Llyn y Fan Fach

Llyn y Fan Fach is a glacial lake in the Brecon Beacons National Park in Carmarthenshire, Wales, sitting at an elevation of 510 meters (1673 feet). A dam extends along the northern shore below the slopes of the Black Mountain, while steep rock faces surround the water on the southern side.

Work on the dam began in 1914 to channel water to Llanelli but paused when the first workers left for military service. Conscientious objectors completed the project during World War I, creating a reservoir for the growing coastal town.

The Welsh name translates as little lake at the summit, reflecting how moorland communities once described high water sources. Local shepherds still walk paths around the shore during lambing season each spring.

A water company road leads uphill from the car park in Llanddeusant to the lake, providing access to walking routes across open moorland. Visitors should bring weatherproof clothing, as conditions at this elevation can shift quickly, especially with wind.

Water flows northward into the River Sawdde while streams on the southern side drain through Twrch Fechan and Nant Menyn into the River Tawe system. This divide means rainwater falling on either side of the lake reaches different valleys.