Afon Senni

A view into the Senni Valley where the Afon Senni flows north eventually joining the Usk at Sennybridge

The Afon Senni is a river in Powys, Wales which rises in the Fforest Fawr section of the Brecon Beacons National Park and flows northwards for 11 kilometres (7 mi) to a confluence with the River Usk at Sennybridge.

The river rises as Blaen Senni to the north of the peak of Fan Nedd and east of Fan Gyhirych (51.8621°N 3.5931°W / 51.8621; -3.5931 (Afon Senni (source))), occupying a deep glacial trough until it reaches the hamlet of Heol Senni. Before reaching Sennybridge (51.9455°N 3.5723°W / 51.9455; -3.5723 (Afon Senni (mouth))), it flows past the village of Defynnog, where it is joined on its left bank by its sole significant tributary, the Nant Treweryn (or Treweren).^[1]

The river's name probably derives from a personal name 'Senni'.^[2]

The river is designated as a special area of conservation in respect of its population of three species of lamprey, twaite shad, European bullhead, Atlantic salmon and otter.^[3]

References

1. Ordnance Survey Explorer map OL12 'Brecon Beacons National Park: western area'
2. Owen, H.W. & Morgan, R. 2007 'Dictionary of the Place-names of Wales' Gomer Press, Ceredigion
3. River Usk/ Afon Wysg Archived 2010-10-13 at the Wayback Machine