The River Elwy (Afon Elwy in Welsh) is a river in Wales and is a tributary of the River Clwyd. The source of the river is sometimes said to be on the northern flank of Moel Seisiog, south-east of Llanrwst, at Ordnance Survey grid reference SH853593. However the river is only actually called the Elwy at the village of Llangernyw, where three rivers, Afon Cledwen, Afon Collen and Afon Gallen, meet to form the Elwy.