Northwest Pipeline LLC - Stream Restoration
48 NORTH supported Northwest Pipeline LLC (Northwest) with restoration of a tributary to Walker Creek in Skagit County, Washington. This project addressed the fish passage barrier created by an exposed natural gas pipeline bisecting the channel of this tributary.
Working from the conceptual design through to obtaining the required permits, we provided Northwest with planning and mapping services, as well as biological survey support including Ordinary High Mark and wetland delineations.
Once we established the baseline conditions, 48 NORTH worked closely with regulatory agencies throughout the environmental permitting process to reach acceptable solutions in an expedited manner. Our team supported the engineering lead with their in-stream designs as to adhere to the regulatory design guidelines and criteria. Ultimately, the goal of this restoration project was to provide an ecological uplift by removing the fish passage barrier (the exposed pipeline) and reducing bank erosion. As an added benefit, this project increased the tributary's habitat complexity and restored floodplain connectivity by reconnecting the hyporheic zone between the riparian wetlands and stream.
Upon construction, 48 NORTH supported the long-term, post-construction monitoring effort for this project.