Usk

The River Usk ( ; Welsh: Afon Wysg) is a river in south Wales that rises on the northern slopes of the Black Mountain range, in the western part of the Brecon Beacons National Park, and flows into the Severn Estuary at Uskmouth after flowing through Brecon, Crickhowell, Abergavenny, Usk, Caerleon, and Newport.
The river is 125 kilometres (78 miles) long and drains a basin of 1,160 km2 (450 sq mi). The Encyclopaedia of Wales, which gives its length as 137 km (85 mi), describes it as the longest river flowing wholly within Wales. Its name derives from a Common Brittonic word meaning "abounding in fish", or possibly "water".
It is designated a Site of Special Scientific Interest. Its habitats include woodland, grassland, marshes, mudflats and salt marshes. The river supports Atlantic salmon, brown trout, European otters, twait shad, and lampreys. The Usk has long been noted as a salmon and trout fishing river.
The Usk valley has been an important route for settlement and trade since prehistoric times, while the river's navigable tidal reaches connected inland south-east Wales with the Severn Estuary and the Bristol Channel. The Usk is crossed by numerous historic bridges, including several listed ones and the Newport Transporter Bridge. The river features in medieval Welsh and Arthurian literature, including the works of Geoffrey of Monmouth.

Source: Wikipedia https://en.wikipedia.org/wiki/River_Usk