have to wait.
It is feared changes in the currents and winds could see oil reach land by the weekend.
