Protva

The Protva (Протва) is a river in the Moscow and Kaluga oblasts in Russia. It is a left tributary of the Oka. It is 282 km long, and has a drainage basin of 4620 km2. The area of its basin is 4620 km2. The Protva freezes up in early December and stays icebound until early April. Its main tributary is the Luzha. The towns of Vereya, Borovsk, Protvino and Obninsk are located on the shores of the Protva.