Osetr

a river in Tula and Moscow Oblasts, RSFSR, forming part of the border with Riazan’ Oblast; a right tributary of the Oka. It is 228 km long and drains an area of 3,480 sq km. It originates in the Central Russian Upland. It is fed mainly by snow. The mean flow rate 42 km from the river’s mouth is 13.3 cu m per sec. The river freezes over in November and thaws in the first half of April. The city of Zaraisk is situated on the Osetr.