The Sôr Brook is a right bank tributary of the

River Usk The River Usk (; cy, Afon Wysg) 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 flo ...

running largely in Monmouthshire in south

Wales Wales ( cy, Cymru ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, the Celtic Sea to the south west and the ...

, though the watercourse forms the boundary with neighbouring

Torfaen Torfaen (; cy, Torfaen ) is a county borough in the south-east of Wales. Torfaen is bordered by the county of Monmouthshire to the east, the city of Newport to the south, and the county boroughs of Caerphilly and Blaenau Gwent to the south- ...

in places. Its uppermost reaches were inundated by the construction of

Llandegfedd Reservoir Llandegfedd Reservoir (also known as ''Llandegveth Reservoir'') is a large 174 hectare water supply reservoir and is eight miles (13 km) north of Newport in south Wales. The reservoir is very close to Pontypool, Cwmbran and Usk, with t ...

which opened in May 1965 It now flows from beneath the dam of the reservoir southwards past Llandegveth to join the Usk in its tidal reach 1 km northeast of

Caerleon Caerleon (; cy, Caerllion) is a town and community in Newport, Wales. Situated on the River Usk, it lies northeast of Newport city centre, and southeast of Cwmbran. Caerleon is of archaeological importance, being the site of a notable Rom ...

References

Rivers of Torfaen Rivers of Monmouthshire {{Wales-river-stub