Afon Llynfi (Wye)

The Afon Llyfni near Three Cocks

Not to be confused with the River Llynfi in Glamorgan nor the Afon Llyfni in Caernarfonshire

The Afon Llynfi is a short river in Brecknockshire, running from Llangorse Lake, below the Black Mountains, northwards to joint the River Wye. It is partly within the Brecon Beacons National Park.

Course

The river rises as a small stream to the west of the village of Bwlch and flows north for two miles into Llangorse Lake. It leaves the lake just to the south-west of the village of Llangors and follows a course past the hamlets of Trefecca and Tredustan. The river then flows between the twin villages of Talgarth and Bronllys, forming the boundary of the Brecon Beacons National Park in part. It then flows north-east past Three Cocks (also known as Aberllynfi after the river) before entering the River Wye just upstream of Glasbury Bridge.

The 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 falls at Pwll y Wrach on this tributary are a local attraction, and publicly accessible.

Geology

At the end of the last Ice Age, 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 cols at Pennorth and at Bwlch (both at a height of 620 feet above sea level) and flowed south into the River Usk 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.

Location

• Location map: 52°1’53"N, 3°13’5"W
• Streetmap: SO165376

See also

• Pwll y wrach, the "Pool of the Witch" near Talgarth.