The three dams were designed to be part of a power-generating package that reuses water for each dam downstream.
Site A, the first in the series, became the W.A.C. Bennett Dam, which was built in 1967, 19 kilometres west of Hudson's Hope.
When it was completed, the dam was the largest earth-filled structure ever built, creating the Williston Lake reservoir, the largest lake in British Columbia.
Construction of the dam and reservoir sparked significant controversy because it flooded 350,000 acres of forested-land, causing loss of biodiversity and timber and mineral rights.
It also resulted in the removal of a number of residents, including the Sekani First Nation, whose displacement BC Hydro admitted in 1977, led to social isolation and had a significant impact on Sekani culture.
In 1980, the Peace Canyon Dam or Site B was built 23 kilometres downstream from the W.A.C. Bennett Dam.
Fifty metres tall and 534 metres long, the dam re-uses water already used to generate electricity from the WAC Bennett Dam.
Site C, third in the series
Early plans developed in the 1950s called for the third dam, Site C to be built 83 kilometres downstream from the Peace Canyon Dam, about seven kilometres southwest of Fort St. John, but it was never built.
The provincial government rejected the Site C dam proposal in 1982 and again in 1989 following B.C. Utilities Commission hearings, deciding it didn't need the extra electricity.
Plans for the fourth dam in the series, Site E, to be built near the B.C.- Alberta border were shelved during the 1982 hearing.
However, for the last 10 years, BC Hydro has been sounding the alarm about the growing demand for electricity.
In April 2010, the B.C. government under then premier Gordon Campbell, resurrected the Site C proposal and moved it to the regulatory review phase.
BC Hydro says the dam will provide approximately 900 megawatts of power, generating about 4,600 gigawatt hours of electricity each year — enough electricity to power more than 400,000 homes.
Because it is the third project in a one-river system, Hydro says Site C will gain significant efficiencies as it will use water already stored in the WAC Bennett Dam's Williston Lake Reservoir.
Hydro claims Site C will generate about 30 per cent of the energy produced at the W.A.C Bennett Dam, with only five per cent of the reservoir area.
The original announcement called for the site to be operational for domestic energy production by 2020 but it is already behind that schedule by a number of years.
Once construction starts, it's estimated the dam will take about eight years to build and cost about $8.5 billion.
Opposition to Site C
B.C. Hydro forecasts it will need additional sources of electricity by 2028. It purposely calls the dam, the "Site C Clean Energy Project" and claiming it will produce fewer greenhouse gas emissions for the amount of energy supplied than any other source except nuclear power.
The dam reservoir would require the flooding of approximately 5,500 hectares of land and more than 83 kilometres of river valley along the Peace River and its tributaries.
This would include over 3,000 hectares of wildlife habitats, heritage sites, and Class 1 and Class 2 agricultural land.
Members of the Treaty 8 First Nations boycotted the official announcement ceremony at the Bennett Dam in April 2010 and have launched a lawsuit opposed the dam. The First Nations say the destruction of the valley and the obliteration of a number of sacred sites would have a devastating impact.
Local farmers are also opposed to the loss of land for agriculture and environmentalists opposed the loss of wildlife habitat.
Click here for BC Hydro animation of Site C construction