Llyn Brianne
General data
- Name: Llyn Brianne
- Water system: River Towy
- Water type: Artificial lake
- Progression: River Towy -> Bristol Channel -> Celtic Sea -> Atlantic Ocean -> Planet Earth
- Climates: Temperate
- Continents: Europe
- Countries: Wales (UK)
Llyn Brianne is a man-made reservoir in the headwaters of the River Towy in Wales. It was constructed by Wimpey Construction in the late 1960s and early 1970s in order to regulate the flow in the Towy to support large potable water abstraction at Nantgaredig in the lower reaches of the river near Carmarthen; providing water to the Felindre water treatment works. The treated water is piped to a large area of South Wales which includes Swansea and Neath and the western periphery of Cardiff.