Photo [IMG_0622] of Caban-Coch Reservoir
Photo [IMG_0632] of Claerwen Reservoir
Photo [IMG_0489] of Llwyn-Onn Reservoir
Photo [IMG_0763] of Llanishen Reservoir
Photo [IMG_0856] of Llyn Efyrnwy
Photo [IMG_0859] of Llyn Efyrnwy
Llyn Efyrnwy in Powys

Llyn Efyrnwy

Llyn Efyrnwy is a reservoir situated in Montgomeryshire, Powys.

Its stone-built dam constructed in the 1880s was the first of its kind in the world. Vyrnwy was the first dam to carry water over its crest instead of in a channel at the side.

When built it cost £620,000, which today is around £22,000,000.

The dam is 44 metres (144 ft) high from the bottom of the valley, and 39 metres (128 ft) thick at the base; it is 357 metres (1,171 ft) long and has a road bridge running along the top.

It is decorated with over 25 arches and two small towers (each with four corner turrets) rising 4 metres (13 ft) above the road surface.

Depending on the Water Levels downstream the reservoir could release anything from 25 to 45 megalitres (5,500,000 to 9,900,000 imp gal) of compensation water per day.

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