An omni-boom blasts oil-coated rocks in an attempt to clean gross oil contamination from a beach on LaTouche Island. NOAA biologists have concluded that such techniques may do more harm than good. (Photo credit: Exxon Valdez Oil Spill Trustee Council)   A NOAA biologist examines freshly excavated live adult clams from heavily oiled beach sediments on Block Island, Prince William Sound, Alaska. Juvenile clams generally do not survive as well as adults on oiled beaches. (Photo credit: OR&R, NOAA)

The scientists who monitored the oiled parts of Prince William Sound wanted to study the shoreline’s ecological recovery after an environmental disaster like the Exxon Valdez spill, and then use those lessons to better respond to future oil spills. Right now, their task is still incomplete. However, some of their findings have changed the way they think about cleaning up oil spills. Following are some examples of what they have learned:

More limited and measured use of aggressive cleanup methods, such as hot-water washing, would help to minimize the severe effects scientists have observed in plant and animal communities.

Using water to flush an oil-contaminated beach may also wash away fine-grained sediments, such as sand and nutrients, which small organisms need to successfully colonize. Sometimes, it takes years for the fine sediment to return.

Adult animals such as clams may survive in oil-contaminated beaches, but juveniles don’t do as well.

Oil that penetrates deeply into beaches can remain relatively fresh for years and can later come back to the surface and affect nearby animals.

After the Exxon Valdez spill, beaches were reworked by heavy machinery to move heavily oiled upper intertidal sediments into the middle intertidal zone, where they could be washed by the surf and where the oil could be collected in booms. After such large-scale excavations, it can take many years for the beach sediments to recover.

Rocky rubble shores should be of high priority for protection and cleanup because oil tends to penetrate deep and weather very slowly in these habitats, prolonging the harmful effects of the oil when it leaches out.

A brown sediment plume and sheens of refloated oil drift away from this oiled beach as it is cleaned by a team applying high-pressure, hot-water washing. Refloating of oil and the release of sediments are often unavoidable consequences of shoreline cleanup that can cause additional environmental harm. (Photo credit: OR&R, NOAA)