Snohomish R Confluence Reach Restoration

Snohomish County used this funding for a reach scale restoration effort, on three miles of the Snohomish River, downstream from the confluence of the Skykomish and Snoqualmie rivers. . Recognizing the importance of this area to Chinook salmon and other salmonids for spawning, rearing holding and migration, the Snohomish Basin Salmon Recovery forum identified it as a focus area in the Near Term Action Agenda (SBSRF, 2002).

The project used a phased approach, with activities at three different project sites, 1) Bob Heirmann Wildlife Park, 2) Twin Rivers Park and 3) Crabb Bend. We pursued the following activities:
• Planting with 12-15 ft. tall trees and cottonwood posts.
• Placement of LWD
• Construction of LWD complexes
• Reconnection of side channel
• Final design of dike breaches
The dike breach design work, placement of LWD, riprap removal, and side channel reconnection work is based on an analysis of the reach conducted by Snohomish County and included 2-D modeling of the reach.

During and following construction activities, two dikes in the area were analyzed for the position and magnitude of possible dike breaches. As luck would have it, during the November 2006 flood event on the Snohomish, one Dike breached in the location where the hydraulic model had predicted the maximum amount of sheer stress. Funding has since been secured to complete the dike breaching, which will eventually return much of the area to fully functioning riverine condition.

During the latter part of construction of the Twin Rivers side channel, an opportunity arose to assist with the installation of a substantial flood fence on the Skykomish River at Groeneveld Slough. Approximately 980 cottonwood boles were placed, and during the many high water events since that time, they have successfully withstood removal and have racked up a great deal of woody material, as designed

The goal of the project is to restore native riparian vegetation along salmon bearing streams. The objective of the project is to restore natural streamside vegetation, improve stream temperature, reduce erosion, filtration, and recruit large woody debris.