The Porsuk River also Kocasu-Porsuk River (Turkish: Porsuk Çayı, Kocasu-Porsuk Çayı) is a Turkish river, that flows for 448 km. The city of Eskişehir is sited on the banks of this river. The river is dammed by the Porsuk I dam and Porsuk II dam forming large reservoirs.