Lake Vyrnwy

Lake Vyrnwy is a reservoir in Powys, Wales. Its stone-built dam, built in the 1880s, was the first of its kind in the world. It was built for the purpose of supplying Liverpool and the districts later designated as Merseyside with fresh water. It flooded the head of the Vyrnwy valley and submerged the small village of Llanwddyn.

The reservoir is Severn Trent Water's largest. When full, it is 26 metres (84 ft) deep, contains 59.7 gigalitres (13.125×109 imp gal), and covers an area of 4.54 square kilometres (1,121 acres), the equivalent of around 600 football pitches. The lake has a circumference of 19 kilometres (12 mi) with a road that goes all the way around it. Its length is 7.64 kilometres (4.75 mi). On a clear day the lake, along with many others in North Wales, can be seen from space.