Lessons for Deepwater Horizon that come directly out of the history books

There are many parallels between the Deepwater and Ixtoc 1 oil spills, but the environmental damage

could be much worse

Juliette Jowit, The Guardian

It was a Saturday in June when workers on a drilling platform in the Gulf of Mexico hit a soft patch 3,600m below the sea floor. Worried that the softer mud would stop circulating to keep pressure even, workers immediately tried to remedy the problem. But it was not enough: the following day drilling equipment ignited leaking oil and gas and caused a massive explosion and the burning platform collapsed into the ocean.

The Ixtoc 1 disaster in 1979 became what is still the world's second worst-ever oil spill. The worst was off the coast of Kuwait during the Gulf War in 1991.

Ixtoc 1 owners, Petroleos Mexicanos (Pemex), the Mexican state oil company, could not cap the well for 10 long months, by which time an estimated 90m gallons of oil had escaped. Much of it evaporated, was dispersed by chemicals or burned off in the fire, but the remainder drifted in a greasy slick up to 60-70 miles long on to the US coastline, damaging wildlife, fishing and tourism. A report for the US government later concluded that the lost oil, equipment and clean up cost Pemex $498m - more than US$1bn in today's money - and there were claims for damages of more than $400m, making it "probably the most expensive oil spill in history".

BP will be hoping that the Deepwater Horizon disaster does not, as environmentalists are warning, turn into "Ixtoc 2". The parallels between the two accidents are in many ways striking: both drilling rigs were in the same region; both have been blamed on failed safety valves which should have prevented early problems escalating; both appear to be hard to cap off and stop; and both leaks caused huge quantities of oil to be driven by prevailing winds and tides towards the US.

Despite a big operation to use skimmers and booms to protect the coast, Ixtoc 1 damaged 162 miles of Texas beaches. Birds were badly affected with 1,421 oiled royal terns, blue-faced boobies, sanderlings, willets, plovers, herons, noddy terns, and snowy egrets rescued, while thousands more were driven away from their feeding and breeding grounds, many of them not returning for years afterwards. The impact on smaller species was - as so often - impossible to calculate.

The damage caused by the Deepwater spill could be worse, Athan Manuel, director of lands protection for the Sierra Club environmental group in the US, told the Guardian. Although the industry has three decades more experience, the Deepwater well head was in much deeper water, said Manuel. But the biggest difference is the part of the US the oil is heading for, he said: "The spill now is threatening to hit wetlands, marshes and estuaries where it's virtually impossible to get oil out without damaging the ecological system. If this oil washes ashore [on the sandy beaches of] Florida it could be similar to Ixtoc 1. If it comes ashore in Louisiana it could be a lot worse."

The best hope for BP and the equipment owners Transocean, who are both expecting major law suits over the incident, is that official reports into some oil spills have found initial fears of the damage were much worse than the resulting problems. Notably several studies of the south west coast of Wales after a major spill from the oil tanker Sea Empress in 1996 found that bird populations had recovered and beaches became clean more quickly than at first believed.

However, such results depended on many natural factors such as the spill occurring out of important breeding or feeding seasons, and heavy weather to break up the oil, said Nigel Clark, head of projects for the British Trust for Ornithology, who has worked on several oil accidents. In the Gulf of Mexico the time of year is certainly not a good one, with huge migrations of species like semipalmated sandpipers and western sandpipers from South America through the US on their way north to the Arctic. Sea birds in particular are at risk because the oil makes the sea look calmer and so they are more likely to land on it to rest, said Clark.

"These birds are very often under pressure from a large number of other things, therefore it's one more pressure on them that means they are in real danger," he added.