The Site C Channel Contouring and Side Channel Enhancement Project is an innovative project designed to mitigate impacts on the aquatic environment, with emphasis on fish habitat, in the Peace River, downstream of the Site C Dam. Since it began, the enhancement Project has moved roughly 1.7 million cubic meters of river material and is the largest fish habitat project undertaken by BC Hydro. This submission focuses on one component, Site 107R, which created 6.5 ha of new aquatic habitat and was completed in the summer of 2024.

Site 107R is located 1.5 km downstream of the Site C Clean Energy project and is designated into two work areas, the 107R Main Channel Bar and the 107R Side Channel. The design objectives included establishing hydraulic connectivity in a relic channel, from the main channel to the south channel, to create approximately 1.6 km of permanently wetted side channel habitat. The in-river works were designed to decrease the wetted area between selected minimum and maximum operational flows, reducing the areas that dewater and potentially strand fish and increasing available habitat for fish throughout the operational flows downstream of the Site C project. Excavated material was used to infill depressed areas, allowing for an overall balance in the project’s cut and fill requirements. The work at Site 107R also included the installation of large woody debris structures along the habitat channel banks, designed to provide habitat complexity and cover for fish.

This project involved a multidisciplinary team of professionals from concept through to construction and required collaboration with many departments within BC Hydro, stakeholders, Treaty 8 First Nations and federal and provincial regulatory agencies, all of whom were key players in the successful delivery of the Project.

NHC’s engineering designs used TELEMAC-2D, a hydrodynamic modelling software program that estimates water levels and velocities based on digital geometric meshes of the river valley developed from LiDAR, and bathymetric data collected by NHC and other parties. Operational flow ranges were modelled and the results were used to design stable habitat configurations with materials limited to those available on-site, and engineered to generate velocities navigable by fish and of sufficient hydraulic complexity to simulate natural flow patterns desirable to other aquatic species.

During the construction phase of the project, NHC provided the contractor with digital terrain files of the design surfaces, allowing GPS instrumentation onboard construction equipment to guide construction, eliminating the need to conventionally stake-out workpoints and allowing construction conformance checks to be completed in real-time.

Given the dynamic nature of the site, construction engineering methodology required an adaptive approach to manage changing site conditions. Nevertheless, construction continued without disrupting native terrestrial and aquatic animal spawning, hatching and nesting patterns, and work was conducted without inhibiting bird nesting. Construction in the winter was another challenge; however, it was also used as an opportunity to construct areas from the frozen ground that would have otherwise been difficult due to the soft saturated soils present during the summer months.

NHC’s expertise in geomorphology, ecohydraulics, hydrodynamic modelling, hydrotechnical engineering, and construction engineering developed 6.5 ha of aquatic habitat downstream of the Site C Clean Energy Project. Approximately 1.6 km of permanently wetted side channel habitat was created that included large woody debris structures designed to provide habitat complexity and cover for fish. Ongoing monitoring has also shown that the new habitats are being used as predicted by many fish species.