Stories about Getting to Clean Water: Understanding and Controlling Sea Lettuce in Dumas Bay

By Diane Dent, Water Quality Stories Lead, Water Quality Program

Map of Dumas Bay, King County, Washington.

Dumas Bay, near Federal Way in King County, is part of Puget Sound. Three streams drain into the urban 40-acre bay, which is part of the Puyallup-White watershed.

The problem

Residents living along Dumas Bay began to notice excessive amounts of macro algae, better known as sea lettuce, and a very strong odor in the air. Ecology performed inspections and soon determined they were being caused by the sea lettuce.

In 2007, Federal Way began consulting with Ecology about the problem, as well as working with the Departments of Fish and Wildlife, Natural Resources, and Health; Lake Haven Utility District, the Puget Sound Clean Air Agency, and local residents.

Federal Way's Surface Water Management (SWM) Division goals for this project included:

• Gaining an understanding of the causes of excess sea lettuce growth and its associated odor problem.

• Helping watershed residents understand the problem and what, if anything, they could do to alleviate it.

• Assessing the health risk posed by hydrogen sulfide (H2S) gases from the decomposing seaweed.

To find out the results of  Federal Way's project, read this full story online.

Story written by Tricia Shoblom, Ecology Northwest Regional Office

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Water quality success stories provide a wealth of information associated with novel project designs, funding ideas, and useful resource suggestions. Some are clear successes; others supply valuable lessons to help us grow in our understanding of water quality protection and restoration. Stories illustrate successes gained from cooperation among Washington’s citizens and organizations.

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