The Skokomish Tribe and the Mason Conservation District have relocated a small tributary to the Skokomish River that has suffered water quality and salmon habitat problems for decades.
The simple redirecting of Weaver Creek created much needed floodplain and streamside habitat for salmon, said Joseph Pavel, the tribe’s natural resources director.
Weaver Creek used to empty into the southern oxbow curve of the Skokomish River in the early 20th century. In the 1940s, the river was straightened to aid navigation, disconnecting it from the creek.
At the time, a new channel was excavated to reconnect the creek to the river, but without the original functions such as proper gradient and water flow that salmon need.
As a result, a sediment plug formed in the new channel, creating water quality issues for salmon for decades, such as standing water in the creek and low dissolved oxygen levels.
“The old channel would have served as rearing and refugia habitat for multiple species of fish throughout the year but because the water was stagnant, the conditions were lethal to fish in the summer, and fish access was limited during certain flows,” said Evan Bauder, the conservation district’s habitat program manager.
To fix the problem, in 2017 the tribe and conservation district created a new channel redirecting Weaver Creek to nearby Purdy Creek, bypassing the sediment plug, installed 25 logs for salmon habitat and established a 100-foot riparian buffer on both sides of the new channel. Native vegetation was planted along the banks and in an adjacent former farmland to expand the floodplain.
“Now the cold water from Purdy Creek is flowing in there, so the area should be a viable rearing area since the water quality issues are fixed,” Bauder said.
“The mounds we created near the banks using the excavated material from the new creek channel establishes higher ground that will support conifers in the floodplain,” Pavel said. “This increases floodplain complexity and reduced project costs because we didn’t have to transport and dispose of the material.”
This kind of restoration improves the riparian habitat function that salmon need to survive, including shade from trees to keep water temperatures cool, preventing streambank erosion which can smother fish egg nests, and provides recruitment of prey and nutrients to the stream.
This project builds off other efforts in the valley, such as building a new salmon-friendly bridge over Purdy Creek to help with the overall effort to improve salmon habitat in the Skokomish River valley.
The redirected Weaver Creek, left, now flows into Purdy Creek. The Skokomish Tribe and Mason Conservation District also installed logjams and planted native vegetation to improve salmon habitat. Photo: Mason Conservation District