Llyn Eigiau is a lake on the edge of the

Carneddau The (lit. 'the cairns'; is a Welsh plural form, and is sometimes anglicised to ''Carnedds'') are a group of mountains in Snowdonia, Wales. They include the largest contiguous areas of high ground (over or high) in Wales and England (although l ...

range of mountains in

Snowdonia Snowdonia or Eryri (), is a mountainous region in northwestern Wales and a national park of in area. It was the first to be designated of the three national parks in Wales, in 1951. Name and extent It was a commonly held belief that the nam ...

Conwy Conwy (, ), previously known in English as Conway, is a walled market town, community and the administrative centre of Conwy County Borough in North Wales. The walled town and castle stand on the west bank of the River Conwy, facing Deganwy on ...

, Wales. The name ''Eigiau'' is thought to refer to the shoals of fish which once lived here. Early maps refer to it as ''Llynyga''. It is thought that a small number of

Arctic char The Arctic char or Arctic charr (''Salvelinus alpinus'') is a cold-water fish in the family Salmonidae, native to alpine lakes and arctic and subarctic coastal waters. Its distribution is Circumpolar North. It spawns in freshwater and populatio ...

exist in the lake (as they do in neighbouring

Llyn Cowlyd Llyn Cowlyd is the deepest lake in northern Wales. It lies in the Snowdonia National Park at the upper end of Cwm Cowlyd on the south-eastern edge of the Carneddau range of mountains, at a height of above sea level. The lake is long and narrow ...

) after they were transferred here from

Llyn Peris Llyn Peris is a lake in Snowdonia, Wales, approximately 1.8 km long and situated close to the villages of Llanberis and Nant Peris, and the smaller twin of Llyn Padarn. The lake was formed glacially and is an example of a moraine-dammed la ...

, and certainly it is one of the few lakes in Wales to have its own natural

brown trout The brown trout (''Salmo trutta'') is a European species of salmonid fish that has been widely introduced into suitable environments globally. It includes purely freshwater populations, referred to as the riverine ecotype, ''Salmo trutta'' morph ...

. The lake is surrounded by mountains including

Pen Llithrig y Wrach Pen Llithrig y Wrach is a mountain peak in Snowdonia, Wales. It is one of the four Marilyns that make up the Carneddau range. To the east is Creigiau Gleision, another Marilyn, while to the west is Pen yr Helgi Du and Carnedd Llewelyn. Crai ...

Dam

In 1911 a dam ¾ mile long and high was built across part of its eastern side to supply water for the power station at

Dolgarrog Dolgarrog is a village and community (Wales), community in Conwy County Borough, in Wales, situated between Llanrwst and Conwy, very close to the Conwy River. The village is well known for its industrial history since the 18th century a ...

, which in turn provided power for the adjacent

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...

works. Materials for the dam were transported along the newly laid Eigiau Tramway, which ran from Dolgarrog and utilized the route of the former Cedryn Quarry Tramway. The original contractor pulled out of the construction, alleging corner-cutting, and indeed on 2 November 1925, following of rain in just five days, the dam broke. The water flowed down to

Coedty Reservoir Coedty Reservoir is a reservoir in Snowdonia, North Wales. It is fed by the waters of Afon Porth-llwyd which flows from Llyn Eigiau. The reservoir lies at a height of , and measures some in size. It contains brown trout. The original dam was ...

, also causing that to burst, and millions of gallons of water flowed down into the village of

, causing the loss of 16 lives. A new power station was built at Dolgarrog in 1925. Three short black and white silent films of the incident exist. A study of the dam today shows that the foundations were insufficient, and large lumps of unmixed cement can also be seen. The dam material that can be seen through existing holes is flaky and tends to break away easily.

Present-day

Today the lake covers an area of about , and has a depth of about . After the construction of the dam its area would have been twice this. Water is fed into Llyn Eigiau by a tunnel from the stream below

Llyn Dulyn Llyn Dulyn ( cy, black lake) is a lake on the edge of the Carneddau range of mountains in Snowdonia, North Wales. The lake is in extent and 189 feet (58 metres) deep. Less than a kilometre to its south lies the smaller Llyn Melynllyn. Cliffs ri ...

, and another larger tunnel takes water from Llyn Eigiau to

. The main feeder of Llyn Eigiau is

Afon Eigiau Afon Eigiau is a small river in the Carneddau mountains in Snowdonia, in north-west Wales, which flows down Cwm Eigiau and into Llyn Eigiau. It is fed by smaller streams which flow down the slopes of neighbouring Foel Grach Foel Grach i ...

, a small river which flows down Cwm Eigiau. The outflow from Llyn Eigiau is called

Afon Porth-llwyd Afon Porth-llwyd is a river in Snowdonia in north-west Wales. It flows from Llyn Eigiau on the south-eastern edge of the Carneddau range to join the river Conwy. Its waters are trapped at Coedty reservoir before flowing down to pass under Pont ...

, and this flows via

Coedty reservoir Coedty Reservoir is a reservoir in Snowdonia, North Wales. It is fed by the waters of Afon Porth-llwyd which flows from Llyn Eigiau. The reservoir lies at a height of , and measures some in size. It contains brown trout. The original dam was ...

before passing under Pont Newydd in Dolgarrog. This then flows into the

River Conwy , name_etymology = , image = Boats in River Conwy.jpg , image_size = 300 , image_caption = Boats in the river estuary at Conwy , map = , map_size = , map_caption = , push ...

Access

Although private vehicles are not permitted access to the lake itself, there is a carpark within walking distance, approx. half a mile from the dam and which is reached by road from the B5106 at Tal-y-bont, in the

Conwy valley , name_etymology = , image = Boats in River Conwy.jpg , image_size = 300 , image_caption = Boats in the river estuary at Conwy , map = , map_size = , map_caption = , push ...

. The road passes through

Llanbedr-y-Cennin Llanbedr-y-Cennin is a small village in Conwy county borough, Wales, in the community of Caerhun. It lies in the foothills on the western side of the Conwy valley, in Wales. The river Conwy runs through the valley, running into the sea to the n ...

and thereafter becomes a narrow lane as it goes over the hills towards the lake. Along this lane there are some public footpaths signposted, with stiles to access them over the old dry-stone walls that run along parts of the lane.

Bibliography

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References

{{authority control Caerhun Eigiau Eigiau Dam failures in Europe