Kuybyshev Reservoir on the River Volga is the largest riverine water body in Europe and is one of the most important components of the Volga-Kama cascade of reservoirs. Its dam (Volzhskaya Dam) was built near the city of Zhiguliovsk in accordance with the scheme made by the Institute of Hydroproject. The construction of this reservoir was began in October 1955 and completed in May 1957. This multi-purpose artificial water body carries out seasonal, week by and daily regulations of the flows of the Volga. Water discharged through Volzhskaya Dam flows into the Saratov Reservoir which is the next stair in the Volga-Kama cascade.

The reservoir is located in the eastern part of Russian Plain. The middle course of the Volga where the reservoir is situated was formed several million years ago in Pliocene, and was flooded by the water of Paleo-Caspian Sea during its transgression period. The reservoir is more than 400 km long, and consists of several sections or reaches, of which the largest is Cheremshan Bay with a water volume of more than 1 km³. There are many inlets near inflowing river mouths. The right (western) bank is high (up to 300 m) and steep. The submerged bed of the Volga runs near the right bank, forming a zone of maximum depth.

Major tributaries are the Rivers Viatka, Sviyagha and Bolshoy Cheremshan. Ninety-nine percent of the total inflowing water come from surface runoff, precipitation on the reservoir surface accounting for only 1%. On an average, the Volga contributes 43%, the R. Kama 38%, and the R. Viatka 11% of the total water influx. The input of the Volga water to the reservoir is controlled by six upstream dams and that of the Kama by three other dams.

The climate of the region is temperate, continental and transitional from humid to semi-arid climate. The northern part of the reservoir is in the forest zone, while its southern part belongs to the forest-steppe region. After the reservoir formation, daily mean temperature in the coastal area became lower by 1.5deg C in spring, and rose by more than 2deg C in autumn.

There are a lot of cities and towns along the shore of the reservoir. Some of them such as Kazan, Ulianovsk and Tolyatty have grown into large industrial centers of the country. Irrigated lands are widely developed in the catchment area. The growth of productivity in this region is associated with the increase of water use, which, however, negatively affects the environment and sanitary condition of the reservoir's water resources in turn (1, 2, 3, 4, 5, 6).