Kostroma (river)

The Kostroma () is a river in the European part of Russia. It flows through the Kostroma and Yaroslavl Oblasts, and becomes a left tributary of the Volga, which it enters at the Gorky Reservoir, at the city of Kostroma.

Prior to the flooding of the Gorky Reservoir in 1955-1957, the Kostroma River flowed into the Volga within the city limits of Kostroma. The Ipatiev Monastery stands at the old confluence of the Kostroma and the Volga.

The river is long, and its drainage basin covers . The average water flow is at the town of Buy, from the mouth, and at the mouth

Major tributaries include the Vocha, Mezenda, Vyoksa, Tyobza, and Shacha on the left, and the Shugoma, Svetitsa, Selma, Monza, and Obnora on the right.