When the Soviets invaded Afghanistan in 1979, the contractors left. They had intended to raise the dam by 2 meters in order to increase the available water for power production and irrigation. They were also excavating an emergency spillway which was never completed. Gates were also never installed in the service spillway so the dam passes all water in the reservoir above elevation 1033.5 meters. Completion of the spillway gates would increase the total storage capacity of the reservoir by to .