Bratskoye Reservoir is situated at the upper part of the Angara River. It was formed in 1961 1967 by damming the Angara River near Bratsk City.

The general planner of this reservoir and hydroelectric power plant was the Saint Petersburg Department of the Institute "Hydroproject". The cost of this project development and construction was 789.2 million rubles including 213.63 million rubles for the reservoir construction.

Bratskoye Reservoir is of the channel type with long-term storage regulation.

The water resources of this man-made lake are widely used for hydroelectric power generation, navigation and transportation, fisheries, recreation and timber-rafting.

The capacity of the Bratsk hydroelectric power station amounts for to 4.5x1.0E+6 kWh.

This reservoir operates in a cascade with the reservoirs Irkutskoye (upstream) and Ust-Ilimskoye (downstream).

The drainage basin of Bratskoye Reservoir includes the drainage basins of Lake Baikal, Irkutskoye Reservoir and its own partial drainage basin between the dams of the Irkutsk and Bratsk hydroelectric power plants. The partial drainage basin accounts for 22% of the total drainage area and consists of two parts; north-eastern plain and south-western mountains. The plain part is situated on the Siberian Plateau formed by thick sedimentary rocks of Cambrian, Ordovician and Silurian systems. The mountain part is characterized by the presence of rocks from Archean to Quaternary period with mass intrusions of gneiss, crystalline slate with seams of quartzite and marble (Q).