Lake Vyrnwy Dam
Lake Vyrnwy Nature Reserve and Estate (or Llyn Efyrnwy/Fyrnwy in Welsh) [pronounced VURN-OOE] is an area of Land in North Wales, Powys, surrounding the Victorian reservoir of Lake Vyrnwy. Its stone built dam is the first of its kind in the world and was built in the 1880s. The Nature Reserve and the area around it are protected by the Royal Society for the Protection of Birds, and Severn Trent Water. It was built for the purpose of supplying Liverpool and Merseyside with fresh water. It flooded the head of the Vyrnwy Valley and submerged the small village of Llanwddyn. Today it is a popular retreat, for people in the West Midlands and Merseyside for days out, and also for ornithologists, cyclists, and hikers. The Reserve is designated as a National Nature Reserve, a Site of Special Scientific Interest, a Special Protection Area, and a Special Area of Conservation.
The village of Llanwddyn
The old village of Llanwddyn in the head of the Vyrnwy Valley comprised off a post office, an inn and parish church just like other Welsh villages of its time. People still lived in the village as the dam was being constructed, and down the valley in front of the new dam the Liverpool Corporation built the new village ready for when the valley was going to be flooded. In all two chapels, three inns, ten farmhouses, and 37 houses were all to be lost under reservoir. Even the remains of bodies from the chapel's cemeteries were removed before the flood, and respectively buried in the new church cemetery. Also lost under the water was Eunant Hall, a large house and estate owned by a member of the local gentry. Along with all the other buildings behind the dam this also was demolished, though no new Hall was built. The old village can still be seen during drought conditions when the reservoir is very low, and the foundations of several buildings still survive.
The village has been relocated and is now at two locations: on a slope adjacent to the dam, and at the bottom of the valley below the dam. The new village was built approximately 2 miles away and still keeps the name Llanwddyn.
The village is very small, but still supplies for the many thousands of tourists which visit the lake and reserve each year. The village is equipped with cafes, an RSPB Shop, several gift shops which sell local crafts and produce, and a Tourist Information Centre which sells booklets and pamphlets not just on the Lake but for most of North Wales and Snowdonia. The village is in a prime location for tourists, as it is near the border of Snowdonia National Park, and lies between the Cambrian Mountains and the Berwyn range.
The Dam was started in 1881 and completed seven years later in 1888, it was the first large stone-built dam in the United Kingdom, and it built partly out of great blocks of Welsh Slate. When built it cost £620,000, which today is around £22,000,000. The dam is 44 m (144 ft) high from the bottom of the valley, and 39 m (127 ft) thick at the base. The dams’ length is 357 m (1172 ft), and has a road bridge running along top. It is decorated with over 25 arches and two small towers which rise 4 m/13 ft above the road surface.
Vyrnwy was the first dam to carry water over its crest instead of in a channel at the side. At the bottom of the dam is a body of water known as the Stilling Basin, this is necessary to absorb the energy when the water flows over the crest and into the valley, and stops the water from eroding the foundations of the dam.
Underneath the West Tower is a building known as the Power House. Inside is a electrical generator which is driven by water leaving the reservoir. Before mains electricity arrived in the 1960s this was Llanwddyn only source of power.
The West and East Towers release compensation water by huge valves, which are controlled by Severn Trent. This water is purely for the River Vyrnwy, which would otherwise dry out unless in flood. Depending on the Water Levels downstream Severn Trent release anything from 25 to 45 megalitres (5.5 to 10 million gallons) of compensation water into the River Vyrnwy each day. Only a few hundred yards downstream is a weir, which the Environment Agency use to measure the daily amount of compensation water. This weir also holds back enough water to create the stilling basin.
Earlier dams in Britain had been built by making great earth embankments to hold back the water, this new type of stone dam would change the face of the Welsh Landscape over the coming years, the next stone dams to be built in Wales on an even bigger scale than Vyrnwy was those built in the Elan Valley.