Elliott Bay Sheen Incident
(Information on this site is considered to be accurate at the time of posting, but is subject to change as new information becomes available.)

Final Update and Summary 10:00 a.m. 05/01

On March 17, 2006, Ecology and the U.S. Coast Guard responded to an oil spill that occurred on Elliott Bay in Seattle.  The spill soon spread in ribbons between West Waterway off Harbor Island and three miles north to an area off Elliott Bay Marina.  State and federal agencies responded by helicopter, boat, and inspections on shore to determine:

• Size, location, and content of the oil spill

• Whether a spill was still in progress that should be stopped or contained

• Environmental effects

• The source of the spill

State and local responders worked diligently to find the source of the March 17 spill.  However, the exact source remains unknown.  Ecology determined the spill likely involved no more than 50 gallons of lubricating oil.  Even in small amounts, lubricating oil can spread quickly in water and over surprisingly large areas. 

The March 17 oil slick was too thin to clean up.  Thin slicks typically are just molecules thick and no known equipment or methods can remove it from the environment.  A combination of rain, wind, and afternoon sun eventually dispersed nearly all the spill the same day.  Even when a spill cannot be recovered and disperses, the oil adds toxic pollutants to an already threatened Puget Sound.  While no oiled birds or wildlife were reported on March 17, all petroleum products are toxic, and no spill of any size is acceptable. 

 Two possible sources attracted media and public attention on day of the spill:

• A cargo ship anchored off Smith Cove, which was surrounded by part of the sheen.

• A storm drain on Harbor Island that had sheen at its outfall to the West Waterway.

Ecology inspectors boarded the ship and took oil samples, but oils aboard the vessel later proved to not match the oil in the bay.

There had been small sheens at the outfalls of two Seattle Public Utilities (SPU) storm drains – at S.W. Lander St. and S.W. Florida St. – that serve portions of Harbor Island and empty into the West Waterway on nine occasions since 2001, when the lines were completed.   SPU, Ecology, the U.S. Environmental Protection Agency (EPA) and the Coast Guard established a joint working group in January 2006 to determine the source of these sheens.  Harbor Island is an EPA Superfund site.

On March 17, the crew of a Coast Guard patrol boat noticed sheen at the Lander St. outfall and collected a sample.  Ecology’s Manchester Environmental Laboratory later determined that this sample matched samples collected March 17 by an Ecology boat crew from the sheen in the middle of the bay.

 SPU conducted video tests of both lines the week after the spill, but found no breaks or damage.   Also, Ecology collected samples of lightly oiled water from inland catch basins.  The lab identified the traces of oil in the samples as lubricating oil, but the samples were too small to determine whether they were identical to the earlier samples from the West Waterway and Elliott Bay.

Because of Harbor Island’s flat terrain and low elevation, tidal water enters the storm drains from the outfalls during high tides and reaches deeply inside.  Oily water could have flowed into the line from the waterway.  

Ecology and the other members of the Harbor Island storm drains working group continue their investigations.

In 2004 alone, Ecology responded to 460 similar unsolved small-volume oil sheens on waters in Washington involving fuels or lubricants.  The department promotes good care of motor vessels (please see a news release from earlier this week at http://www.ecy.wa.gov/news/2006news/2006-070.html).