Oil Spills in U.S. Coastal Waters: Background, Governance, and Issues for Congress

Publication Date: April 2009

Publisher: Library of Congress. Congressional Research Service


Research Area: Energy; Environment



During the past two decades, while U.S. oil imports and consumption have steadily risen, oil spill incidents and the volume of oil spilled have not followed a similar course. In general, the annual number and volume of oil spills have shown declines -- in some cases, dramatic declines. The 1989 Exxon Valdez spill in Alaskan waters played a large role in stimulating actions that contributed to this trend, particularly the decrease in the annual spill volumes. The Exxon Valdez spill highlighted the need for stronger legislation, inflamed public sentiment, and spurred Congress to enact comprehensive oil spill legislation, resulting in the Oil Pollution Act of 1990 (P.L. 101-380). This law expanded and clarified the authority of the federal government and created new oil spill prevention and preparedness requirements. Moreover, the 1990 legislation strengthened existing liability provisions, providing a greater deterrent against spills. After 1990, spill volume from oil tankers, the vessels that carry and have spilled the most oil, decreased significantly.

Considering that U.S. oil consumption and oil imports have steadily increased, the trend of declining spill incidents and volume in past years is noteworthy. Yet, recent annual data indicate that the overall decline of annual spill events may have stopped. Both consumption and imports are projected to maintain upward movement, and the United States is expected to increase the proportion of its imported oil. More oil-carrying vessels will be entering U.S. waters, and a higher percentage of transported oil will likely travel by vessel. The threat of oil spills may increase if more oil is being transported into and around the nation. This increased threat raises the question of whether U.S. officials have the necessary resources at hand to respond to a major spill. There is some concern that the favorable U.S. spill record has resulted in a loss of experienced personnel, capable of responding quickly and effectively to a major oil spill. Moreover, the level of funding required to respond to such a spill, particularly its aftermath, may be currently inadequate, according to U.S. Coast Guard reports.

No oil spill is entirely benign. Even a relatively minor spill, depending on the timing and location, can cause significant harm to individual organisms and entire populations. Marine mammals and bottom-dwelling species are especially vulnerable to a nearby spill. However, the effects of oil spills can vary greatly. Oil spills can cause impacts over a range of time scales, from only a few days to several years, or even decades in some cases.

This report reviews the history of oil spills, presents relevant data, and identifies the legal authorities governing oil spill prevention, response, and cleanup.