The Afon Hydfer is a short river in

Powys Powys ( , ) is a Principal areas of Wales, county and Preserved counties of Wales, preserved county in Wales. It borders Gwynedd, Denbighshire, and Wrexham County Borough, Wrexham to the north; the English Ceremonial counties of England, ceremo ...

in the west of the

Brecon Beacons National Park Brecon Beacons National Park, officially named Bannau Brycheiniog National Park (), is a National parks of the United Kingdom, national park in Wales. It is named after the Brecon Beacons (), the mountain range at its centre. The national park ...

, south

Wales Wales ( ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by the Irish Sea to the north and west, England to the England–Wales border, east, the Bristol Channel to the south, and the Celtic ...

. Its headwaters rise on the northeastern slopes of the Black Mountain as the streams named Trinant, Nant y Cadno, Nant yr Erydr and Crognant, joining to flow down Cwm yr Afon on the western edge of

Glasfynydd Forest Glasfynydd Forest is an extensive area of coniferous plantations in the west of the Brecon Beacons National Park in Wales. It straddles the border between the counties of Powys and Carmarthenshire. The forest is divided into three blocks: * The ...

. The river turns east at Blaenau Uchaf, then northeast through Cwm Hydfer and joins the

River Usk The River Usk (; ) rises on the northern slopes of the Black Mountain (''y Mynydd Du''), Wales, in the westernmost part of the Brecon Beacons National Park. Initially forming the boundary between Carmarthenshire and Powys, it flows north int ...

just below Pont ar Hydfer. Other tributaries of the Hydfer include the streams of Nant Cil-y-clawdd, Nant Crinog and Nant Meity.Ordnance Survey Explorer map OL12 'Brecon Beacons National Park: western area'

References

Rivers of the Brecon Beacons National Park Rivers of Powys {{Wales-river-stub