Letter: BC Hydro clarifies Revelstoke 6 river flow impact

BC Hydro responds to concerns about impact of adding sixth turbine to Revelstoke Dam on downstream ecosystems.

Crews install the fifth penstock at the Revelstoke Dam. Planning is underway to install the sixth and final turbine at the dam by 2021.

Editor,

Thank you for the opportunity to provide some further information on BC Hydro’s Revelstoke Dam operations and potential changes we expect may result from the addition of a sixth generating unit.

Revelstoke Generating Station is typically operated as a daily peaking plant, where the available water is used to maximize generation when load demand is high. Generation is reduced during light load hours to a minimum flow of 5,000 cubic feet per second (cfs). Maximum discharge from the facility through the five currently installed generating units is 75,000 cfs. However BC Hydro can release more water from the facility if needed for flood control by releasing additional water over the spillway.

With the additional capacity from a new sixth generating unit at Revelstoke dam, BC Hydro will use the existing water supply differently. At high demand periods with all six units operating for short periods of time, up to 24% more water (up to 93,000 cfs) could be released. However just like a car engine, generating units are less efficient when operated at full capacity so we expect to only be at full power output (and maximum generation discharge flow) less than one per cent of the time.

Because the amount of water available for power generation will remain the same, the addition of the sixth generating unit is expected to only change how the water is used on a day to day basis. BC Hydro has conducted detailed modelling work to understand how the operation of our Columbia facilities will change with six generating units at Revelstoke Dam.

When compared to the operation with five generating units, Revelstoke Dam with six generating units is expected to discharge higher flows between approximately 60,000 and 75,000 cubic feet per second somewhat more often (about 11 per cent of the time compared to about three per cent of the time currently). The facility is expected to discharge medium flows (between approximately 35,000 and 60,000 cfs) somewhat less often and low flows (less than 35,000 cfs) about the same. Flows are expected to be above 75,000 cfs occasionally, less than one per cent of the time.

The Environmental Assessment Office (EAO) is conducting an environmental review of the Revelstoke Unit 6 Project. As part of this process, BC Hydro will submit an application for an Environmental Assessment Certificate that assesses the incremental impacts of the sixth generating unit.

The application will include mitigation and monitoring measures to address project effects. Currently the EAO is soliciting public feedback on the draft Application Information Requirements, a key document for the review that outlines the specific information that must be included in BC Hydro’s application. The public comment period on this document ends June 20, 2016. The public will have another opportunity to provide feedback to the EAO after we submit our application.

Please feel free to get in touch with me at 250-814-6645 or Jennifer.walker-larsen@bchydro.com if you have any questions about the Revelstoke Unit 6 Project or BC Hydro’s Columbia operations or would like to join our mailing list for project updates.

Sincerely,

Jen Walker-Larsen

BC Hydro, Revelstoke