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Coquitlam-Buntzen Diversion Tunnel

Water Level Changes in the Coquitlam River and Buntzen Lake

In January and February 2023, we may need to release more water than usual from the Coquitlam Reservoir to the Coquitlam River as we work to upgrade the tunnel. There may be higher than normal flow and water levels in the river during this time. We ask that the public be extra careful when active around the river since water levels can rise and fluctuate without warning.

Water levels at Buntzen Lake may be affected throughout the tunnel outage from January to July 2023. Users are asked to exercise caution and obey safety signs and barriers.

Image of the Coquitlam-Buntzen facilities

In 1902, the Coquitlam-Buntzen facilities comprised of the Coquitlam Dam, the Coquitlam Diversion Tunnel and Lake Buntzen 1 Powerhouse were built to provide electricity to the city of New Westminster. 

The 3.9-kilometre Coquitlam Diversion Tunnel was built and later expanded between 1909 and 1911, to divert water from the Coquitlam Reservoir to Lake Buntzen Reservoir to generate electricity at the Lake Buntzen 1 Powerhouse. The tunnel is also used to control the water level of the Coquitlam Reservoir which provides water for Metro Vancouver and help maintain Buntzen Lake’s water levels for recreation.  

What we’re doing

We’re replacing the three gates in the tunnel that are used to control the flow of water through the tunnel to bring them up to modern-day standards and seismic operability. We’re also installing new control equipment to allow for remote monitoring of the facilities.

Why we’re doing it

The last major update of the Coquitlam-Buntzen facilities was completed in 1955. To ensure continued reliability of the tunnel so that water can continue to be safely transferred from Coquitlam Reservoir to Buntzen Lake, we’re addressing near end-of-life equipment inside the tunnel.

Communities affected

The Coquitlam-Buntzen facilities are in the City of Coquitlam and the diversion tunnel is located 7 kilometres from the west side of the Coquitlam Dam.

During outages of the tunnel, we’ll be diverting water into the Coquitlam River which passes through the cities of Coquitlam and Port Coquitlam. Please be aware of the potential for sudden fluctuations in water levels and water flows in and around the river.

Coquitlam diversion tunnel map


To do this upgrade work, we’ll need remove the tunnel from service.  Using extensive hydrological modelling to study historical weather and inflows into the reservoirs and river, we’ve determined the best approach would be to carry out the work in a series of outages.

  • Outage 1 – January 4 to April 15, 2021
  • Outage 2 – August 4 to September 30, 2021
  • Outage 3 – January 17 to May 15, 2022
  • Outage 4 – August to September 2022
  • Outage 5 – January to July 2023

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