Beacons Reservoir is the northernmost of the three reservoirs in the Taff Fawr valley in South Wales. It is owned by Welsh Water. As its name suggests, it is located in the Brecon Beacons National Park in the Powys unitary authority area and within the historic county boundaries of Breconshire. There is access to the Taff Trail and the Navvies Line from the car park below the dam.