Llyn Cowlyd is the deepest lake in North Wales. It lies in the Snowdonia National Park on the edge of the Carneddau range of mountains, at a height of 1164 feet above sea level. The lake is long and narrow, measuring nearly 2 miles long, and about 1/3 of a mile wide, and it covers an area of 269 acres. It has a mean depth of 109 feet and at its deepest has given soundings of 229 feet, this being some 45 ft greater than its natural depth, the water surface having been raised twice by the building of dams.
The surrounding hills drop steeply to the water's edge and as a consequence have not been forested in the 20th century, as were the slopes of neighbouring Llyn Crafnant. Indeed there is not a tree to be seen, and the general aspect is one of bleakness. Dependent on the weather conditions, the waters often appear dark.
The supply of water to Llyn Cowlyd is assisted at its south-western end by a leat which runs roughly east-west along the 1370' contour to the south and west of the lake, along the Ogwen Valley. It is also fed by water from Llyn Eigiau.
Llyn Cowlyd can be reached by road from Trefriw, some 3 miles to the east, although the metalled road stops at a gate, the best part of a mile from the lake itself, beyond which private vehicles are not permitted. Llyn Cowlyd can also be reached by foot from Capel Curig, some 2 miles away. A good path runs along the north-western shore of the lake.
The stream which flows from Llyn Cowlyd is called Afon Ddu. This flows into the River Conwy, passing Pont Dolgarrog on the B5106, just south of the village of Dolgarrog. The gorge cut by the river at this point is popular for gorge walking.
Origins of the name
Some sources state that the name Cowlyd comes from "Cawlwyd" (meaning unknown).
The Ordnance Survey map of 1841 records the name as "Cwlyd", as does the National Gazetteer of 1868.
Other research has suggested that the name might derive from Caw ap Geraint Llyngesog ab Erbin ap Custennin Gorneu ap Cynfor ap Tudwal, the famous warrior who features in Culhwch and Olwen. Caw's son Celyn ap Caw, was based at Garth Celyn, on the edge of the Menai Strait, and had a watchtower, Tŵr Celyn, near the Copper mountain, on Anglesey.
The lake is a reservoir, having a 30' high dam at its north-eastern end, which consists of a rock and earth embankment with a concrete core. A concrete and stone apron protects the dam from wave action, which comes from the direction of the prevailing winds. The dam, which replaced a lower, earlier one, was completed in 1921, and it was officially opened on 20th September, 1922. The lake provides water for the towns of Conwy and Colwyn Bay, having been purchased for £55,000 by the Conwy & Colwyn Bay Join Water Supply Board, a company set up in 1891, via a pipe network some 40 miles long. However, these pipes are underground, their presence only given away by the chamber covers at Siglen, and the occasional isolated pump-house along the route. These water supply pipes should not be confused with the large (5' 10" diameter) black pipeline which runs for 5 miles from the dam to Dolgarrog, and serves the power station there, built in 1925, to support the aluminum works. During World War II a shepherd called Wil Roberts was paid a nominal sum of money to check the pipeline for bomb damage or any signs of sabotage. His only find was a crashed Anson aircraft in February 1944.
Llyn Cowlyd is one of two reservoirs which supply hydro-electricity to the aluminium works at Dolgarrog. The other is Llyn Eigiau, which was physically connected to Llyn Cowlyd by a tunnel in 1919, and this is the water which flows into the lake by the dam. Water also flows from Llyn Eigiau more directly to Dolgarrog via Afon Porth-llwyd and Coedty reservoir. Llyn Eigiau lies a mile to the north of Llyn Cowlyd, and its water rights were at the time owned by the Aluminium Corporation Limited.
The history of electricity production at Dolgarrog is tied up with that of Henry Joseph Jack (1869-1936), who was chairman of the North Wales Power and Traction Co. Ltd, and who had a dream of using this new power source to power the narrow gauge railways in North Wales. The NWPTC was the company behind the Portmadoc, Beddgelert and South Snowdon Railway (to later become the Welsh Highland Railway) and he became Chairman of the Festiniog Railway during July 1921, putting him in control of all the passenger carrying narrow-gauge railways of that part of North Wales. In addition to this, in 1922 he became a director of the Snowdon Mountain Railway which was also part of the Dolgarrog empire.
