The reservoir is situated in part of the Brecon Beacons National Park. It is situated to the western end of the park, sitting below the Black Mountain (range), and most of the summits in the range are visible from the reservoir, especially (from left to right in the image) Fan Hir, Fan Brycheiniog, Fan Foel, Picws Du and Waun Lefrith. It lies about six miles to the north of the centre of the escarpment at Fan Foel, and is an important landmark for walkers on the mountain range.