Snohomish County’s freshwater mussel die-off worries stream advocates

Freshwater mussel populations are in steep decline in streams in urban Snohomish County, experts say.

Mussels are mostly stationary and sift through water for food, a filtering process that pulls pollutants from the water.

However, they can only filter out so much, said Ardent Thomas, a University of Washington researcher form the School of Forest Resources.

“Between 2002 and 2007 there was a 93 percent die-off of fresh water mussels in Bear Creek downstream from Paradise Lake,” he said.

Similar die-offs are happening in other heavily urbanized streams, he said.

That decline is an indication that salmon, aquatic insects and other species dependent on healthy waterways also could be in trouble, said Dick Schaetzel, a past president of Water Tenders, a nonprofit group working to restore and monitor Bear Creek, which flows from Snohomish County to the Sammamish River and Lake Washington.

“They’re kind of like the canary in the coal mine in streams around here,” Schaetzel said.

If they’re in a stream, it’s a very healthy stream. If they’re gone, everything is dying, he said.

Schaetzel is scheduled to give a talk about the importance of freshwater mussels at 7 tonight at the Everett-based Adopt-a-Stream Foundation at the Northwest Stream Center, 600 128th St. SE, Everett.

“To date, nobody really knows what is causing this decline,” Schaetzel said. He said its likely a number of factors, including elevated pollution levels, warming stream temperatures and too much sediment in the streams.

The Adopt-a-Stream Foundation invited Schaetzel to spread the word on what is a worsening problem, said Tom Murdoch, the group’s executive director.

“This is an opportunity for people to lean more about the aquatic life in local streams,” Murdoch said. “Freshwater mussels are an integral part of stream ecosystems. And right now they’re in trouble.”

The role mussels play in filtering pollutants out of the water shouldn’t be overlooked, he said.

“They’re always sucking in water,” Murdoch said. “They’re filter feeders. They’re the kidneys of streams.”

Reporter Lukas Velush: 425-339-3449 or lvelush@heraldnet.com.

Discover mussels

A lecture on freshwater mussels of the Pacific Northwest is scheduled for 7 to 8:30 p.m. today at the Northwest Stream Center, 600 128th St. SE, Everett.