The Tolors Reservoir is located in Syunik province, about 3 km south of the town of Sisian, at the confluence of the Sisian and Ayri rivers. It is an artificial reservoir that is part of the Vorotan hydropower system. The reservoir was put into operation in 1974.
The surface area of the Tolors Reservoir is about 4.7 km², and its length is about 4.5 km. Its total capacity is about 96 million m³, of which about 80 million m³ is the active, usable volume. The maximum water depth reaches 56.5 meters.
The reservoir is formed not only from the flow of the Vorotan river but also from the flows of the Sisian and Ayri rivers. The reservoir's minimum water level is set at the mark of 1,625.5 m, since below that water level it is not possible to operate the Shamb hydroelectric power station.
The Tolors Reservoir plays an important role in the operation of the Shamb and Tatev hydroelectric power stations. Water is transferred from Tolors to the Shamb HPP through a dedicated water-conveyance system.
The Tolors dam has a rock-fill structure with a core. In dams of this type, stones of various sizes are used, whose compaction contributes to the structure's stability and reduces settling of the dam body.
Part of the territory of the old village of Tolors has remained under water, and at certain times of the year the Surb Hripsime church is visible within the reservoir. The water level of the Tolors Reservoir changes considerably over the course of the year, so whether the church can be seen depends on the season.
