Site Record

Llyn Arenig Fawr was adapted as a reservoir (nprn 511406) in 1830. The dam was altered in 1864, and the pipeline laid in 1879 and was probably modified in C20, as the prsent form of the dam is slightly different than what is shown on the 1888 OS map. A single, square-section stone pillar, located in the water close to the NE end of the dam, may relate to a pier marked on the 1888 map.
The broad dam of rubble stone, approx. 80m long, with battered face. The masonry is much repointed. In 2 sections, either side of a grass-covered projecting outcrop. The SW section is longer and has a stone-paved outflow channel.
Recorded as part of Uplands Initiative Survey. W B Horton, H&H, 14/07/2010.