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Location: Cariboo-Chilcotin, Horsefly River Valley Project Summary
SUMMARY We are proposing to eliminate a fish stranding issue and to enhance habitat for juvenile Coho salmon on Patenaude Creek. Both of these actions are required because of past land management practices. We will deactivate an abandoned irrigation system thereby severing the connection between this creek and a rearing channel that is acting as a fish trap. We will also rebuild and complex the channel of Patenaude Creek, thereby enhancing its value as salmonid habitat. DESCRIPTION Declines of Coho salmon are well documented throughout the range of this species. In particular, Coho stocks from the Interior Fraser appear to have declined at a greater rate than Coho from other areas (COSEWIC 2002). Declines have been linked to a variety of causes, one being human disturbance of fresh water habitats (COSEWIC 2002). In terms of sustaining Interior Coho, it is believed that productive freshwater spawning and rearing habitats are important components of the life history of this species, particularly during times of adverse marine conditions or high fishery exploitation rates (DFO 2005). Indeed, the recovery potential of Interior Fraser River Coho is linked in part to freshwater habitat conditions. Furthermore, the identification of viable habitat protection and watershed restoration activities is recognized as an important part of the management of this species (DFO 2005). Coho are found in numerous streams within the Horsefly River watershed. McKinley Creek, a tributary of the Horsefly, has been identified as one of the most productive (and well studied) streams in the Fraser River system (Holmes 2009). Other, smaller creeks have also been identified as both a habitat for spawning and rearing Coho. Some of these streams represent candidate sites for enhancement and/or restoration, while others represent significant, if not insurmountable challenges from a restoration perspective. For example, Black Creek has been significantly altered due to hydraulic mining in the past and consequently represents an extremely challenging restoration project. A perched culvert on Wilmot Creek confines Coho to 150 m of habitat below the culvert. Because of its location on the Black Creek Road (at the bottom of a hill and on a corner), and because of the amount of traffic (commercial logging, and recreational vehicles) replacing this culvert would be extremely expensive and difficult logistically. Patenaude Creek, a tributary of the Horsefly that runs through the Horsefly River Riparian Conservation Area (HRRCA) that is owned and managed by TLC, on the other hand, represents an excellent candidate site for restoration and enhancement work. Recent work by a graduate student at UNBC (Warren 2010) and follow-up work by DFO (Hillaby 2009 and 2010) has noted that Patenaude Creek represents valuable year round rearing habitat for juvenile Coho salmon. In addition, it is easily accessible, and has valuable habitat that is not limited due to upstream barriers. In addition, this restoration project would not involve any road construction work. Furthermore, all of the restoration work would be completed on land that is, and will continue to be managed as a protected area, thereby ensuring the longevity of the project. Like many creeks that have been a part of an old agricultural operation, Patenaude Creek has undergone significant modifications, the most obvious being physical straightening such that a section of the creek is actually physically perched above the adjacent flood plain. Detailed survey and fish sampling work by DFO in 2010 has discovered that there is an abandoned flood irrigation system on the creek. The remnants of this system (dead ends of irrigation channels and the elevated nature of the creek bed) are causing the creek to overflow it banks at high water and, and a result is leading to the transportation of juvenile Coho to a rearing channel that was built in 1999 for the benefit of rainbow trout. This fish sampling has also noted that juvenile Coho salmon were found trapped and likely died at the terminal end of this rearing channel. In addition, the creation of this old irrigation structure has also significantly reduced the amount of in-stream rearing habitat for Coho, and hence is likely limiting the production of Coho in this creek. Thus it is apparent that past land management undertaken on this site has resulted in a fish stranding issue and a decrease in the habitat quality and hence productivity of a potentially very productive Coho creek. This project is designed to address both of these past land management issues. We intend to eliminate this stranding issue in two places. First, we will consolidate the flow of Patenaude Creek by closing off dead end irrigation channels, thereby preventing Patenaude Creek from flowing into the adjacent rearing channel. We will also reconstruct channel reaches to maintain a suitable stable channel grade and length that is not perched above the surrounding ground. Second, we will excavate low parts of the rearing channel near the terminal end of the pond such that down-stream fish movement is facilitated. Concomitant with this will be the improvement of fish habitat within Patenaude Creek itself. We will re-establish channel complexity by installing large woody debris and other structures. This work will both increase in-stream habitat for juvenile coho and stabilize the stream channel itself. The end result will be that Patenaude Creek will more closely resemble its historic channel and empty entirely into the Horsefly River. An additional benefit of consolidating the year-round the flow of Patenaude Creek will be the reduction in the potential for winter salmon mortality
METHODS Rearing channel modifications The rearing channel that was previously constructed often strands fish due to the depth the original channel was excavated relative to the Horsefly River stages and groundwater levels. The channel has been surveyed to identify these high points relative to groundwater and surface water levels. From this information, these high points will be lowered to ensure continuity for fish passage and prevent future stranding. Where it will be feasible additional habitat structures will be placed in the channel. Work on Patenaude Creek There are many areas where Patenaude Creek escapes the currently defined and perched channel. To return the channel to a more natural profile, the concept is to undertake a combined approach: * to fill the areas where the channel currently is not contained with in its banks and; Actual location of confinements and realignments will be confirmed during the design process, which will also include final ground truthing before construction. Any remnant irrigation ditches through the fields that are under groundwater influence will either be graded to passively ensure fish passage as flows recede, or will be fully decommissioned. The method selected will be based on the specific to the ditch alignment in the field relative to Patenaude Creek, Horsefly River and rearing channel to ensure maximum benefit for the fisheries resource. These plans are currently being developed by DFO engineers and restoration biologists. Any areas disturbed through the modifications made to consolidate flows and improve connectivity for fish will be seeded and planted with species appropriate for the site. In-stream and in-pond work will be conducted at low flow (Spring 2011). Subsequent monitoring will confirm the success of the modification in preventing stranding as well as overall fish utilization of the area. BENEFITS This project has significant benefits for Interior Coho salmon. Presently, McKinely Creek is a productive creek for spawning Coho. There are other creeks within the valley that also represent valuable habitat for this species. Of these, Patenaude Creek represents an excellent candidate stream for restoration and enhancement work. With this work we will be able to eliminate a fish stranding issue and increase the available habitat for Interior Coho. Both aspects of the project have significant tangible and likely immediate benefits for Interior Coho salmon and hence the overall sustainability of Fraser River salmonids.
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