a river in Tiumen’ Oblast, RSFSR; left tributary of the Trom”egan River, near its junction with the Ob’ River. The Agan is sometimes considered a right tributary of the Ob’. It is 544 km long, and its basin area is 32,200 sq km. Its source is the swampy watershed which separates the Pur River basin and the right tributaries of the Ob’. It flows through the central section of the West Siberian plains. The Agan is fed primarily by snow and rain; its flowrate averages 260 cu m/sec. It freezes at the end of October, and its ice breaks in May.