Some oil that remains from the Exxon Valdez still as fresh as in '89

Twenty years after the Exxon Valdez oil tanker ran aground, some of the crude buried in intertidal areas remains fresh, fragrant and toxic.

"It has the consistency of crankcase oil — you can smell it, and when we analyze it we find the characteristics of Exxon Valdez oil that was about 2 weeks old," said Jeep Rice, a federal marine scientist who has spent much of the past 20 years studying the aftermath of the largest oil spill in U.S. waters.

Rice and other researchers spent many hours digging more than 9,000 shallow pits on the beaches and in the intertidal areas to survey the lingering oil.

He estimates that the oil is buried beneath some 10 to 15 acres of the sensitive intertidal areas that are rich with clams, mussels and other sea life.

This is less than 1 percent of the total intertidal area of Prince William Sound, but scientists estimate it will take decades, possibly centuries, for this oil to weather and degrade.

— Hal Bernton