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 than 13 percent
worldwide.