ESSA led the modelling and assessment of aquatic ecosystem impacts for the environmental assessment of the proposed Site C dam on the Peace River, working together with specialists from Golder (water quality modelling) and Limnotek (field studies of primary and secondary productivity).
BC Hydro proposes to develop a dam and hydroelectric generating station on the Peace River, referred to as the Site C Clean Energy Project. The dam would be an earthfill structure approximately 1050 m in length and 60 m in height above the riverbed. The new reservoir would be 83 km long, with an area of 93.1 km2.
The approach to assessing impacts on the aquatic ecosystem involved multiple lines of evidence and multiple linked models, anchored in empirical information from both the Peace River and existing reservoirs in British Columbia. The linked models (including geomorphic, water quality, single species models to assess fish passage options, empirical models of benthic biomass and Ecopath food web models) were combined to provide predicted changes in biomass for different ecosystem components both upstream and downstream of the proposed dam.
The inherent uncertainty in future predictions was accommodated by using 18 different model scenarios, spanning a range of assumptions for primary production and fish population responses.
ESSA staff were closely involved in writing the environmental assessment, providing responses to government agencies and First Nations on details of the analysis, giving testimony at the Joint Review Panel hearing on the environmental assessment, and designing post-project monitoring plans, including statistical power analyses for key fish population hypotheses and indicators.