[2][4] 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.

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.

Improvements in long-distance electric transmission technologies became significant, with construction of two 315-kilovolt lines, between the Bersimis complex, west of the Manicouagan system, and Montreal, (completed in 1956) lifting another obstacle.

[6] Eventually, engineers would choose André Coyne's design for a multiple arch buttress dam as the most suitable and economical.

Each cofferdam was built on alluvial deposits (loose soil), so they needed to be watertight, which was accomplished with either a grout curtain or deep supporting piles.

Once drained, workers excavated the alluvial deposits between the cofferdams, creating a long pit that was 150 ft (46 m) deep at the centre.

Hundreds of dignitaries, politicians, utility executives, financiers, engineers and journalists were ferried by plane from Montreal, Quebec City and New York to the work-site to attend a banquet and a plaque unveiling ceremony.

Among the guests were Quebec Union Nationale Premier, Daniel Johnson Sr., his predecessor, Jean Lesage, and René Lévesque, the former Hydraulic Resources minister responsible for the consolidation of all investor-owned utilities into Hydro-Québec.

[15] In his authorized biography, Hydro-Québec executive Robert A. Boyd recalls being woken up at 6 a.m. the next morning by his boss, Roland Giroux.

To further help the structure cope with the climate, engineers placed one-inch steel reinforcing bars within the upstream and downstream faces of the dam.

[22] The reservoir is a well known area for Atlantic salmon, lake trout and northern pike fishing, although tall trees flooded during the impoundment have not decomposed due to a lack of oxygen, which can sometimes interfere with the sport.

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 power house is about 2,500 ft (760 m) downstream of the dam and utilizes two surge tanks for sudden rises in water pressure from the two penstocks.

[28] The construction of the Daniel-Johnson Dam and the Manic-Outardes complex happened in a larger social and political context of the Quiet Revolution in Quebec, a time when recently nationalized "Hydro-Québec rapidly becomes a symbol of the new Quebec nationalism and of the new economic strategy of the State", explains historian Paul-André Linteau.

In a series of papers published in Montreal's La Presse, Renaude Lapointe calls Hydro-Québec a "colossus on the march".

For instance, chansonnier Georges Dor penned his 1966 hit song, La Manic, which tells the story of a construction worker at the remote jobsite who describes his loneliness to his wife in words that captured the collective imagination of the Quebec public.

Terreur à la Manicouagan[32] is about an attempt by arch-villain Roman Orgonetz to breach the dam by destroying the surge chamber by remote-controlled detonation, a plan foiled by Morane and his Scottish sidekick, Bill Ballantine.

[33] Other notable visitors to the construction site included cartoonist Hergé, who left an original drawing of his characters Tintin the reporter and his dog Snowy posing in front of a ligne claire depiction of the dam.

A colourized version of the autographed drawing is featured at the Jean-Lesage generating station visitor's centre, 23 kilometres (14 mi) north of Baie-Comeau.

In March 2000, the Canada Post Corporation issued a 46 cent stamp featuring the Dam as part of a 4-stamp Millennium Collection sheet depicting "engineering and technological marvels".

[36] The two-hour tour includes a briefing on the construction and operation of the facility, a visit of the Manic-5 powerhouse and a bus ride to the base and the crest of the dam, which has a view of the Manicouagan River valley.