During construction of Cowlyd dam, electricity for the winches was provided by the North Wales Power and Traction Co. Ltd's power station at Cwm Dyli, near Snowdon. The remains of the pole route along the western shore of the lake can be seen today.
Llyn Cowlyd Tramway
Construction of the dam, which was built entirely from rock quarried from the adjacent mountainside, was assisted by the construction of a narrow gauge 2ft gauge railway line, known as the Llyn Cowlyd Tramway, which was used to convey men and materials to the reservoir for construction and subsequent maintenance purposes. The line ran from near Coedty reservoir, above Dolgarrog, largely parallel to, and to the north of Afon Ddu, up as far as the dam. The tramway was essentially a branch line of the former standard gauge Eigiau tramway, built to serve Llyn Eigiau, and itself a successor to the narrow gauge Cedryn tramway.
The construction of the Cowlyd - Eigiau water tunnel gave rise to a temporary extension to the tramway.
Construction of the Cowlyd Tramway began in 1916 and the dam was completed in 1921. During this time the Eigiau tramway was also converted back to narrow gauge. The tramway was connected to the works at the valley bottom by a rope worked incline which was extremely steep. Two steam engines were used to build the line - the German built loco Eigiau (Orenstein & Koppel, No. 5668 of 1913, latterly at Penrhyn Quarry, and a Bagnall 0-4-0ST, Works No.2080 of 1918.
Upon completion of the dam, and with only maintenance work being envisaged, Eigiau was taken off, pending sale, and a Simplex diesel loco, Motor Rail 22154 Dolgarrog was acquired in 1922. This was later used in the 1970s to lay power cables alongside the Llanberis Lake Railway, this being followed by a spell on display in the Dolgarrog Power Station Museum, together with some wagons from the tramway. "Dolgarrog" is currently on loan from Innogy - owners of Dolgarrog Power station, and in whose colours it is painted - and is being used by the revived Welsh Highland Railway in the reconstruction of the narrow gauge line from Caernarfon to Porthmadog. This loan to the WHR is not without precedent - back in 1922/3 the original Welsh Highland construction contractors also made use of a steam locomotive which had previously been used here, namely the Bagnall.
In 1936 a new diesel tractor was acquired, a Simplex (Hibbert, No.1988 of 1936) and this was replaced by new Motor Rail tractor, No.22154 of 1962.
The tramway closed temporarily in 1968 after a derailment of a workmen's train, but in fact it never re-opened as it was deemed unsafe. The approach road from Trefriw, which had been extended in the mid-1960s anyway to a point close to the pipeline, was now simply extended further so that necessary vehicles could reach the reservoir. It is reported that insufficient time and money had been spent on the construction of the line, which was of generally poor quality.
Today the route of the line is clearly evident. Where the metalled Trefriw access road ends at the gate, at Siglen, the route of the line between here and the dam runs higher up than the current access track, meaning that much of the formation has largely been untouched, and therefore much can be seen in the way of trackbed remains, including sleepers and rail. It is also apparent from these remains that the formation was, indeed, in places, of minimal standard. In the other direction, between Siglen and Coedty, the formation has been widened to form an access track (for farm and pipeline vehicle access) and on these widened sections the rail has been recovered, leaving only minimal evidence of the line. Today the whole length of the tramway can easily be walked, particularly between Siglen and the top of the Dolgarrog incline. It will be seen that the formation was of better construction towards Coedty, where there is an embankment and some small cuttings.
The loco shed is still evident near Coedty reservoir, at the point where the Cowlyd tramway branched off the Eigiau tramway. Also evident are the remains of the old incline, up which the engines were hauled.
It is commonly held that the rail used on some of the cattle-grids on the Trefriw to Cowlyd access road came from the former tramway, but comparison of the two reveals clearly that the tramway rail was considerably lighter, and would not be sufficiently heavy for this later use. It is more likely that it came from the Eigiau tramway, which at one time carried standard gauge engines, and would have been laid in heavier rail.
