Not to be confused with the entirely separate Lower Clydach River which is also a right-bank tributary of the River Tawe nor with the River Clydach (Neath), which is a right bank tributary of the River Neath nor the River Clydach which flows down the Clydach Gorge on the Monmouthshire/Blaenau Gwent boundary.

The Upper Clydach River runs from a poorly drained area south of Cwmgors and flows south and southeast through Cwm Gors for about 7 km to join the River Tawe at Pontardawe - .