Reliability of the Nechako Reservoir to meet hydropower production and fisheries needs under climate change

The adverse impacts of water regulation and reservoir operations on fish habitats is well documented. Consequently, many reservoir operators are required to satisfy environmental flow objectives intended to mitigate these impacts. However, changes in flow seasonality due to climate change may affect the ability of reservoir operations to satisfy hydropower commitments and environmental flow needs. On a regional scale, climate change is projected to alter the timing and volume of water availability over Pacific Northwest America with an earlier freshet, higher winter precipitation, lower summer flows and increased water temperature. However, impacts are specific to each system, and in this talk we will evaluate how water cycle changes could impact the Nechako Reservoir’s reliability to meet hydropower generation commitments under safe operating conditions, and satisfy fisheries conservation requirements. The Nechako Reservoir was created in the upper Nechako River in 1950’s to generate power for an aluminum smelter on the coast of British Columbia. Following concerns over the negative impact of the reservoir operation on salmonid habitats in the downstream Nechako River, the Nechako Fisheries Conservation Program (NFCP) was established in 1980’s to protect chinook and sockeye salmon populations by enforcing an environmental flow management schedule. Using a multi-model ensemble of CMIP6 climate projections, climate change is projected to have little to no influence on the reliability of the reservoir to satisfy hydropower generation commitments. However, a carry-over storage trend is projected that would compromise the reservoir safety without larger water releases. The effectiveness of the Summer Temperature Management Program, which uses reservoir releases to moderate high water temperatures during the sockeye migration period, is also likely to be limited in the future.

Bio:

This talk will be delivered by Dr. Samah Larabi, Hydroclimate Scientist at the Pacific Climate Impacts Consortium.