Visit Manic‑5 generating station and Daniel‑Johnson dam!

Daniel Johnson, Sr., then‑Minister of Hydraulic Resources, launched the project to develop the Manicouagan and aux Outardes rivers. This was the prelude to a great adventure: The government-owned corporation performed a series of technical feats to tame these northern rivers and transmit high volumes of energy over several hundred kilometres to supply major consumer markets in the Québec and Montréal metropolitan areas.

The Manic‑5 hydropower development’s construction site quickly became the largest in North America. Work on the huge dam with 13 arches and 14 buttresses only progressed six months a year, during the warmer months, because pouring concrete requires temperatures between 7 to 15°C. To make up for the time lost in winter, the jobsite operated 7 days a week, 24 hours a day, thanks to a permanent lighting system. More than 12,900 employees worked to build the facility. At the height of the work in 1964, there were 3,500 people working there.

The reservoir took many years to fill! It covers an area of approximately 2,000 km², twice that of Lac Saint‑Jean, and is 200 km long, the same as the distance between Baie‑Comeau and Manic‑5 generating station. At the foot of the dam’s main arch, openings let the water pass through the dam to discharge it downstream. They made it possible to regulate the reservoir’s water level to prevent it from rising higher than the structure under construction. A certain flow of water was needed to supply Manic‑2 generating station’s first generating units, commissioned in 1965. With this ingenious system, Hydro‑Québec was able to build the dam and fill the reservoir at the same time.

The magnitude of the work at Manic‑5 was such that it made people tremendously curious. To satisfy their curiosity, the decision was made to broadcast the construction live during Expo 67 in an exhibition hall in the Québec Industries pavilion. The general public was thus able to see the progression of the work and the workers on the construction site.

The inauguration of Manicouagan‑5 dam was scheduled to take place on September 26, 1968, but the day before the event, Daniel Johnson, Premier of Québec, died of a heart attack on the site of Manic‑5. The ceremony was postponed for a year to the day, to September 26, 1969. The dam is now named Daniel‑Johnson dam to commemorate the man who had launched its construction 10 years earlier, in 1959.

Manic‑5 generating station was commissioned and began supplying the Québec population with energy. However, this didn’t mark the end of construction at the Manic‑Outardes complex. The last of its construction sites closed in 1978. It took almost 20 years to build the complex’s many facilities, and thousands of people worked on the project.

Another particularity of Manic‑5 is that a second generating station, an underground one, was built there: Manic‑5‑PA. “PA” stands for puissance additionnelle (additional capacity), in reference to the fact that the generating station was originally built to meet the increased demand for electricity during winter peak periods.

When it was commissioned, Manic‑5‑PA generating station had four generating units and an installed capacity of 1,064 MW.