The Tersakkan River is a river of Kazakhstan. A left tributary of the Ishim River, it is 334 kilometres (208 mi) long and has an area of 19,500 square kilometres (7,500 sq mi). It flows through the western parts of Kazakhstan Uplands and the average annual flow is approximately 2.5 cubic metres per second (88 cu ft/s), with a maximum up to 52.7 cubic metres per second (1,860 cu ft/s). The river freezes in November and thaws in mid-April. Peak flow is in April during snowmelt.