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 hydroelectric power production and supplies water to the Manic-5 and Manic-5-PA powerhouses 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.
At its thickest point, the center, the dam is 22.5 m wide while the crest can reach about 3 m wide. Pressure from the water behind the dam is transferred from the dam’s arches to its buttresses and lastly into the ground or its foundation.
The dam fuels two powerhouses, the Manic-5 and Manic-5-PA. The first powerhouse consists of eight Francis turbines, capable of producing up to 1,596 MW of power, which went online in 1970. The second powerhouse, the Manic-5-PA (PA stands for puissance additionnelle or additional power), was commissioned in 1989 and consists of four Francis turbines of 1,064 MW in total installed capacity.
The dam was named after Daniel Johnson Sr., the 20th Premier of Quebec, responsible for starting the project while serving as a minister in Duplessis’s government. The facility is owned and operated by Hydro-Québec.
According to the Internet