The contractors, Edmund Nuttall, Sons and Co. (London) Ltd., provided a temporary camp for 200 of them, with bungalows for members of the staff.

Claerwen National Nature Reserve is an expanse of mountain upland lying halfway between Rhayader in Powys and Pontrhydfendigaid in Ceredigion.

The mainly peaty and acidic soil provides an environment which is home for many species of plants and animals which thrive in these conditions.

These include the nationally scarce water plantain (Luronium natans) as well as carnivorous plants such as Drosera rotundifolia, and butterworts.

In 2015 the dam was featured in the fourth episode of series twenty-two of the BBC motoring programme Top Gear.