page_title: Daniel-Johnson dam
section_title: Background
hierarchical_section_title: Daniel-Johnson dam / Background
caption_attribution_description: Français&#160;: Arpentage de la rivière Manicouagan: 5e saut des premières chutes English: Surveying the Manicouagan River: 5th rapids of the first falls
context_page_description: The Daniel-Johnson dam, formerly known as Manic-5, is a multiple-arch buttress dam on the Manicouagan River that creates the annular Manicouagan Reservoir. The dam is composed of 14 buttresses and 13 arches and is 214 km north of Baie-Comeau in Quebec, Canada. The dam was constructed between 1959 and 1970 for the purpose of hydroelectric power production and supplies water to the Manic-5 and Manic-5-PA power houses with a combined capacity of 2,660 MW. The dam is 214 m tall, 1,314 m long and contains 2,200,000 m³ of concrete, making it the largest dam of its type in the world.
  The dam was named after Daniel Johnson, Sr., the 20th Premier of Quebec, who was responsible for starting the project while serving as a minister in Duplessis's government. Johnson died on 26 September 1968, on the day he was to preside over the scheduled inauguration of the dam. The facility is owned and operated by Hydro-Québec.
context_section_description: During the summers of 1919 and 1920, hydrological studies were conducted on the Manicouagan and Outardes rivers, flowing into the St. Lawrence near the town of Baie-Comeau. The combined flow was then estimated at 40 million cubic meters, making it one of the largest hydrological systems in Canada. Although harnessing of this potential was considered interesting, its distance from major load centres and the lack of roads in the area were identified as major drawbacks. In addition, building dams in the wilderness was considered too costly.
  After the Second World War, the discovery of large iron deposits on the North Shore and the increased forestry activity led to a rapid development of the region. The area's largest cities, Sept-Îles and Baie-Comeau, were now linked to the rest of the province by a road. At the same time, industrial development in southern Quebec required a larger electric supply. Improvements in long distance electric transmission technologies were also a consideration at the time. Significant advances in the field, including the construction of two 315-kilovolt lines, between the Bersimis complex, west of the Manicouagan system, and Montreal, (completed in 1956), lifted another obstacle.
  In 1955, Hydro-Québec launched a 5-year extensive assessment of the Manicouagan's suitability. These studies demonstrated the exceptional potential of the river and stressed the advantages of building a multi-dam system in order take full advantage of the terrain and water flows. The data collected at the time was so promising that Hydro-Québec did not wait for the working group to submit their final recommendations. By 1959, a decision was made and construction of a 210 kilometres (130 mi) access road from Baie-Comeau was started. The original project, the Manicouagan-Outardes project, included the construction of five dams on the Manicouagan River (Manic-1, Manic-2, Manic-3, Manic-4 and Manic-5) and three on the Outardes River (Outardes-2, Outardes-3 and Outardes-4). However, a miscalculation prevented the construction of the Manic-4 dam and powerhouse because engineers realized early on that it would encroach on the Manic-3 reservoir.
  In 1959, the Premier of Quebec, Maurice Duplessis, wanted a U.S. firm to construct the dam but Quebec's Minister of Water Resources at the time, Daniel Johnson was against the idea. Johnson believed that the skill of a Canadian firm and workers was well suited for the construction of such a complex dam. Duplessis' successor in 1959, Paul Sauvé agreed with Johnson and he continued to pave the way for the dam. Eventually, engineers would choose André Coyne's design for a multiple arch buttress dam as the most suitable and economical.
caption: A hydrological survey was conducted on the Manicouagan river in 1919.
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