River Usk River Usk The River Usk (; ) 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 flows north into Usk Reservoir, then east by Sennybridge to Brecon before turning southeast to flow by Talybont-on-Usk, Crickhowell and Abergavenny after which it takes a more southerly course. Beyond the eponymous town of Usk it passes the Roman legionary fortress of Caerleon to flow through the heart of the city of Newport and into the Severn estuary at Uskmouth beyond
Pend Oreille River Fork River enters the lake from its eastern end). It flows west, receiving the Priest River from the north at the town of Priest River, then flows into southern Pend Oreille County in northeastern Washington at Newport. Once in Washington it turns north, flowing along the eastern side of the Selkirk Mountains. It flows roughly parallel to the Idaho border for approximately , through the Colville National Forest, past Tiger and Metaline Falls. It crosses the international border into southeastern British Columbia, looping west for about and joining the Columbia from the east, approximately north of the international border and