The Severn Tributary is a river system in the United Kingdom that consists of three rivers: the AVON, the Usk, and the Wye. The AVON is a river in the south of England that rises in Northamptonshire and flows through Wiltshire, Somerset, and Bristol before emptying into the Severn Estuary. The Usk is a river in Wales that rises in the Brecon Beacons and flows through Monmouthshire before joining the Severn Estuary. The Wye is a river in Wales and England that rises in Powys and flows through Herefordshire before joining the Severn Estuary. All three rivers are important tributaries of the Severn River.