The BC Power Commission completed the original John Hart Generating Station in 1947, naming it after John Hart, Premier of British Columbia from 1941 to 1947. The facility was a product of postwar optimism and Vancouver Island's growing appetite for electricity. Six turbine-generator units powered by above-ground wood stave penstocks delivered a total capacity of 126 megawatts, drawing water from the outflow of John Hart Lake on the Campbell River. It was one of three dams that would eventually tame the river -- joined later by Strathcona Dam and Ladore Dam upstream -- transforming a wild salmon river into a managed power corridor.

By 1979, BC Hydro had grown concerned about the safety of its older dams. Earthquakes had demonstrated that certain soil conditions could turn stable ground into something resembling quicksand during a tremor. A formal review, begun in 1984, confirmed the worst: John Hart Dam rested on exactly the type of loose, water-saturated sediment most susceptible to liquefaction. Rather than drain the reservoir and rebuild -- an option that would have cut power to thousands -- engineers chose a more delicate approach. They reinforced the dam by injecting grout into the foundation while the reservoir remained at full pool, threading the needle between structural necessity and continuous power generation. It was a temporary fix for a problem that would ultimately demand a more permanent solution.

In 2014, BC Hydro committed to a comprehensive replacement. Contracts went to SNC-Lavalin to design and build a new generating station, along with two new penstocks stretching two kilometres from the dam to the powerhouse. The critical difference from the original: the new penstocks and powerhouse would be built entirely underground, shielded from seismic risk and protected from the surface vulnerabilities that had plagued the 1947 facility. The project required decommissioning the old generating station in stages while simultaneously constructing and commissioning the new one -- a feat of engineering choreography that kept electricity flowing to the grid throughout the transition.

The project was completed in 2018 at a cost of 1.1 billion dollars, making it one of the largest hydroelectric projects in British Columbia in decades. The new powerhouse delivered a slightly increased capacity of 132.2 megawatts -- a modest gain in raw power, but a transformative improvement in safety, efficiency, and longevity. The underground facility was designed to withstand the seismic forces that its predecessor had been built in ignorance of. Above ground, the dam itself still holds back John Hart Lake, and the Campbell River still flows through Elk Falls Provincial Park downstream, its volume controlled by the same infrastructure that has shaped this valley since the postwar years.