The Afon Wysg — known in English as the River Usk — is one of Wales's most celebrated and storied rivers, rising on the northern slopes of the Black Mountain (y Mynydd Du) at the western edge of the Brecon Beacons National Park at an elevation of approximately 502 metres (1,647 feet). From its headwaters, the river drains into the Usk Reservoir before flowing eastward through Sennybridge and Brecon, then turning southeast past Talybont-on-Usk, Crickhowell, and Abergavenny, before taking a more southerly course through the town of Usk itself and ultimately joining the Severn Estuary at Uskmouth, Newport. Spanning approximately 125 kilometres (78 miles) with a catchment basin of around 1,160 square kilometres, the Afon Wysg is one of the largest rivers in south Wales. Its very name speaks to its piscatorial heritage — derived from a Common Brittonic root meaning "abounding in fish," cognate with the Welsh word pysg (fish). The river holds Special Area of Conservation (SAC) and Site of Special Scientific Interest (SSSI) status for much of its length, reflecting the extraordinary ecological richness that makes it one of the finest fishing rivers in the United Kingdom.