The Exxon Valdez oil spill occurred in Prince William Sound, Alaska, on March 24, 1989, when Exxon Valdez, an oil tankerbound for Long Beach, California struck Prince William Sound's Bligh Reef and spilled 260,000 to 750,000 barrels (41,000 to 119,000 m3) of crude oil. It is considered to be one of the most devastating human-caused environmental disasters. The Valdez spill was the largest ever in U.S. waters until the 2010 Deepwater Horizonoil spill, in terms of volume released. However, Prince William Sound's remote location, accessible only by helicopter, plane, and boat, made government and industry response efforts difficult and severely taxed existing plans for response. The region is a habitat for salmon, sea otters, seals and seabirds. The oil, originally extracted at the Prudhoe Bay oil field, eventually covered 1,300 miles (2,100 km) of coastline, and 11,000 square miles (28,000 km2) of ocean.Then Exxon CEO, Lawrence G. Rawl, shaped the company's response.
According to official reports, the ship was carrying approximately 55 million US gallons (210,000 m3) of oil, of which about 11 to 32 million US gallons (42,000 to 120,000 m3) were spilled into the Prince William Sound. A figure of 11 million US gallons (42,000 m3) was a commonly accepted estimate of the spill's volume and has been used by the State of Alaska's Exxon Valdez Oil Spill Trustee Council, the National Oceanic and Atmospheric Administration and environmental groups such as Greenpeace and the Sierra Club.Some groups, such as Defenders of Wildlife, dispute the official estimates, maintaining that the volume of the spill, which was calculated by subtracting the volume of material removed from the vessel's tanks after the spill from the volume of the original cargo, has been underreported.Alternative calculations, based on the assumption that the official reports underestimated how much seawater had been forced into the damaged tanks, placed the total at 25 to 32 million US gallons (95,000 to 120,000 m3).
During the first few days of the spill, heavy sheens of oil covered large areas of the surface of Prince William Sound.