Oysters growing on a half shell will mature and be used to filter contaminants in the pilot project.
Oysters growing on a half shell will mature and be used to filter contaminants in the pilot project.

Washington Public Lands Commissioner Hilary Franz came out to Elliott Bay on Monday to talk up the oysters growing in the shallows that are expected to provide natural filtration of pollutants in the Puget Sound.

The Port of Seattle teamed up with the Puget Sound Restoration Fund and Washington Department of Resources to seed the bay with native Olympia oysters back in October as part of its Blue Carbon Pilot Project.

Franz is charged with overseeing the management of 2.6 million acres of aquatic lands. The oyster bed will eventually cover just 25 acres, but the mollusks are expected to filter nearly 50 million gallons of water per day, trapping environmentally harmful pollutants inside them.

“Oysters are one of the cleanest ways that we can clean out our waterways,” Franz said.

There are a number of oyster aquaculture projects in rural parts of the state, Franz said, but the Blue Carbon Pilot Project is unique due to its urban environment. The oysters in Elliott Bay will be catching contaminants from stormwater runoff, metals from the bottom of boats in Elliott Bay and drainage coming down from Magnolia.

“You should not eat these oysters,” Franz said.

But the oysters that are fit for consumption in Washington make up a $20 million a year industry, and ocean acidification is having an impact, Franz said.

Port of Seattle Commissioner Fred Felleman said the goal with the project is to remove 1,000 gallons of combusted gasoline per year from the water.

The Puget Sound Restoration Fund has spent a decade working on restoring the Olympia oyster population, said PSRF deputy director Jodie Toft. They were heavily harvested starting in 1850, she said, and the impacts were noticeable by the early 1900s. That’s when the non-native Pacific oyster was introduced to the Puget Sound.

Olympia oysters reproduce naturally, and have other advantages to an inorganic, mechanical filtration system.

“The oysters work cheap,” said Jon Sloan, senior environmental program manager for the Port of Seattle. “They work 24/7, and they don’t require a paycheck once they’re installed.”

Oysters won’t be doing all the work on their own. They will be supported by bull kelp and eelgrass.

Divers planted Bull kelp in Elliott Bay in February. Five pyramid-shaped anchors were set up in a grid, with kelp growing on nylon twine. The baby kelp was grown at the Manchester Research Station in Port Orchard, Toft said. The hope is to see it just below the water’s surface in Elliott Bay by early May.

“It grows super fast and super big,” she said. “Kelp are kind of fast and furious.”

But keeping the kelp reproducing year after year is tough, Toft said, and the bull kelp planted in February will likely start dying off in late summer.

Sloan said plans are to use the dead kelp that washes ashore for composting, along with shellfish biomass. The port plans to test the compost in Centennial Park.

Eelgrass is perennial, hardy and healthy here in the Puget Sound, said Micah Horwith, a coastal scientist leading DNR’s Climate Change and Ocean Acidification program.

“Around the world it’s in dramatic decline,” he said.

The eelgrass planted in Elliott Bay is being monitored, as are nine other eelgrass sites, to help understand its carbon sequestration power. Each site has two devices for testing water quality — one inside the eelgrass and one outside — that check the pH level of the water, chlorophyll and temperature every 10 minutes, Horwith said.

The data collected could make a case for stronger eelgrass protections or increased restoration based on its recognized value.

The Port of Seattle has its submersible robot Ringo that can collect sediment samples and test water quality.

Felleman highlighted the food chain at stake without green initiatives to combat climate change and ocean acidification. Herring feed on eelgrass, he said, and later become food for the salmon that feed the orcas.

“We know the killer whales could use more chinook salmon,” Felleman said, referring to the declining Southern Resident orca population.