Ystradfellte Reservoir is a water storage reservoir on the Afon Dringarth in the upland area of Fforest Fawr within the Brecon Beacons National Park in South Wales. It lies just north of the village of Ystradfellte in the county of Powys at OS Grid ref SN 946178. The embankment is 920 feet (280 m) long by 114 feet (35 m) high. When full the water surface is 1,204 feet (367 m) above sea level.