The effect of reservoir operation on circulation, turbidity and productivity in Carpenter Reservoir, BC

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This project examines Carpenter Reservoir, the key component of the Bridge River hydroelectric system - B.C. Hydro's third largest - located between Whistler and Lillooet in south-west British Columbia. Inflows to Carpenter Reservoir are high in finely ground rock particles (glacial flour) which are slow to settle, and which give rise to water with a characteristic milky (turbid) appearance. High glacial turbidity limits the penetration of light, which can reduce algal growth and, in turn, limit fisheries productivity.****Our long term goal is to understand the effect of changes in reservoir operation on the ecological productivity of the reservoir and the effect on downstream water bodies. The short term goal is to understand the effect of changes in reservoir operations on turbidity, temperature, nutrients and primary productivity in Carpenter Reservoir. Changes in reservoir operation will include high flows to meet demand in electricity markets, extremes in climate such as a winter with a high snow pack, and long term trends such as reduced glacial melt.****To address this question, we will collaborate with Limnotek Research and Development Inc. We plan to use a combination of field data and computer modelling. A widely used reservoir model, CE-QUAL-W2, will be used to determine the effect of a range of reservoir operation scenarios on turbidity, light, temperature and nutrients, and these factors will then be used to estimate primary productivity in the reservoir. The physical processes underlying the modelled changes in productivity - such as plunging inflows, light limitation, nutrient transport, temperature stratification and residence time - will be examined in detail. The project will benefit BC Hydro in understanding the ecological function of Carpenter Reservoir, and provide the understanding needed for water use planning to effectively balance optimal power production against social and ecological values. ************