Elan Valley – Welsh 100: No 40

It’s a little ironic that after the wettest December and January on record in Wales, that the three weeks before Aunty and I visit the Elan Valley there has been little rain. We would have loved to see the water cascading down the walls of the dams that make up the series of reservoirs in the Elan Valley, but it was not to be this Easter weekend. The weather for forecast is not good for the weekend as a whole, but Good Friday seems to offer the best weather with sunny periods all day. So we ventured forth from the caravan into the sun, but boy it was chilly still. Easter this year is early, but despite the sunshine the northerly wind still catches you around the nether-regions catching you unawares. Spring is here, but it seems that winter is not quite ready to leave go.

The Caban Coch Dam – not a drop cascading over the wall.

The Elan Valley, Cwm Elan, was once a farming community set deep in the hills of mid-Wales. A series of farms and small rural communities that maintained an independent, self-reliant lifestyle than while isolated due to distance was not isolated. That was until the needs of the all consuming industrial powerhouses of neighbouring England starting demanding more resources. The growing population, driven by the industrial needs of the Midlands was accompanied by the need for freshwater to combat disease from contaminated local water sources. It was not long after the completion of Llyn Vyrnwy that Birmingham started planing a series of more land grabs on the Welsh countryside, and a scheme  for the creation of yet another series of reservoirs to supply fresh water was conceived. The original reservoir scheme which allowed for some expansion envisaged seven reservoirs, of which four — Caban-coch, Garreg-ddu, Penygarreg and Graig Goch — were fully completed and one, Dolymynach, which was never completed.

The uplands around the reservoirs can seem bleak and remote, but this is what appeals to me.

But why choose the Elan Valley? For one it was relatively close to Birmgham, only 70 miles. It’s elevation above the city also meant that water could be delivered by gravity direct via the aqueduct without requiring the need for mechanical pumps. But perhaps the main reason was the high rain fall that occurs within the mountains for mid-Wales. A reality that many of us here in the west bemoan. However, Aunty having been born in England and lived the majority of her life in Wales loudly proclaims – “If they want our water they can pay for it!”


The original works building at the base of Caban Coch Dam. This is now houses a small hydroelectric generator.

The area of hills and valleys taken over by Birmingham City Council for their water supply was very thinly populated, but this didn’t mean that lives were not affected by the flooding of the valley to meet the needs of others many miles away. The hunger of industrial might elsewhere will always find victims. Displacement of local farmers and people resulted in the loss of 18 cottages and farms, a schoolhouse, a church were lost forever as the valley flooded. The small community of Nantgwylt now lies at the bottom of the flooded valley  near the meeting of the Rivers Elan and Claerwen. Shelley also lived here for a short time, but I’m not sure how much to lay on this. He seems to have lived in so many places. All in such a short life time. Perhaps he was the original Dr Who. Now there is a plot for the BBC!

Caban Coch Reservoir

 A member of the Water Committee wrote in 1892 – “The rainfall in these mountains is greatly in excess of that of our own district, owing to the nearness of the mountains to the sea and their lofty height. …With the exception of a very small portion of land under cultivation, and a small lead mine employing about 30 men, very high up in the mountains, the moorland waste is only tenanted by a few sheep farmers and their flocks“.

All very well for the landowners who were probably compensated for the loss of their land, but I am sure the tenant farmers and servants received no such recompense for the loss of their livelihoods. How many times has this happened in the past, and how many time will it happen in the future?

On the edge of Garreg-Du dam is the Victorian Nantgwyllt Church, built to replace the original church drowned by the reservoir.

The lowest of the dams is Caban Coch. This is the simplest in design and appearance and sits just above Elan Village (more on this later). When the reservoir is full water cascades over the walls like waterfall. But not today alas. The building of this dam and all the subsequent dams was dependent upon the creation of the Elan Valley Railway. This was required to transport the massive amounts of building materials and essential supplies needed at many sites, widely spread within the two river valleys. Eight saddletank locomotives were used to move about one thousand tons of building materials every day. The construction of each dam could only be started once the railway had reached that point. 

Carreg Ddu – this is in reality a submerged dam, and seems to run continuous with Caban Coch Reservoir.

 The next reservoir is Careg-Ddu. This seemingly runs continuous with Caban Coch but is in fact a low, completely submerged dam which plays a vital role in maintaining a constant supply of water to Birmingham. The dam has a road running across it towards Cwm Claerwen. 

The Foel Tower


The Foel Tower is the starting point of the 73 mile journey of the water from the Elan Valley to Birmingham. It was built in a style which, like many of the other structures of the waterworks scheme, has become known as ‘Birmingham Baroque’. This elegant stone tower houses a system of valves and cylinders which can be raised and lowered hydraulically to draw water off from the reservoir at various depths as required. This water is then directed into the start of the aqueduct, controlled by valves.



Excavation work on the foundations for the dam at Pen-y-Gareg began in April 1895, when the construction railway reached the site. Work on the masonry of the dam itself started at the end of the following year. 

Pen y Garreg Reservoir and Dam wall 

Higher still up the valley is the dam at Craig Goch, at 1040 feet above sea level it is the highest in the series of dams originally planned by the Birmingham Corporation. Work on excavating the foundations for a secure base for the structure started in July 1897, some three years after the start of work on the lowest dam at Caban Coch.

Looking down onto Craig Goch dam wall and reservoir.

 The last dam to be built is the Claerwen Dam and was finished in 1952. It has a simpler and more austere look, but there are attempts to make it blend in with the other dams built during the Victorian period. It is the largest reservoir in the Elan Vallay, and is almost twice as large as all the other reservoirs combined. The damn wall has a concrete core, dressed with stone. Due to the shortage of local stonemasons who were all engaged on rebuilding London after the war, it was necessary to employ Italian masons.

Looking up the expanse of the Claerwen Reservoir.











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