July 31, 2000
Kelly Toy and Andrew Cookson restore mussels to Upper Bear Creek.
Photo by Wendy Walsh.
A little known creature of importance in Northwest streams is the fresh water mussel, which used to inhabit all streams in Puget Sound.
It was so prolific that dense concentrations covered entire streambeds and provided a major food source for indigenous tribes throughout the year. Recently, a major effort was undertaken by a combined team of professionals to rescue mussels from a Department of Transportation project of re-meandering Bear Creek next to Redmond Town Center.The stream was originally straightened in the 1960s when the Corps of Engineers did flood control on the Sammamish River.In those days it was simple engineering with little thought to the biology of the system.
What makes this recent project unique is that it started as a mitigation for the future widening of I-520, and evolved into a major team effort of stream restoration and habitat enhancement, as well as flood control. The team included: DOT, Redmond City and Town Center officials, Washington Trout biologists, Wilder Construction, and Entranco, an environmental engineering firm, and Woodinville Water Tenders.
Bear Creek, which originates in northeastern Woodinville and Maltby, has substantial salmon runs, but populations of fresh water mussels are declining. Scientists have noted a probable relationship between healthy salmon streams and amounts of mussels, and are trying to learn more about the interconnections in the ecosystems. According to biological experts, when mussels begin to disappear, it means the ecosystem has been stressed, and is beginning to become unhealthy. Siltation and pollutants are the main sources of destruction.
Entranco contracted with Kelly Toy, a shellfish biologist and Washington Trout field biologists to salvage all the biological species in the creek area which was to be blocked off. A total of 463 mussels were transplanted to a pristine section of Bear Creek in the headwaters area.
Ralph Nelson, spokesman for Entranco says: "The area we worked in is critical to the survival of the fish passage, as it is the gateway to the Bear Creek Basin."
The project area is located in a narrow corridor between 520 and Redmond Town Center and was filled with wildlife. Eighteen beaver were moved to the higher Cascade areas, and there is still a family of deer in residence. Many birds nest here, and an indignant muskrat objected strenuously when biologists tried to move it.
Nelson, who lives in the area, originally worked on the Bear Creek Basin Plan and was aware of the sensitive nature of the ecosystem. He contacted Ray Heller, Bear Creek Basin steward, to find out what the issues were in re-meandering the stream. Heller mentioned the mussels and was amazed by the final total of numbers rescued from the project.
"I thought there would be around 60, but had no idea there would be 463," he said. "Lots of them were at least 80 years old. That says a lot about the resilliancy of the stream system, that they were able to survive in this area."
According to Kelly Toy, the mussels live over 100 years. "The age is measured by the number of lines in the shells. We know they have been around a long time as there are archeological mussel middens all up and down northwest streams, and many in Bear Creek. This indicates indigenous campsites which date back over 3000 years."
Washington Trout biologist Jamie Glasgow had a field crew working with nets along the creek to collect fish. The project had to be scheduled between July 1 and August 31 when there are the lowest populations of fish in the stream system.
Ralph Nelson remarks that Entranco works to improve habitat as a goal of most of their engineering projects. This is a major change in focus from the attitudes of 15-20 years ago. "In this project there has been intensive plantings of trees which will eventually shade the stream. Flood control is also a vital part of the project, which meant careful grading and providing channels for overflow," Nelson said.
According to Mary Lou White, of Washington Trout, these enhancement projects are still experimental. She says they are getting better at it over time, and they are beginning to see very positive results.
Fresh water mussels have become an important part of any stream enhancement because they provide important functions in the ecosystem. However, because they filter toxins, they are no longer considered edible according to those who have tried eating them. They say the mussels are better left alone. Since they are also becoming a species of concern for listing as endangered, they need to be protected.
According to Kelly Toy, who did her Masters dissertation on Bear Creek mussels, "Mussels have been declining in abundance and diversity due to habitat alterations, and water pollution."
They are not only an indicator species of the health of the ecosystem, but are "ecologically important as a food source for many terrestrial animals and improve water quality by their filtering abilities." They also help supply nutrients for other stream species.
According to biologists, we are fortunate in Woodinville to also have mussels in the Little Bear Creek stream system, which indicate that it is still healthy. Both Bear Creek streams have active citizen groups who are involved in education and protection projects.