Iskar Lake (known as Pasarel until December 21, 1949, and Gigant Stalin Lake until January 19, 1962) holds the title of the largest reservoir in Bulgaria, both in volume and area. It is state-owned and maintained by the National Electric Company.
Early Beginnings
The need for a dam on the Iskar River was identified as early as 1900-1901, right after the construction of the Pancharevo Hydroelectric Power Plant. The issue resurfaced in 1921, driven by the growing water demands of the capital. A project for a 55-meter dam and a reservoir with a volume of 320 million m³ was proposed but couldn’t be realized due to the municipality’s inability to compensate the residents of Gorni Pasarel, Kalkovo, and Shishmanovo villages.
Initial Attempts
From 1932 to 1941, topographic surveys, geological assessments for the dam, and water quantity observations of the Iskar near Pasarel were conducted. These were aimed at building the “St. Peter” Reservoir (named after the monastery in Dolni Pasarel, near which the dam was to be located). The proposed dam site coincided with the present Iskar Lake dam, but it was planned to be only 46 meters high, with a reservoir volume of 200 million m³.
Renewed Efforts
In July 1947, new geological surveys commenced at four locations between Gorni Pasarel and Pancharevo to determine the best site for a dam. The site around the 37th km proved most favorable in geological, topographical, and hydrological terms. Additional studies of the Iskar River waters were carried out in 1947-1948.
The Grand Plan
Early in 1948, work began on the designs for the second level of the Iskar cascade within the newly established EnergoHydroProject. Former Sofia mayor Ivan Ivanov, initially sentenced to death by the People’s Court, was spared in exchange for designing the Iskar Reservoir. He worked under police supervision before being fully pardoned. On January 26, 1949, the project was approved by an expert council of the then Ministry of Electrification and Melioration. The reservoir was planned to have a working volume of 520 million m³ and a reserve volume of 60 million m³.
Construction and Completion
Preparatory work began in 1949, with major construction starting at the end of 1950. On September 6, 1954, the hydro complex was officially inaugurated. For its time, it was the largest technical facility in Bulgaria. On December 21, 1949, while still under construction, it was renamed “Gigant Stalin Reservoir,” a name later reverted. In 1959, the territory around the reservoir, traditionally part of Samokov, was administratively transferred to Sofia City.
Record Volumes
The reservoir reached its maximum volume of 675.5 million m³ in 1976, during a flood prevention operation when the spillway was temporarily closed and elevated. The lowest volume post-impoundment was recorded in April 1994, when, despite earlier water supply restrictions in Sofia, only 53.9 million m³ remained in the reservoir.
The Iskar Reservoir stands as a monumental achievement in Bulgaria’s history, showcasing the nation’s ability to overcome significant challenges and meet the growing demands of its capital.
