While water continued to be piped to New Westminster and adjacent areas for drinking water, most of the flow from Coquitlam Lake was diverted out of the watershed through the tunnel to Buntzen Lake and downstream to penstocks leading to an electrical power generating plant at sea level on the Indian Arm of Burrard Inlet. The Buntzen Lake hydroelectric project was one of the first constructed in British Columbia.
Because of increasing demand for electricity due to rapid population growth, another larger dam was completed by 1915, and most of the water flowing into Coquitlam Lake was licensed in perpetuity to the power company for production of electricity. This dam raised the lake level by an additional 18.3 metres (and increased the surface area of the lake by approximately 30% to 12 km2) but did not provide access for fish passage like the previous two dams. Coquitlam Lake now has an amazing depth of > 185 (when full) and the lake bottom at this point is below sea level.
BC Hydro, the owner of the dam, completed upgrades to this earth and rock fill dam in 1985. In late 2009, a new dam was constructed immediately downstream from the existing dam to address seismic concerns. The present dam has a crest length of approximately 400 metres with base, crest and gravity spillway elevations of 133, 161.4 and 152 metres respectively. The general annual range of lake surface elevations is between 146 and 150 metres above sea level, although these ranges may vary. BC Hydro currently produces approximately 200 gigawatt hours of electricity each year – enough to provide electricity for approximately 18,000 homes.
Fish passage facilities have not been incorporated in any of the design, construction or upgrade work completed to date on the Coquitlam Dam. However, an adult fish trap to capture returning spawners as well as a new knife gate in the Low Level Outlets was added around the time of the seismic upgrade. Additionally, Coho Salmon are now being trucked into lake tributaries for spawning since 2019.
As a result of construction of the Coquitlam Dams over the last century, fish access to large areas of salmon spawning and rearing habitat above the dam was cut off, the Coquitlam Sockeye Salmon run was extirpated. Substantially reduced water flows severely impacted salmon spawning and rearing habitat below the dam, contributing to a severe decline in salmon production in the river system. Sockeye Salmon require a lake ecosystem for juvenile rearing as part of their lifecycle and the loss of access to Coquitlam Lake devastated this unique fish population and severely impacted the Kwikwetlem people. Ongoing fisheries research and recovery work through the Kwikwetlem Sockeye Restoration Program were able to determine a residual population of Kokanee Salmon, a freshwater variant of Sockeye Salmon with the same genetics, remained in the lake. These Kokanee Salmon have been thoroughly research and even used to provide brood stock for Sockeye Salmon Recovery. The first adult Sockeye Salmon returns to the Coquitlam River occurred in 2009 but unfortunately have been very minimal since that time. BC Hydro, in collaboration with KFN and GVWD are constructing a Sockeye Salmon Hatchery 1KM downstream of the dam with capacity to raise and release 30,000 juvenile fish each spring. It is hoped that this new facility to further contribute to Sockeye Salmon restoration efforts and the ultimate goal of a self-sustaining population once again on the Coquitlam River.
It is hoped that through implementation of the new Coquitlam-Buntzen Water Use Plan, increased water flow management regimes initiated by BC Hydro in 2010, in combination with the completion of new spawning and rearing habitats and continuing hatchery and stewardship operations, will improve conditions and increase salmon production in the river system downstream from the dam. Efforts are continuing toward re-establishing runs of sockeye and other salmon species in the area above the Coquitlam Dam by establishing continuity between the two watersheds, either by a trap and truck procedure, or preferably by fish ladder.
