Hay-on-Wye the north-easternmost tip of the Brecon Beacons National Park, just north of the Black Mountains. The town is just on the Welsh side of the border with Herefordshire, England, here defined by the Dulas Brook. Where the brook joins the River Wye just north of the town, the border continues northwards along the river. The Wye was the boundary between the former counties and districts of Radnorshire and Brecknockshire. The adjacent village of Cusop lies on the English side of the Dulas Brook. The nearest city is Hereford, county town of Herefordshire, some to the east. The Royal Mail depot
Afon Llynfi (Wye) lake deposits beneath and around Llangorse Lake. Afon Llynfi (Wye) The Afon Llynfi is a short river in the county of Powys, south Wales. A tributary of the River Wye, it runs approximately south to north just to the west of the Black Mountains and partly within the Brecon Beacons National Park. The river rises as a small stream to the west of the village of Bwlch and flows north for 2 miles into Llangorse Lake. It leaves the lake just to the southwest of the village of Llangors and follows a course past the hamlets of Trefecca and Tredustan,