The reservoir was built in 1958 in order to provide drinking water to increasing population of Baku and Sumgayit. The overall area is 13.9 km2 (5.4 sq mi), volume of reservoir is 186 million m3, 150 million m3 is utilized. Length of the reservoir is 8.74 km (5.43 mi), maximum width is 2.15 km (1.34 mi), the shoreline length is 23.3 km (14.5 mi). The maximum depth of water in the reservoir is 28.5 m (94 ft) with the lowest depth registered at 14.5 m (48 ft). The water surface area is 1,389 ha (13.89 km2). The reservoir gets the water from Samur-Absheron channel which is fed by three inflowing rivers Samurçay, Vəlvələçay and Qudiyalçay. Due to containment of drinking water, a sanitary protection zone was founded around the reservoir in 1960. In 2001, the first sanitary zone was expanded and fenced off for protection of the reservoir lake. The project also included foresting and cleaning of water channels in order to improve the ecology of the lake. The fence is 23 km (14 mi) long. The reservoir also has two sets of big water pumping stations.