The Vazuza, a river in the Novoduginsky and Sychyovsky districts of Smolensk Oblast and in the Zubtsovsky District of Tver Oblast, Russia, becomes a right tributary of the Volga. It is 162 kilometres (101 mi) long, and its drainage basin covers 7,120 square kilometres (2,750 mi2). Soviet engineers flooded the lower part of the river to form the Vazuza Reservoir. The towns of Sychyovka and Zubtsov are located on the banks the Vazuza. The main tributaries of the Vazuza are the Kasnya, the Gzhat, the Losmina and the Osuga (left).