Welsh Histories was recently checking out Cronfeydd Cwm Elan (Elan Valley Reservoirs). Here's a reel of our journey! Also, read on for some historical context: This is Cronfeydd Cwm Elan (Elan Valley Reservoirs) in Cwm Elan (Elan Valley), Powys. They consist of a chain of man-made lakes dating back to the late 19th century - when Afon Elan and Afon Claerwen were dammed. Built in 1893 and first flooded in 1896, Cronfeydd Cwm Elan consists of four main dams and reservoirs with a combined total cap