River Thaw

The River Thaw (Welsh: Afon Ddawan) (also Ddaw) is a river in the Vale of Glamorgan, south Wales. At 20 kilometres/12.4 miles, it is the longest river entirely in the Vale of Glamorgan.

Course

Its source is in the hills just south of the M4 Motorway near Llanharry. It flows in a generally south-eastern direction through the town of Cowbridge, then turns southward and reaches the Bristol Channel at Breaksea Point, south of Aberthaw.

Environment

The river supports healthy populations of a variety of fish. However, several stretches of the river no longer support a single European water vole population, despite having a once sizeable population. Unlike many rivers in south Wales, the Thaw was never subject to much pollution, except at its mouth which was diverted to feed the Aberthaw Power Station. In the last century, there has been a slight decline in the river's biodiversity. Its major tributary, the Kenson River, is polluted in its lower reaches due to agricultural run-off and effluents leaking from nearby quarries. The river is also a popular site for various kinds of recreation, accessible for much of its course, much of which is used for agriculture. There are many archaeological sites along the river. The river was once large enough for the villages and settlements along its banks to have access to shipping and thus the sea. Its estuary was as wide as other Welsh rivers, but siltation and impoundments have reduced its size considerably.