Pasarel Reservoir, reservoir in Bulgaria

Pasarel Reservoir is a water storage basin in Bulgaria near the village of Dolni Pasarel, roughly 20 kilometers southeast of Sofia in a valley at about 700 meters in elevation. Water flows into it from an upstream hydroelectric plant through underground tunnels and exits through pipes leading to another power station, creating a linked system for electricity generation and water management.

The Pasarel Reservoir was built as part of a hydroelectric project to store water and generate electricity, a strategy for the region to manage river flow. Its construction was part of a larger effort to use the Iskar system efficiently by capturing tailwater from power plants and serving multiple purposes in a single valley.

The reservoir takes its name from the village of Dolni Pasarel, and the smaller reservoir downstream is sometimes called Kokalyane after the next power station. Above the shore lies the Strazharski Dol area, where fighter pilot Dimitar Spisarevski was killed; the Pasarel chapel of St. George the Victorious was built in his memory. The St. Peter and Pavel monastery stands in Dolni Pasarel.

The reservoir lies 28 km southeast of Sofia's centre at 700 m altitude, in the Pancharevo Gorge between Lozen Mountain and Plana. Swimming and fishing are forbidden because the lake is a drinking-water zone. The 2010 Lozen Mountain eco-trail starts from the reservoir area and continues to Polovrak Peak, Lozen Monastery and Lozen village.

The reservoir is also known as Kokalyane Reservoir because it serves as the upper equalizer for the Kokalyane hydroelectric plant downstream, while acting as the lower equalizer for the Pasarel plant. Its concrete gravity dam is 27 m high and 94 m long along the crest, with a spillway and outlet of 800 m³/s capacity. The reservoir is a protected water-supply zone, so fishing and swimming are prohibited.