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Filling the reservoir

One of the last steps in building the Site C dam is to fill the reservoir. Reservoir filling will take about four months, widening the Peace River by an average of two to three times.

Tunnel conversion is complete

Reservoir size comparison
Prior to filling the reservoir, we install four large rings in one of the diversion tunnels to restrict the flow of water.

Tunnel conversion, a key step in preparing for reservoir filling, is now complete.

Since 2020, two tunnels have been diverting the Peace River around the dam site to allow us to build the earthfill dam.

We started the process of tunnel conversion in June 2023. Over the course of 12 weeks, we installed four large rings inside one of the tunnels to restrict the flow of water once reservoir filling begins.

Tunnel conversion needed to take place between July and September due to environmental, operational, and weather-related constraints as well as construction progress.

Converting the tunnels helps control the flow of water

Once we decide to fill the reservoir, water will be restricted in the tunnels, causing the water level to rise. When the water is high enough to flow through the spillway, both tunnels will close.

Flows downstream will continue throughout reservoir filling. The diversion tunnels will be permanently sealed and filled in after reservoir filling is done.