Hansen Creek Tributary Restoration
The Hansen Creek Tributary Restoration is an effort that resulted from mitigation associated with the Williams’ Northwest Pipeline Corporation’s Evergreen Expansion Project. During the development of the Northern State Hospital, in Sedro-Woolley, WA, a tributary to Hansen Creek (shown on the map below as Trib. #272) was diverted from its original channel into a narrow ditch that ran directly into Hansen Creek several hundred feet upstream of the original confluence. The mitigation project removed the upstream earthen diversion and installed a series of three weirs in the ditch line. The new tributary consists of 1,200 feet of original channel and roughly 300 feet of constructed channel that re-connects the tributary to Hansen Creek. Nearly 600 conifers and shrubs were planted shortly after the completion of the constructed channel and bridge emplacement.
Map of restoration activities at Hansen Creek and Tributary #272.
Project Status/Timeline
The project is in its fourth year of monitoring, in which the survival rate and natural regeneration of the installed plants, the condition of the installed weirs, and the control of invasive species (Himalayan blackberry, butterfly bush and scotch broom) are being tracked within the project area. The site was used for an electro-fishing class in the spring following construction, during which numerous coho salmon and trout fry were collected in the lower end of the newly constructed tributary. During winter site visits, active coho spawning has been documented in the tributary.
Riparian planting at Hansen Creek.
Planting included native species such as snowberry and western red cedar.
Channel habitat at Hansen Creek.
Primary Project Contact
Brenda Clifton
Funding Sources
Williams Northwest Pipeline Corporation
Project Partners
Washington State General Administration, North Cascades Gateway Center (property administrators)