Historically, oil and gas exploration, petroleum production, and transportation-related spills have been significant sources of oil in the oceans. The second-largest marine spill in the world was a 1979 “blowout” of a Mexican exploratory oil well that released about 140 million gallons of crude oil into the open sea in the southern Gulf of Mexico. During the past decade, however, improved production technology and safety training of personnel have dramatically reduced both blowouts and daily operational spills. Today, accidental spills from platforms represent about 1 percent of petroleum discharged in North American waters and about 3 percent worldwide.Although the amount of oil transported over the sea continues
to rise, transportation-related spills are down. The U.S. Oil Pollution Act of 1990, enacted in response
to the Exxon Valdez disaster,required older vessels to be phased out. Most tankers now
have double-hulls or segregated tank arrangements that dramatically reduce spillage.Transportation spills now account for less than four percent of the total petroleum released in North American waters and less than13percent