Lluest-wen Reservoir

Lluest-wen Reservoir (Welsh: Cronfa-ddwr Lluest-wen) is a reservoir at the top of the Rhondda Fach Valley (Welsh: Cwm Rhondda Fach), in the borough of Rhondda Cynon Taf. Parts of it fall within the communities of Rhigos, Aberdare and Treherbert. A recreational walking route, the Coed Morgannwg Way, and route 47 of the National Cycle Network run northeast and southwest of it respectively. The reservoir was built in 1898 and covers an area of 20 acres.

In December 1969 there was a significant emergency when a crack was found in the reservoir wall, which led to the evacuation of 350 houses, 7 schools and the relocation of miners from Maerdy Colliery. Water was pumped out to reduce the reservoir water level by almost 10 metres to reduce the pressure on the structure and allow repairs to be completed. The emergency was declared over on 25 January 1970.