In the end of 1920s - the beginning of 1930s of the 20th century, the attention of scientists of Russia was attracted by a unique combination of highly effective fuel and energy, mineral, wood and other resources concentrated on the territory of the Irkutsk area. Angarsk Bureau created during this period in the structure of the State Plan of the USSR carried out complex researches and executed economic calculations, which showed advantages and prospects of creation of power-consuming industries (chemical processing of wood, chemistry, metallurgy) on the basis of hydraulic engineering resources of the Angara.
The concept on the basic directions of development of the national economy of the Angarsk Territory was approved at the first All-Union Conference on development of productive forces of the country, which was held in 1932, where the key part was assigned to fuel and energy resources, and, first of all, water-power engineering.
The long-term concept of the Angarsk project was considered and accepted at the second All-Union Conference on studying of industrial forces, which took place in 1947 in Irkutsk.
The 5-th five-year period (1951-1955) of the national economy development singled out construction of the hydroelectric power station on the Angara as a priority action.
Within the limits of development of the concept of the Angarsk project, in 1959 the Moscow State Institute of Power Stations and Substations Designing founded Angarsk Comprehensive Exploratory Party in Nevon settlement for studying thermal mode of the Angara and direction of laying of the future high-voltage lines. In September of 1960, the State Commission made a decision to declare that the most convenient place for erection of Ust-Ilimsk hydro-unit is the site located 20 km below the mouth of the IIlim River, on the Angara, at the rocky Tolsty Cape.
Gidroproekt All-Union Design and Exploratory Institute named after S.Y. Zhuk performed works on development of the contract design for construction of Ust-Ilimsk Hydroelectric Power Station.
The following was determined by the decision of the Central Committee of the CPSU and Ministerial Council of the USSR as of June 8, 1962:
Beginning of construction - 1963
Installed capacity: I stage - 15 units; full - 18 units; actual - 16 units (3840 MW)
Stages of construction
I stage: 1963-1967. The building site was prepared; concrete, reinforcing plants, settlement, Bratsk-Ust-Ilimsk 220 kV high-voltage lines were constructed
June, 1966 - through traffic on Bratsk-Ust-Ilimsk motorway was opened
March 1966 - the beginning of works on the basic constructions of hydro-unit
February 1967 - the first damming on the Angara River
April 22, 1968 - 1-st cubic meter of concrete in the dam of the hydroelectric power station is laid.
August 13, 1969 - the second damming of the Angara
October 3, 1974 - filling of Ust-Ilimsk water basin