Dumas Bay seaweed: Stamping out the stink

Dan Smith, Surface Water Quality Program coordinator, and his daughter Melanie, use GPS and a grid to measure the presence of seaweed at select locations at Dumas Bay June 29. Melanie acted as a volunteer. The bright green colored growth is the seaweed. Smith will measure the growth each week throughout the summer.  - Jacinda Howard, The Mirror
Dan Smith, Surface Water Quality Program coordinator, and his daughter Melanie, use GPS and a grid to measure the presence of seaweed at select locations at Dumas Bay June 29. Melanie acted as a volunteer. The bright green colored growth is the seaweed. Smith will measure the growth each week throughout the summer.
— image credit: Jacinda Howard, The Mirror

Federal Way has begun researching and monitoring seaweed blooms that regularly cause a stink at Dumas Bay during the summer months.

In past years, slimy green algae has accumulated heavily on the beach and in the water, causing nearby residents to complain. The sewage-like smell, caused by hydrogen sulfide emitted from the seaweed when it builds up then decays, was especially putrid in 2005 and 2006. The city responded in 2007. The following year, when the growth reached an estimated five to eight tons, the City of Federal Way pursued grants.

Now, city staff is using the money to learn more about the phenomenon. It is tracking the seaweed's accumulation and monitoring the hydrogen sulfide released from the algae. The city is working with the state health department to determine at what point the level of gas emitted poses a danger to the public. The seaweed overgrowth is not limited to Dumas Bay. Seattle's Fauntleroy Cove has battled the same problem for years. But this is one of the first times the problem is being researched by local government.

"We've never done anything this in-depth," said Dan Smith, City of Federal Way Surface Water Quality Program coordinator. "We hope we can derive something meaningful from it."

The work is funded by two grants from the Washington State Department of Ecology. The management grant — $46,620 including matching funds from the city — is going toward community coordination, public education, air monitoring near the beach and planning for emergency seaweed removal.

The research grant — $46,650 with the city's matching funds — is going toward identifying the sources of nitrogen responsible for the seaweed's overgrowth. Seattle Pacific University students are assisting city staff in this area. The grants expire June 30, 2011.

"It's really kind of challenging and a neat project to work on," Smith said. "We're setting the standard."

Growth levels

The seaweed, also known as macroalgae or sea lettuce, is native to Dumas Bay and typically maintains healthy growth levels. In the summer, an abundance of nitrogen in the water pairs with warmer temperatures and fuels the seaweed's growth. The seaweed mats in a continuous blanket across the beach and near the shoreline.

When its layers are broken apart by waves, wildlife or people, they release the hydrogen sulfide responsible for the infamous smell. The gas can adversely affect air quality. At high levels, it can cause health problems to humans and animals. The seaweed has not accumulated so heavily recently as in past years.


Throughout the summer, Smith will venture to the beach to do research. On June 29, he checked air monitors placed at four homes near Dumas Bay. So far, none of the monitors have detected a significant hydrogen sulfide presence.

He also documented the seaweed's growth at six locations across the beach. A GPS is used to ensure the same locations are being assessed each week. A grid, measuring 1 square meter and comprised of 100 small squares, is used in the process. Smith places the grid on the ground and counts the number of squares that are at least half occupied by seaweed. Each square counted represents one percentile. At one location, as of June 29, the seaweed occupied 10 percent of the area. The previous week, it occupied 1 percent, according to Smith's research.

The monitoring process isn't fancy, but Smith hopes it contributes to a greater learning of the causes and solutions to the problem.

"It's not an exact science right now," he said. "There's no book written on what we're doing here."

A resident's reaction

Nearby resident Mike McKasy appreciates the city's efforts. McKasy lives beachside. A person expects a bit of a stench when living by the bay, he said. But the rotten egg smell is not normal.

"It shouldn't smell like sewage," McKasy said. "It shouldn't be a health hazard."

McKasy is proud of the city for taking on a leadership role, he said. At a time when the city, county and state should be concerned about the seaweed, Federal Way has stepped up to address the issue, despite ongoing controversy over which agency is responsible for keeping the seaweed growth in check. The overgrowth affects the quality of air, land and water. It impacts the health of humans and wildlife. It also affects quality of life.

"I think they all should be involved," McKasy said. "Federal Way has stepped up and taken the lead. The county and the state should be stepping up too."

The baseline study that the city is attempting to map is bound to prove useful in coming years, both to Federal Way and other areas taking on seaweed explosions, he said. McKasy is glad to see Federal Way at the forefront.


Beginning in 2007, the city approached several local, regional and statewide agencies about the seaweed. The state's departments of Natural Resources, Fish and Wildlife, Ecology and Health were contacted. Puget Sound Clean Air Agency and Lakehaven Utility District, which operates a nearby treatment plant, were spoken with.

That same year, the Washington State Legislature amended RCW 36.61, authorizing the creation of beach management districts. Funds appropriated by the Legislature were also set aside for the removal of seaweed blooms at selected beaches or near shore areas.

In 2008, Dumas Bay was chosen for a pilot project. Seattle-based Blue Marble Energy used a vacuum-like contraption to suck seaweed from the bay's surface. The seaweed was transported to Seattle, where Blue Marble planned to spend $300 a ton in a process that mimics that of a cow's stomach, turning the seaweed into bio-fuels. Federal Way contributed nearly half of the $40,000 used in the effort.

Several agencies agree seaweed overgrowth poses a threat to the bay and public. None have decided when, how or to what extent to remove the seaweed and who will pay for the endeavor.

Learn more

For more information on the grants, visit the city's website:

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