River Clydach, Brecknockshire
The River Clydach is a short, steep and fast-flowing river in Brecknockshire. It lies within the Brecon Beacons National Park. It is around six miles in length.
The river rises on the southern slopes of Llangattock Mountain (51°48’44"N, 3°11’38"W) then heads south-east through Clydach Dingle past Brynmawr. It then enters the spectacular Clydach Gorge, dropping about 1,000 ft to Gilwern and its confluence with the River Usk (51°49’58"N, 3°6’3"W).[1]
"Clydach" is a common name for watercourses in south Wales and is thought to derive from an old Welsh language word for "swift" or possibly "stoney", both of which would apply in this case.[2]