Silverhope Creek Mainstem Restoration
The goals of this project were to: a) accelerate the natural recovery of riparian vegetation by creating habitat structures that play a key role in bank stabilization; b) re-establish high quality juvenile salmonid mainstem habitat; and c) increase stream habitat characteristics and productivity to provide greater smolt-yields.
Historical road development and logging activities in the Silverhope watershed have resulted in significant impacts on aquatic habitat over past decades. The Silver-Skagit Forest Service Road runs parallel to Silverhope Creek from Hope to Ross Lake State Park (United States).
The reduction of natural stream structure development in the form of natural log jam accumulation, and associated river meander patterns have prevented pools, riffles, and runs, which are highly utilized by juveniles, from being developed. This freshwater habitat degradation is believed to be a contributor to the declines in steelhead and char populations within this watershed.
The mainstem placement of anchored woody debris fish habitat structures will benefit the ecosystem by providing localized stream depth from associated scoured pool development, hydrological protection during floods, and enhanced gravel storage amongst the structure. The collection of organic matter will also provide a host for invertebrate community growth, improving food/energy resources for juveniles to sustain the harsh fall/winter/spring river environment.
The focus of the 2008 stream rehabilitation work has been a one kilometre reach, located between road kilometre marker 14.5 and 15.5. The rehabilitation ties into two kilometres of previous restoration work, which was completed over the past three years immediately downstream. A total of 10 large woody debris habitat structures were proposed in the 2008 restoration plan, though a total of 13 woody debris restoration units were actually implemented. This included: 11-triangulated habitat structures; 1-single log habitat unit; and 1-parallell habitat structure. A total of 36 coniferous trees/logs were used, and were on average 15m in length, and 0.5m diameter at the butt end (not including the width of the rootwad).