There are many man-made leats near Ystradfellte reservoir dam re-directing natural streams so that they flow into the reservoir. They are lined with cut stone blocks in many places and there are quite a few stone built retaining walls where their course has necessitated cutting into the hillside.
Uploaded to Geograph by James Ayres on 4 May 2014
Photo © James Ayres, 4 May 2014. Licensed for reuse under this Creative Commons licence