What have been the largest oil spills in U.S. history? Coastal Pollution Tutorial

A man on a boat with a camera filming oil in the water with ships and an oil rig in the background. — *Responders survey oil in the water during the Deepwater Horizon oil spill in 2010. This oil well blowout was the largest oil spill in U.S. waters (Credit: NOAA).*

The first large oil spill that inspired significant environmental awareness in the U.S. occurred in 1969. An oil production platform experienced a blowout off the coast of Santa Barbara, California. Oil and gas leaked from multiple points over the course of 10 days, making it difficult to assess just how much oil was released. NOAA estimated that between 1.4 and 4.2 million gallons of oil were released into the ocean.

The size and scope of this environmental disaster led to several historic moments for conservation. Important environmental events soon after the Santa Barbara oil spill included:

1970: The National Environmental Policy Act, which established policy and goals for the protection, maintenance, and enhancement of the environment
1970: The first Earth Day celebration
1970: The creation of the U.S. Environmental Protection Agency
1972: The Clean Water Act, which set water quality standards and regulated pollution in U.S. waters
1972: The Marine Mammal Protection Act
1972: The Marine Protection, Research and Sanctuaries Act
1973: The Endangered Species Act

On March 24, 1989, the tanker Exxon Valdez grounded on Bligh Reef in Alaska's Prince William Sound, rupturing its hull and spilling nearly 11 million gallons of Prudhoe Bay crude oil into the waters (Credit: NOAA).

Another history-making oil spill in the U.S. was the Exxon Valdez tanker spill. On March 24, 1989, the fully-loaded tanker ran aground on the Bligh Reef in Alaska. Nearly 11 million gallons of oil spilled into the sensitive habitats of Prince William Sound. At the time, it was the largest single oil spill and one of the worst environmental disasters in American history.

This event motivated lawmakers to protect the environment from the threat of future oil spills. They signed the Oil Pollution Act in August of 1990. This law strengthened the federal government’s ability to prevent and respond to catastrophic oil spills. It also made sure that those responsible for the spill had to restore the environment and compensate the public for its lost uses (like beach and recreational fishery closures), from the time of the spill until the natural resources fully recovered.

On April 20, 2010, an explosion on the Deepwater Horizon oil well drilling platform killed 11 workers, and started the largest marine oil spill in U.S. history, releasing millions of gallons of oil into the Gulf of Mexico (Credit: NOAA). — The Deepwater Horizon oil spill impacted the entire Gulf of Mexico, from deep-sea communities to more than 1,300 miles of shoreline (Credit: NOAA). Learn more about what happened during the Deepwater Horizon oil spill.

The largest marine oil spill in U.S. history was the Deepwater Horizon oil spill. On April 20, 2010, an explosion on the oil drilling rig Deepwater Horizon in the Gulf of Mexico tragically killed 11 workers. Two days later, the rig sank to the seafloor. Oil began to spew from the underwater well, and continued for nearly three months. Throughout the crisis, 134 million gallons of oil—enough to fill more than 200 Olympic-sized swimming pools—spilled into the Gulf of Mexico before the well was finally capped successfully on July 15, 2010.