Vasiugan

a river in Tomsk Oblast, RSFSR, the left tributary of the Ob’ River. Length, 1,082 km; basin area, 61,800 sq km. Originates in the marshes of the Vasiugan’e and flows along the Western Siberian plain. The Vasiugan is a calm, winding river. In its upper reaches it has low, swampy banks and a broad floodplain; in the middle reaches the height of the banks increases; in the lower courses there are many islands and sandbanks. It emerges in several branches. (The branch 11 km below the settlement of Kargasok is considered the mouth.) The floodplain abounds in lakes and old riverbeds. The river is fed by snow and rain. The mean annual flow rate is 381 cu m per sec (village of Naunak). The Vasiugan freezes in November and thaws in May. The largest tributaries are the Niurol’ka and Chizhapka from the right and the Chertala and Iagyl”iakha from the left. It is navigable above the inhabited point of Grabtsovy. There are deposits of petroleum and gas in the Vasiugan basin.