Commercial property construction in Woodinville was nearing completion when the owner discovered that water outflow from the project was eroding an adjacent creek. As a result, The State Department of Fish & Wildlife required restoration of the exposed stream to mitigate negative construction impacts and accommodate future fish habitat. That’s where we came in.
The stream bordered an upward-sloping lot filled with sticker bushes which led up to the construction site. Water diverted from the construction area had caused an increase in water flow down to the creek, gradually deteriorating the banks and filling the stream bed with soil. A plan was created to reclaim the stream’s original footprint by temporarily rerouting the creek flow, then manually rebuilding the stream bed and its banks.
Eroded stream bed and banks (click to enlarge photo)
Our fist order of business was to dam the creek and reroute the water to a culvert upstream of our work area. Once this was accomplished, the real work began.
Along the adjacent slope, we cleared invasive sticker bushes and replaced them with over 1000 native plants. Establishing and encouraging new root growth was essential to preventing future erosion, as water levels increase/ decrease seasonally and as a result of future construction in the area.
To create the new stream bed, we spread 95 tons of cobble and boulders, emulating a naturally-occurring habitat while allowing ample air and water flow for fish and wildlife. In one section we added a 24-inch log drop, creating a pool to stimulate oxygenation of the water flow.
Rebuilding stream bed
Back on the flanks of the creek, we installed an earth- and sand- bag retaining wall to reinforce the creek banks as the plantings took hold. Coconut fiber blankets were laid to stabilize the slopes from erosion.
Sandbag installation and placement of log drop
We inserted live cut willow branches into the fabric at regular intervals. Once established, their roots will help stabilize the stream bank to reduce erosion. Growth of the trees will provide much-needed habitat and shade for native animal species.
Closer view upstream at log drop
When the restoration was completed, we undammed the creek and released the water back downstream. Water flowed smoothly and as anticipated. Our project was a success, leaving the commercial property owner and the Dept of Fish and Wildlife satisfied that business as usual could proceed.
Release of water back into stream & view looking upstream
Views of the Little Bear Creek today, after the willow trees and plantings have become established. Water now flows smoothly through this restored habitat with no worry of erosion of the stream banks and protection from future construction impacts.
Looking upstream today, with log drop in background
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