Construction Activities

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Filling the reservoir

One of the last steps in building Site C is to fill the reservoir, which allows us to put the generating station, spillways, turbines and generators into operation, creating enough energy to power the equivalent of about 450,000 homes per year in B.C. Site C will generate about 35% of the energy of the W.A.C. Bennett Dam, with just 5% of the reservoir area.

Reservoir size comparison

The Peace River will widen by two to three times

  • Covers 5,550 hectares of land, with a total surface area of about 9,330 hectares.
  • 52 metres deep close to the dam, 36 metres deep at Halfway River, and 18 metres deep near Hudson’s Hope.
  • 83 kilometres long and two to three times the width of the current Peace River.
  • It will take four months to fill the reservoir


Reservoir filling could begin as early as fall 2023

To meet our projected in-service date of 2025, Site C reservoir filling could begin as early as fall 2023, or as late as fall 2024. Before filling the reservoir, the following must be complete:

The diversion tunnels need to be closed beforehand

Reservoir size comparison
Prior to filling the reservoir, four large orifice rings are installed in the diversion tunnels to restrict the flow of water in a process called conversion.

Prior to filling the reservoir, we must first convert (or close) the diversion tunnels that are currently in service to divert the Peace River to allow for construction of the earthfill dam. Conversion of the diversion tunnels requires installation of constrictions (or orifice rings) inside one of the tunnels to restrict the flow of water during reservoir filling.

This conversion work must occur between July and September due to environmental, operational, and weather-related constraints as well as construction progress. This means the window to safely fill the reservoir will start and complete in late summer or early fall.

While filling the reservoir is one of the last activities require to complete the dam, clearing the area began years in advance. We have removed trees and vegetation from the dam site and the reservoir area to ensure boater safety and reduce impacts to dam construction and operations.

Reservoir clearing and debris management activities continue through 2023. This includes road construction, logging, hauling timber to local mills and waste wood burning.

We recognize the importance of this final step, and the impacts on local communities and Indigenous peoples. We’ll continue to communicate expected changes and timing of reservoir filling before it begins with our all stakeholders in the Peace Region, including local government, residents and Indigenous groups.

Prior to filling the reservoir, more than 20 regulatory approvals must be met. In addition to these authorizations, reservoir filling must consider BC Hydro’s operation of the Peace River system, both up and downstream impacts, environmental and weather constraints, as well as the construction progress.


Learn More

 Filling the reservoir factsheet PDF  1.5 MB