Construction started in the USSR in 1968 and mostly completed by 1986. Complex consists of power plant built in dam 548 m long, concrete spillway dam 120 m long, earth fill dams with total length of 3355 m, and a single-chamber two-lane lock. Total water front length is 4480 m. Installed power is 1404 MW, designed average annual production is 3310 GWh, but actual annual production is 2100 GWh due to lowered reservoir level. Power house has 18 generator units with Kaplan turbines, each 78 MW at 12.4 m head. The dam forms Cheboksary Reservoir with surface area of 2182 km².
Reservoir level problem
The station began to work in 1981 with normal water level lowered to 63 m above sea level. Most of flooded land belonged to Mari El Republic. Flooded land included valuable meadows, several hundred acres ( hectares ) of oak forest that was not duly felled.
Rising normal water level to design value of 68 m was hindered first by incompelete reservoir banks protection, then being opposed by Nizhny Novgorod Oblast and Mari El Republic. Now the station is operating at 63 m water level, with actual installed power of 800 MW and average annual production of 2100 GWh. Also lowered level poses difficulties to navigation on the Volga river between Nizhny Novgorod and Gorodets, with allowed drift down to 3 m, whereas it is 4 m on other parts of the Volga. Water quality in reservoir degrades because shallow waters comprise 33% af its area instead of designed 19%. The water level problem is still being discussed.
Further water level rise will cause flood of vast areas of Nizhny Novgorod Oblast and Mari El, including most part of Nizhny Novgorod between the Oka and the Volga rivers.