The Jordan River Diversion Dam, known locally simply as Diversion Dam, is a dam on the Jordan River in Jordan River, British Columbia, Canada. Part of a multi-dam hydroelectric system operated by BC Hydro, the facility provides approximately 35% of Vancouver Island's generating capacity. It was the second hydroelectric development on Vancouver Island, succeeding the Goldstream Powerhouse.
Prior to the dam's construction, the Goldstream Powerhouse was the main source of electricity to Victoria. The Jordan River facility dwarfed the previous plant upon its completion.
The Vancouver Island Power Company, a subsidiary of the British Columbia Electric Railway, completed construction of both the smaller Bear Creek Dam and the main Jordan River Diversion Dam in 1911. At from top to bottom, the Diversion Dam was, upon completion, the highest dam in Canada. Water flowed through a long flume to a penstock above the power house.
The dam's remote location required the construction of a narrow gauge railway and a cable-railway for the initial ascent from the Jordan River valley. From 1912 to 1931, continual improvements and additional generators increased the capacity of the power house to 26 megawatts.
In 1971, the original flume was replaced by a tunnel, with a penstock feeding a new power house situated across the river from the original. The accompanying service railway was dismantled the same year. A single high-head Francis turbine and generator manufactured by Fuji Electric of Japan replaced the earlier equipment, increasing power output from 26 megawatts to 175âÂÂ183 megawatts.
The Jordan River hydroelectric system comprises several interconnected components. Water collected at Bear Creek Dam and the Diversion Dam feeds the Jordan River Diversion Reservoir, the largest impoundment in the system, with a surface area of approximately and a licensed full supply storage of about , roughly equivalent to 3.5 days of generation capacity.
From there, the Jack Elliott equalization reservoir (a much smaller headpond of about at full pool, holding only a few hours of storage) regulates flow into an long tunnel. Water then drops through a steel penstock over the final of vertical height before reaching the turbine at the generating station near the river mouth.
A 2014 BC Hydro study concluded that the Jordan River dam faced the highest seismic hazard in BC Hydro's system. A magnitude 8âÂÂ9 Cascadia subduction zone earthquake could potentially cause the dam to collapse, sending a flood wave downstream into the small Jordan River village on the coastal plain.
BC Hydro identified 11 homes within the evacuation zone that would likely be destroyed in a worst-case dam failure scenario. The utility offered to purchase all at-risk properties and ultimately negotiated buyouts for all but one. Nearly all waterfront properties below the dam were cleared, while the remainder of the village, located outside the predicted flood zone, was deemed safe.
The Jordan River system lies on the unceded traditional territory of the Pacheedaht First Nation (diitiida). In June 2018, BC Hydro and the Pacheedaht agreed to transfer approximately of the Jordan River "origin site" back to the Nation. The land transfer followed the 2014 seismic review and associated property buyouts, and was described as a historic repatriation of traditional lands. There is no public record of a specific land claim or impact-benefit agreement tied solely to the dam beyond this voluntary land transfer. The Pacheedaht continue to negotiate a broader treaty with the governments of Canada and British Columbia.
Historically, the Jordan River supported runs of several anadromous salmonid species, including pink, chum, and coho salmon, as well as steelhead (anadromous rainbow trout) and sea-run coastal cutthroat trout. Prior to mid-twentieth-century development, thousands of chum and pink salmon spawned in the river.
In 1996, the provincial government initiated a Water Use Planning (WUP) program, requiring British Columbia's water licence holders to demonstrate their ability to manage the potential environmental impact of reservoirs. The Jordan River WUP, begun in 2001, identified the legacy Sunro copper mine in the lower watershed as the chief barrier to salmon recovery. The plan specified that remediation of the mine site, including cleanup of tailings and toxic residues, should be pursued to improve fish habitat, and that completion of such remediation should trigger a review of the WUP. Other measures included maintaining minimum flows below Elliott Dam for resident trout and creating a wetland in the Diversion Reservoir drawdown zone to replace lost habitat.