What happened on 24 March 1989

The Oil Spill
 Shortly after midnight on 24 March 1999, the T/V Exxon Valdez ran aground on Bligh Reef in Prince William sound, Alaska, spilling almost eleven million gallons (about 18 000 000 litres) of North Slope Crude oil. It was the largest tanker spill in United States history. That spring the oil moved along the coastline of Alaska, contaminating portions of the shoreline of Prince William Sound, the Kenai Peninsula, lower Cook Inlet, the Kodiak Archipelago, and the Alaska Peninsula. Oiled areas included a National Forest, four National Wildlife Refuges, three National Parks, five State Parks, four State Critical Habitat Areas, and a State Game Sanctuary. Oil eventually reached shorelines nearly 600 miles (960 km) southwest from Bligh Reef where the spill occurred.

During 1989, efforts focused on containing and cleaning up the spill, and rescuing oiled wildlife. Skimmers worked to remove oil from the water. Booms were positioned to keep oil from reaching salmon hatcheries in Prince William Sound and Kodiak. A fleet of private fishing vessels known as the Mosquito Fleet played an important role in protecting these hatcheries, assisting the skimmers, and capturing oiled wildlife and transporting them to rehabilitation centres. Exxon began to clean up the beaches under the direction of the US Coast Guard with advice from federal and state agencies and local communities. Several thousand workers cleaned shorelines, using techniques ranging from cleaning rocks by hand to high-pressure hot-water washing. Fertilisers were applied to some oiled shorelines to increase the activity of oil-metabolising microbes, an activity known as `bioremediation'.

The 1989 shoreline assessment, completed after the summer cleanup ended, showed that a large amount of oil remained on the shorelines. In the spring of 1900, the shoreline was again surveyed in a joint effort by Exxon and federal and state governments. The survey showed that much work remained to be done. The principal clean-up method used in 1990 was to manually remove the remaining oil, but bioremediation and relocation of oiled beach material to the active surf zone were also used in some areas.

Shoreline surveys and limited clean-up work occurred in 1991, 1992, 1993 and 1994. In 1992, crews from Exxon and the state and federal governments visited 81 sites in Prince William Sound and the Kenai Peninsula. They reported that an estimated seven miles (approx. 11 km) of the 21.4 miles (approx. 32 km) of shoreline surveyed still showed some surface oiling. This number does not include oiling that may have remained on shorelines set aside for monitoring natural recovery. The surveys also indicated that subsurface oil remained at many sites that were heavily oiled in 1989. No sites were surveyed on Kodiak Island or the Alaska Peninsula in 1992. Earlier surveys suggested that most of the light oil (scattered tar balls and mousse) which remained on Kodiak Island and the Alaska Peninsula would degrade by 1992. While there may be a few exceptions, the surveys determined that the cost and potential environmental impact of further clean-up was greater than the problems caused by leaving the oil in place. The 1992 clean-up and the 1993 shoreline assessment were concentrated in those areas where oil remained to a greater degree - Prince William Sound and the Kenai Peninsula.

In 1994, restoration workers performed manual treatment to accelerate degradation of surface oil on approximately a dozen important subsistence and recreational beaches in western Prince William Sound. They also performed manual treatment to accelerate degradation of subsurface oil beneath approximately a dozen oiled mussel beds in protected areas of Prince William Sound.

Natural Resource Damage Assessment
During the first summer after the spill, one state and three federal government agencies directed the Natural resource Damage Assessment field studies to determine the nature and extent of the injuries as needed for litigation purposes. The federal agencies were the US Department of the Interior, the US Department of Agriculture and the National Oceanic and Atmospheric Administration. The state agency was the Alaska Department of Fish and Game. Expert peer reviewers provided independent scientific review of ongoing and planned studies and assisted with the synthesis of results. Most damage assessment field studies were completed during 1991.