The River Usk, or Afon Wysg in Welsh - is 100km or around 62 miles, rises on the slopes of the Black Mountain, in the Brecon Beacons, weaves it's way through Abergavenny before joining the Bristol Channel at Newport. But all is not well....agricultural pollution, sewage leaks, climate change - they're all adding up to loss of habitat for wildlife and depleted fish stocks on this iconic river and what's happening in this catchment, campaigners say, is reflected on waterways across Wales. Steffan Messenger travels along the banks of the river Usk to explore the issues, beginning his journey with Guy Mawle, the author of a report "A Dying River: The State of the River Usk" and continues on to find out what needs to be done to prevent further decline and restore it.