Coldwater Habitat Restoration Project

 

Steelhead Society of BC Coldwater River Steelhead Habitat Enhancement Project
 
As- Built Summary, February, 2014
 
 
A steelhead habitat enhancement project on the Coldwater River sponsored by the Steelhead Society of British Columbia (SSBC) in partnership with DFO and PSF was completed in early 2014. The following is a project summary including an as-built report as well as interim (winter) site photos. The project provides benefit to Steelhead through improvement to streambank habitat in the Coldwater River. A series of robust rock-wood spurs were installed along a severely degraded and rapidly eroding 178 long right bank section of the Coldwater River (see photos). The site is located approximately 28 km from Merritt at the Eaton-Beaton Ranch (GPS location 49° 55.956 N, 120° 55.325 W).
Project planning for the Coldwater project was completed by January, 2013. Rock delivery was completed as scheduled by early February, 2014. Construction of the wood rock spurs was completed by February 20, 2014. The site remains in winter condition under snow cover at this time and are not fully visible. Site performance and development of key site features beneficial to Steelhead will be more evident following spring freshet. In addition, area fencing will be completed after snowmelt and ground thaw have occurred. A review of the project rationale and current site condition is provided below. Following freshet and spring to summer vegetation re-growth this site report will be updated.
2.0 Review of the Project Rationale
The Coldwater River project location was selected because it is located in an area that offers key habitat features important to Steelhead (and other salmonids) including suitable stream grade, beneficial groundwater attributes, relatively valuable up and downstream Steelhead habitat. In addition an extensive, groundwater and river fed off-channel site previously constructed by DFO to enhance juvenile salmonid habitat adjoins the Coldwater River immediately upstream from the restored site. In addition, the site is located on a ranch isolated from high public traffic, set back from Coldwater Road access. A wide river floodplain area exists on the right and left banks from the restoration site. The right bank adjacent to the restored habitat has minimal agricultural use and relatively healthy riparian vegetation and the landowner has agreed to livestock exclusion fencing for riparian area enhancement.
The Coldwater River habitat enhancement site provided an opportunity to combine natural local features with some constructed ones to create year round improvement to
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key Steelhead habitat values such as low human traffic, high quality groundwater upwelling combined with controlled off channel stream flow from the Coldwater River to extensive off-channel habitat, suitable gradient and substrate features, relatively healthy up and downstream riparian areas and connectivity to other nearby suitable steelhead spawning and rearing habitats.
3.0 Description of Construction Process
Construction was undertaken in February, 2014 at low flow, prior to spring freshet. In total 58 loads of rock, 24 large wood debris units and 1855 cuttings were utilized in constructing a series of 15 wood rock spurs to stabilize 178 linear meters of streambank and riparian area. The rock supplied was comprised of 0 .3-1.5m boulders with a high proportion of larger rock size in the mix (see photos).
Once the rock was delivered construction began by installing spurs 1-5. Spurs 1-5 were installed relatively close together (averaging 11 m spacing) along the uppermost 43 m of the site, where the curvature in river meander bend was greatest. Spurs 6-15 were installed relatively farther apart (averaging 14 m spacing) along the lowermost 128 m of the site, where the curvature in river meander bend was lessened.
The uppermost spurs (spurs 1-5) were each comprised of approximately 24 m3 of rock and 1-2 large wood debris units with 75 cuttings. The lowermost spurs (spurs 6-15) were each comprised of approximately 32 m3 of rock and 1-2 large wood debris units with 150 cuttings. A setback rock spur with large wood debris was installed at each of the 15 spur locations, keyed into the river bed.
Cuttings were added to the upper depths of the excavation. Gravels and soils were place in the upper bank above high water mark. Winter dormant black cottonwood cuttings as well as various rooted species including alder, rose and snowberry that were salvaged during excavation were planted at the site. A recessed, keyed low profile 7 m rock toe was installed to tie into the existing bank, downstream of Spur 15. Disturbed areas were re-contoured and winter seeded with grass seed on bare exposed ground even though it was still snowing at the time.
4.0 Description of Constructed Features
The right bank stabilization installations have created high complexity river edge which will stabilize the bank from further erosion. The installed structures are expected to scour but remain stable with spring fresher and begin to naturalize rapidly following freshet to offer adult and juvenile habitat preferred by Steelhead. Small scour pools with overhanging vegetation, boulder and wood surface microhabitat are expected to provide cover, hydraulic variability and leaf litter drop as well as shade and improved benthic community structure that will benefit Steelhead.
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5.0 Summary
As of February, 2014 the streambank stabilization structures appear to be well installed and functional. Project effectiveness will be more evident following loss of snow cover, and a spring freshet event, after which performance will be re-evaluated and site naturalization features identified. An onsite review and updated photoset will be obtained as site features such as scour pools and riparian vegetation development continue to naturalize and will be reported on a one year post construction site assessment.