Friday, December 31, 2010

Willows Creek After Restoration

Logs and "el-wood" are positioned in Willows Creek
Earlier this year, the City implemented a plan to restore a 800 foot section of Willows Creek to a more natural state.  The creek originates in the Rose Hill watershed of Redmond and empties into the Sammamish River about a half mile north of the 90th Street Bridge.  Migrating salmon gather in the mouth of the creek to find cool water and shade.

Erosion and a significant sedimentation problems occur during periods heavy rains.  The problem is augmented by a stormwater outfall servicing the surrounding roads and homes.  High flow rates reduce the amount and quality of habitat for salmon and cutthroat trout. According to Tom Hardy, city stream specialist cutthroat are present but not salmon.  Read more...

Tom Hardy led a stream restoration project carefully positioning ~100 pieces of large woody debris (logs and branches) across the creek.  (Most of the native logs were removed years ago for salvage by loggers.)  The City paid the Washington Conservation Corps to do most of the labor.
According to Mr. Hardy:
"This reach of Willows Creek was identified by City staff for this project because of its low-cost, significant, protected riparian buffer and its potential to provide spawning and rearing habitat for salmonids."
Nine Red Alder and one Big Leaf Maple were felled at chosen points along the upper section of the creek.   Selective tree thinning speeds up forest succession.  The native logs were supplemented with imported Douglas fir and Cedar logs.  Some logs were bundled into "el-wood" (engineered large woody debris). The "el-wood" were joined together on site to replicate log jams.

Logs slowed stream flows by creating "little dams,"  Small pools, eddies and sedimentation traps form. In addition, little cascades oxygenate the water. All of these effects provide better "living quarters" for fish, resulting in improved survivability. The project called for planting 100 Cedar, Spruce, and Fir trees in the riparian for shade, cooler water, bank stabilization and wildlife habitat.

by John Reinke and Bob Yoder
Photo by Reinke

Sources:  Public Notice, Water Tenders, Letter and emails from Tom Hardy, tour by Tom Hardy (Yoder and Reinke). 

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