The River Thaw Habitat Enhancement Project

The European Eel Anguilla Anguilla remains as critically endangered on the IUCN Red list due to a suit of threats including barriers to migration, climate change, disease, exploitation, habitat loss, pollutants and predation. Many rivers in Wales are essential to the life cycle of the eel providing a home to grow, mature and eventually return to the ocean to spawn.  One such river is the Thaw (Afon Ddawan) which flows for 20 kilometres from the source near Llanharry, through the Vale of Glamorgan and out to the Bristol Channel at Breaksea Point, south of Aberthaw.

However, parts of the River Thaw catchment are currently failing to meet the required water quality standards as laid out in the European Water Framework Directive (WFD). There is a requirement to get all water bodies in the UK to Good status to avoid financial penalties. The River is currently ranked as Moderate (borderline Good) status due excessive levels of sediment and nutrients entering the system.  This is attributed to a number of different factors including agricultural pollution and livestock poaching. Much of the River has also been straightened and dredged making parts very deep and fast flowing.   As a consequence of this, sections of the river contain very little aquatic plants and therefore poor cover for fish. Furthermore, the deep layers of mud on these dredged reaches present a reduced habitat for invertebrates, leading to a low diversity of their populations.

With support and funding from Aberthaw Power Station, Dŵr Cymru Welsh Water and Natural Resources Wales and the combined efforts from South East Wales Rivers Trust (SEWRT), Afonydd Cymru and The Wye & Usk Foundation, SEWRT has launched a habitat improvement project on the River Thaw.  The project includes working with landowners to reduce agricultural pressures such as livestock poaching via grant aided riparian fencing and provision of alternative stock drinking water. Each visit includes one to one free advice around manure and nutrient management and land practices to reduce the effects of agricultural pollution as well as financial savings to the farm business.   The project is also tasked with the enhancement of fish habitat and removal of barriers to migration.

The Project began at the end of 2017 with almost 1.5km of fencing on a section of the Thaw and the Nant Treguff at Treguff.  The Nant Treguff is a small tributary of the Thaw with the potential to be an excellent spawning stream.  Further work at this site will commence later this year to improve fish cover and access.

The River Thaw Improvement Project-1