The Transocean's Leaking Oil Is Bad but Not Likely Catastrophic

BP (BP) and the U.S. Coast Guard say about 1,000 barrels of crude oil a day are leaking from the Transocean rig that burned and collapsed in the Gulf of Mexico last week. Coast Guard Rear Admiral Mary Landry, who is overseeing the rescue and cleanup efforts, said at a Saturday press conference. "Absolutely, this is a very serious oil spill." Media reports say the spill covers 400 square miles about 40 miles off the Louisiana shore.

But is it a serious spill? The most well-known oil spill in U.S. history was the wreck of the Exxon Valdez in Prince William Sound in Alaska on March 24, 1989. That incident caused the release of 250,000 barrels of crude. According to a September 1992 report from the NOAA Hazardous Material and Response and Assessment Division, an office within the Commerce Department, several other spills in the last three decades were even larger than the Exxon Valdez. One widely was the March 16,1978, Amoco Cadiz wreck off Brittany France, which spilled at total of 1.6 million barrels, some of which came ashore.

As a map of the areas around Prince William and the Gulf of Alaska in the days after the Exxon Valdez wreck shows, the regional effects of that spill were so great because the ship was close to land, which caused damage to wildlife for hundreds of miles around the wreck.

The Transocean catastrophe isn't likely to threaten the U.S. shoreline with similarly large amount of oil in a small geographic location. And if the well leak can be capped soon, the total spill might be kept under 20,000 barrels. That would be an ecological hazard, but it might not be an awful one.