Cheboksary Reservoir is an artificial lake in the central part of the Volga River formed by the Cheboksary Dam in Novocheboksarsk.
The surface area of Cheboksary Reservoir is , max width is , max depth is . The reservoir has partly flooded the Mari Depression.
The largest cities on the Reservoir are Nizhny Novgorod, Cheboksary and Kozmodemyansk.