Failure of the Dam
During a storm on 31st December, 1934, there was a partial failure of the dam when the downstream side was washed out. The damage was kept fairly secret, and rebuilding it provided more useful work for the tramway.
This partial dam failure of the Cowlyd Dam should not be confused with that of the Dolgarrog Disaster of 1925 when the failure of the Eigiau Dam released water which went on to overtop the Coedty Dam, above Dolgarrog. This second dam also failed, releasing the huge volume of water that flooded Dolgarrog, killing 16 people.
Fly fishing (by permit) is permitted in the lake, which contains brown trout and Arctic Char (taken from Llyn Peris, in Llanberis).
Myths and Fables
According to The Mabinogion, the most ancient of Celtic literature written in the 14th century in the Red Book of Hergest, but orally dating back much further, the area was inhabited by more wildlife than seems to be there today. In one of the oldest stories, namely Culhwch and Olwen, Culhwch is obliged to perform some difficult labours, as set by the giant Ysbaddaden in order to win the hand of his daughter Olwen in marriage. In a smart move, Culhwch recruits King Arthur, his first cousin. One of the tasks is to find the lost Mabon, son of Modron, and a number of mythical beasts are consulted, one of whom is the Owl of Cwm Cowlyd. The owl narrates the history of its Cwm, and if any of it is to be believed, it confirms that the valley was once wooded (as was most of Snowdonia), but that the first clearing took place much earlier than mediaeval times, which is more unusual.
The following extract is taken from The Mabinogion -
So they proceeded to the place where was the Owl of Cwm Cawlwyd.
"Owl of Cwm Cawlwyd, here is an embassy from Arthur; knowest thou aught of Mabon the son of Modron, who was taken after three nights from his mother?"
"If I knew I would tell you. When first I came hither, the wide valley you see was a wooded glen. And a race of men came and rooted it up. And there grew there a second wood; and this wood is the third. My wings, are they not withered stumps? Yet all this time, even until to-day, I have never heard of the man for whom you inquire. Nevertheless, I will be the guide of Arthur's embassy until you come to the place where is the oldest animal in this world, and the one that has travelled most, the Eagle of Gwern Abwy."
Gwrhyr said, "Eagle of Gwern Abwy, we have come to thee an embassy from Arthur, to ask thee if thou knowest aught of Mabon the son of Modron, who was taken from his mother when he was three nights old."
The Eagle said, "I have been here for a great space of time, and when I first came hither there was a rock here, from the top of which I pecked at the stars every evening; and now it is not so much as a span high. From that day to this I have been here, and I have never heard of the man for whom you inquire, except once when I went in search of food as far as Llyn Llyw. And when I came there, I struck my talons into a salmon, thinking he would serve me as food for a long time. But he drew me into the deep, and I was scarcely able to escape from him. After that I went with my whole kindred to attack him, and to try to destroy him, but he sent messengers, and made peace with me; and came and besought me to take fifty fish spears out of his back. Unless he know something of him whom you seek, I cannot tell who may. However, I will guide you to the place where he is."
Another myth is that of the water bull who appears from the depths with -
Other tales talk of solitary walkers who have been dragged to their death, and of fairies, namely the Welsh Tylwyth Teg.
The poet R. S. Thomas makes reference to The Mabinogion's Owl of Llyn Cowlyd in his poem "The Ancients of the World".
The Ancients of the World
The salmon lying in the depths of Llyn Llifon
Secretly as a thought in a dark mind,
Is not so old as the owl of Cwm Cowlyd
Who tells her sorrow nightly on the wind.
The ousel singing in the woods of Cilgwri,
Tirelessly as a stream over the mossed stones,
Is not so old as the toad of Cors Fochno
Who feels the cold skin sagging round his bones.
The toad and the ousel and the stag of Rhedynfre,
That has cropped each leaf from the tree of life,
Are not so old as the owl of Cwm Cowlyd,
That the proud eagle would have to wife.
Gwilym Cowlyd (1828-1904), whose real name was William John Roberts, was a native of Trefriw, and one of the more colourful figures in Welsh culture and the Welsh Eisteddfod. He bardic name was taken from neighbouring Llyn Cowlyd.