Lake Vyrnwy and Llanwddyn History


Lake Vyrnwy Nature Reserve and Estate (Welsh: Llyn Efyrnwy) ([pronounced [E]VURN-WEE]) is an area of land in Powys, Wales, surrounding the Victorian reservoir of Lake Vyrnwy. Its stone-built dam, built in the 1880s, is the first of its kind in the world.

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 old village of Llanwddyn in the head of the Vyrnwy Valley included 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 respectfully re-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 (population 300).

The village is very small, but still supplies for the many thousands of tourists which visit the lake and reserve each year. It is equipped with cafes, an RSPB Shop, several gift shops which sell local crafts and produce.

Llanwddyn 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.

Early picture of the Lake Vyrnwy Dam

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 is 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 dam's length is 357 m (1172 ft), 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) that 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 an electrical generator which is driven by water leaving the reservoir. Before mains electricity arrived in the 1960s this was Llanwddyn's only source of power.

The West and East Towers release compensation water by huge valves, which are controlled by Severn Trent Water. 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 were those built in the Elan Valley.


Approximately 1000 m/3500 ft from the dam is the reservoir's straining tower.

Standing only 30 m (100 ft) from the shore its purpose is to filter or strain out material in the water with a fine metal mesh, before the water flows along the aqueduct to Liverpool.

The sixty-eight miles of aqueduct bringing water from Lake Vyrnwy to Liverpool, and part of extensive works that also involve Britain's first high masonry dam at Vyrnwy.

The aqueduct originally consisted of two pipelines, made largely of cast iron. To help maintenance work on the 9ft diameter cast-iron tunnel which took the aqueduct under the Mersey, the riveted steel piping was also used.

This was an early use of the material which was to become the norm for trunk water mains piping.

Brick and concrete lined tunnels carried pipes at Hirnant, Cynynion and Llanforda, and a fourth later added at Aber so that the Hirnant tunnel could be made accessible for maintenance.

The first section of a third pipeline was laid in 1926-38 using bituminous-coated steel. To increase capacity, a fourth pipeline was added in 1946. Re-organisation of the pipe crossings beneath the Mersey and the Manchester Ship Canal were undertaken in 1978-81.

The current provision relies on three, 42in diameter pipes delivering up to 50 million gallons of water per day into reservoirs at Prescot, east of Liverpool.

The aqueducts carrying water away from Lake Vyrnwy to Liverpool was constructed across the valley for the reservoir between 1881-92.

It crosses the valley floor near Penybontfawr and then runs north of Llanrhaeadr-ym-mochnant and Efail-rhyd on the north-east of the Tanat Valley.

The aqueducts is largely hidden from view although there are a number of visible surface features including air valves, the Cileos valve house, the Parc-uchaf balancing reservoirs, and a deep cutting to the west of Llanrhaeadr-ym-mochnant.

In terms of the history of roads in the Tanat Valley it is interesting to note that complaints were made about damage to local roads during the construction of the Lake Vyrnwy reservoir.

Its architecture is Gothic and built during the same time as the dam. The tower as a whole is 63 m (206 ft) tall, 15 m (50 ft) of which is underwater. The other 48 m (160 ft) is above water, and is topped with a pointed copper clad roof, which makes it look light green.


The reservoir is Severn Trent Water's largest.

When full, it can take as much as up to 59,666 megalitres (13,000,000 gallons), and it covers an area of 4.53 square kilometres (1,121 acres) of land, the equivalent of 600 football pitches.

The lake has a circumference of 11 miles (18 km) with a road that goes all the way around it. Its length is 4.75 miles (7.6 km).

On a clear day the lake, along with many others in North Wales, can be seen from space.

There are 31 streams, waterfalls, and rivers that flow into the lake. Some are no more than a trickle, while other waterfalls cascade down the mountains. The 6 rivers that flow into the lake are all named respectively to the mountains or hillside it flows from. From the west side of the dam, clockwise, their names are: * Afon Hirddu * Eunant * Afon Eiddew * Afon Naedroedd * Afon Cedig * Afon Y Dolau Gwynion

On the Northern Edge of the lake is a small hamlet called Rhiwargor where the rivers Afon Eiddew and Afon Naedroedd meet. Up the valley of Afon Eiddew, there is an impressive waterfall, one of the largest surrounding the lake. Known locally as Pistyll Rhyd-y-meincau, it is commonly known as Rhiwargor Waterfall.

In 1889, shortly after completion, the lake was stocked with 400,000 Loch Leven trout.

The lake continues to supply Liverpool with fresh water.

It is also the water source used in the manufacture of Bombay Sapphire gin.


Lake Vyrnwy is a Nature Reserve.

The RSPB has several bird hides around the lake, where several rare species of bird are known to be breeding, such as the Peregrin Falcon, the Pied Flycatcher the Redstart the Siskin and the Wood Warbler.

Every spring they host a Dawn Chorus tour.

Around 90 species of bird have been recorded to be breeding on the reserve, and six species of bat, including the pipistrelle and brown long eared bat. Butterfly species include Purple Hairstreaks, commas, and peacocks. Dragonflies include Golden Ringed, Common Hawker and Four spotted chaser.

They are restoring the Heather Moorland that grows on the mountains around the lake. This restoration of heather moorland is becoming increasingly common in Britain. The heather is usually burnt, cut, and the seeds collected to be sowed where the heather has gone.

This management of the moorland helps improve the habitat for Red Grouse and the Short-eared Owl. Sheep, cattle and ponies also graze on the heather.

Broadleaf trees are being planted in replacement of coniferous trees, and even manmade things are being restored, such as hedgerows and dry-stone walls. Wild flowers areas are also being restored to help insects, birds, and other wildlife.


In the valley below the dam, there is a Sculpture Park with dozens of wooden carved sculptures.

There are individual sculptures, which range from as far afield as Australia, and Eastern Europe. With many other sculptures placed at picnic sites around the lake itself.

For instance, there are large wooden benches in the shape of leaves and trees on the west side of the lake.

And near the Old Village on the beach is a sculpture of dolphins, which when the lake rises in a flood, gives the impression that they are jumping out of the water.

Several totems can be seen hewn from trees, which have collapsed but have been erected again.


Recreation Activities in the area include sailing, hiking on Glyndwr's Way, rock climbing, cycling and horseback riding.

There is also an annual Vyrnwy half-marathon run around the lake.


The River Vyrnwy (or Afon Efyrnwy) runs from the Welsh mountains; its sources are from many and varied streams and tributary rivers from around the lake.

However, since the valley was flooded, the river starts at the foot of the dam and flows east towards England, eventually finding its way to Shropshire where it converges with the River Severn near the village of Melverley on the Welsh border.

The river runs for 39.7 miles (64 km); the last 8 miles forms a natural boundary between England and Wales. The River Severn then takes its course though England to the Bristol Channel.