The Afon Llynfi is a short river in the county of

Powys Powys (; ) is a county and preserved county in Wales. It is named after the Kingdom of Powys which was a Welsh successor state, petty kingdom and principality that emerged during the Middle Ages following the end of Roman rule in Britain. Geog ...

, south

Wales Wales ( cy, Cymru ) is a country that is part of the United Kingdom. It is bordered by England to the east, the Irish Sea to the north and west, the Celtic Sea to the south west and the Bristol Channel to the south. It had a population in ...

. A tributary of the

River Wye The River Wye (; cy, Afon Gwy ) is the fourth-longest river in the UK, stretching some from its source on Plynlimon in mid Wales to the Severn estuary. For much of its length the river forms part of the border between England and Wales ...

, it runs approximately south to north just to the west of the Black Mountains and partly within the

Brecon Beacons National Park The Brecon Beacons National Park ( cy, Parc Cenedlaethol Bannau Brycheiniog) is one of three national parks in Wales, and is centred on the Brecon Beacons range of hills in southern Wales. It includes the Black Mountain ( cy, Y Mynydd Du) i ...

Geography

The river rises as a small stream to the west of the village of

Bwlch Bwlch (meaning ''a pass'' in Welsh) is a small village and an electoral ward in Powys, southern Wales. The settlement is strung out along the A40 road which crosses a low col above the Usk Valley at this point on its route between Brecon and C ...

and flows north for two miles into Llangorse Lake. It leaves the lake just to the southwest of the village of

Llangors Llangors (also known as Llangorse) is a small village, community and electoral ward in southern Powys, in the historic county of Brecknockshire, within the Brecon Beacons National Park. Description Llangors lies a few miles east of Brecon, betwe ...

and follows a course past the hamlets of Trefecca and Tredustan. The river then travels between the twin villages of

Talgarth Talgarth is a market town, community and electoral ward in southern Powys, Mid Wales, about north of Crickhowell, north-east of Brecon and south-east of Builth Wells. Notable buildings in the town include the 14th-century parish churc ...

and

Bronllys Bronllys is a village and community in Powys, Wales between the nearby towns Brecon and Talgarth. Bronllys is also the name of an electoral ward to Powys County Council. The community includes Llyswen. Description The village is in the histori ...

, forming the boundary of the national park in part. It then flows northeast past the village of Three Cocks (otherwise known as Aberllynfi) before entering the River Wye just upstream of

Glasbury Glasbury ( cy, Y Clas-ar-Wy), also known as Glasbury-on-Wye, is a village and community in Powys, Wales. The village lies at an important crossing point on the River Wye, connecting the historic counties of Brecknockshire and Radnorshire, and is ...

Bridge. The Afon Llynfi is joined by a number of tributary streams including the Tawel and Gwlithen on its left bank and the Nant Cwy (emptying directly into the lake) and Nant yr Eiddil on its right bank. The two largest tributaries are those of the Dulas which enters on the left just above Bronllys Castle Bridge and the River Ennig which enters just downstream on the opposite bank, having flowed through Talgarth. The publicly accessible falls at Pwll y Wrach on this tributary are a local attraction.

Geology

During the deglaciation of Wales there was a period when ice from the Wye Valley Glacier blocked the exit of the river into the Wye. The waters of the Llynfi backed up at Llangors to the point where they overflowed the

col In geomorphology, a col is the lowest point on a mountain ridge between two peaks.Whittow, John (1984). ''Dictionary of Physical Geography''. London: Penguin, 1984, p. 103. . It may also be called a gap. Particularly rugged and forbidding co ...

s at Pennorth and at

(both at a height of 189m) and flowed south into the

River Usk The River Usk (; cy, Afon Wysg) 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 ...

which was by this time free of ice. This situation prevailed for several hundred years as evidenced by lake deposits beneath and around Llangorse Lake.

2020 pollution incident

In 2020 a pollution incident on the Llynfi resulted in an extensive

fish kill The term fish kill, known also as fish die-off, refers to a localized die-off of fish populations which may also be associated with more generalized mortality of aquatic life.University of Florida. Gainesville, FL (2005) ''Plant Management in Fl ...

and other ecological damage.Natural Resources Wales to make decision ‘soon’ on whether to prosecute over River Llynfi pollution incident
Fergus Collins, ''www.countryfile.com'', 1 October 2020,, accessed 18 October 2022. Quote: In July (2020), several miles of the Afon Llynfi at the northern edge of the Brecon Beacons National Park was stripped of all life by a sudden and severe pollution incident.

References

{{DEFAULTSORT:Llynfi Afon Llynfi Rivers of the Brecon Beacons National Park Rivers of Powys Wye catchment

Geography

Geology

2020 pollution incident

See also

References