Oil spills

Keep exploring 

Find even more resources on oil spills in our searchable resource database.

Oil is an ancient fossil fuel that we use to heat our homes, generate electricity, and power large sectors of our economy. But when oil accidentally spills into the ocean, it can cause big problems. Oil spills can harm sea creatures, ruin a day at the beach, and make seafood unsafe to eat. It takes sound science to clean up the oil, measure the impacts of pollution, and help the ocean recover.

A sea turtle covered in oil.

Juvenile Kemp's ridley sea turtle oiled in the Deepwater Horizon spill in 2010. (Image credit: Blair Witherington/Florida Fish and Wildlife Conservation Commission)

What is oil?

Crude oil, the liquid remains of ancient plants and animals, is a fossil fuel that is used to make a wide range of fuels and products. Oil is found below ground or below the ocean floor in reservoirs, where oil droplets reside in “pores” or holes in the rock. After drilling down and pumping out the crude oil, oil companies transport it by pipes, ships, trucks, or trains to processing plants called refineries. There it is refined so it can be made into different petroleum products, including gasoline and other fuels as well as products like asphalt, plastics, soaps, and paints.

How do oil spills happen?

Oil spills are more common than you might think, and they happen in many different ways. Thousands of oil spills occur in U.S. waters each year. Most of these spills are small, for example when oil spills while refueling a ship. But these spills can still cause damage, especially if they happen in sensitive environments, like beaches, mangroves, and wetlands.

Large oil spills are major, dangerous disasters. These tend to happen when pipelines break, big oil tanker ships sink, or drilling operations go wrong. Consequences to ecosystems and economies can be felt for decades following a large oil spill.

Where do oil spills happen?

Oil spills can happen anywhere oil is drilled, transported, or used. When oil spills happen in the ocean, in the Great Lakes, on the shore, or in rivers that flow into these coastal waters, NOAA experts may get involved. The Office of Response and Restoration’s mission is to develop scientific solutions to keep the coasts clean from threats of oil, chemicals, and marine debris.

A map showing the Largest Oil Spills Affecting U.S. Waters from 1969 - 2024. 49 oil spills are shown, affecting coastal waters in Alaska, down the West Coast, off Hawaii, the Gulf of Mexico and Caribbean, the East Coast, and the Great Lakes. More information can be found at https://response.restoration.noaa.gov/oil-and-chemical-spills/oil-spills/largest-oil-spills-affecting-us-waters-1969.html.
 Largest oil spills affecting U.S. waters since 1969-2017. (NOAA/Office of Response and Restoration)


How do oil spills harm or kill ocean life? 

Where the oil is spilled, what kinds of plants, animals, and habitats are found there, and the amount and type of oil, among other things, can influence how much harm an oil spill causes. Generally, oil spills harm ocean life in two ways:

Fouling or oiling: Fouling or oiling occurs when oil physically harms a plant or animal. Oil can coat a bird’s wings and leave it unable to fly or strip away the insulating properties of a sea otter’s fur, putting it at risk of hypothermia. The degree of oiling often impacts the animal’s chances of survival.

Oil toxicity: Oil consists of many different toxic compounds. These toxic compounds can cause severe health problems like heart damage, stunted growth, immune system effects, and even death. Our understanding of oil toxicity has expanded by studying the effects of the 2010 Deepwater Horizon oil spill.

Wildlife recovery, cleaning, and rehabilitation is often an important part of oil spill response. However wildlife is difficult to find and catch, oil spills can happen over wide areas, and some animals (like whales) are too big to recover. Unfortunately, it’s unrealistic to rescue all wildlife impacted during oil spills.

Who cleans up an oil spill — and how?

The U.S Coast Guard is primarily responsible for cleaning up oil spills, while NOAA experts provide scientific support to make smart decisions that protect people and the environment. There are different equipment and tactics that trained experts can use to contain or remove oil from the environment when a spill occurs. Booms are floating physical barriers to oil, which help keep it contained and away from sensitive areas, like beaches, mangroves, and wetlands. Skimmers are used off of boats and can “skim” oil from the sea surface. In situ burning, or setting fire to an oil slick, can burn the oil away at sea, and chemical dispersants can break up oil slicks from the surface.

However, cleanup activities can never remove 100% of the oil spilled, and scientists have to be careful that their actions don’t cause additional harm. After the Exxon Valdez oil spill in 1989, scientists learned that high-pressure, hot-water hoses used to clean up beaches caused more damage than the oil alone. Sensitive habitats need extra consideration during oil spill cleanup.

Who pays for oil spill cleanup and restoration? 

The Oil Pollution Act of 1990 established (among other things) that those responsible for oil spills can be held responsible to pay for cleanup and restoration. This process of assessing the impacts of a spill and reaching a settlement to fund restoration projects is called Natural Resource Damage Assessment (NRDA). Federal, state, and tribal agencies work together with the party responsible for the oil spill throughout NRDA and select restoration projects with help from the public.

Working with partners from state, tribal, and federal agencies and industry, NOAA helps to recover funds from the parties responsible for the oil spill, usually through legal settlements. Over the last 30 years, NOAA has helped recover over $9 billion from those responsible for the oil spill to restore the ocean and Great Lakes.

How does NOAA help after an oil spill?

When a person gets sick, a doctor evaluates their symptoms, diagnoses a problem, and then prescribes a treatment to help them get better. That’s also what NOAA experts do after an oil spill: they evaluate what happened, assess the impacts, and then design restoration projects to help the ocean recover. Restoration isn’t the same as cleanup. It requires projects like building marshland or protecting bird nesting habitat to actively bolster the environment.

Restoration projects are important because they speed up the amount of time it takes for different species and habitats to recover. In addition to restoring habitats, the group responsible for the spill may also be held accountable for restoring access to natural spaces by constructing parks, boat ramps, and fishing piers.

What are the largest marine oil spills in American history?

There are three oil spills that stand out in American history, each of which was the largest oil spill into American waterways at the time. In 1969, a blowout on an offshore platform off the coast of Santa Barbara, California, spilled over four million gallons of oil. In 1989, the Exxon Valdez oil tanker ran aground in the Prince William Sound in Alaska, spilling over 11 million gallons of oil.

The largest marine oil spill in all of U.S. history was the Deepwater Horizon spill. On April 20, 2010, an explosion occurred on the Deepwater Horizon drilling platform in the Gulf of Mexico, killing 11 people. Before it was capped three months later, approximately 134 million gallons of oil had spilled into the ocean. That is equivalent to the volume of over 200 Olympic-sized swimming pools. An $8.8 billion settlement for restoration was reached in 2016, and restoration is still continuing today.


Though we tend to be the most familiar with the massive incidents like Deepwater Horizon, did you know that thousands of smaller oil spills occur each year, some spilling less than a barrel of oil? Oil spills, in addition to nonpoint source pollution, threaten our ocean ecosystem. Learning about pollution, as well as our role in our ecosystem, can help protect ocean habitats by improving stewardship behaviors.

Keep exploring 

Find even more resources on oil spills in our searchable resource database.