SNOWDONIA
Mountains hold many secrets. We journey back in time to one deadly night in the CARNEDDAU range of north Wales – the night of the Dolgarrog dam disaster.
For many years, I’ve felt a deep fascination with the Carneddau mountains, particularly the eastern area. As well as the phenomenal mountain architecture and a quieter feel to many other parts of the National Park, it’s the remnants of the Llyn Eigiau dam that intrigue me. Their man-made lines are at odds with the rugged randomness of all that surrounds them. Little did I know what I was about to find out about humankind’s efforts to control nature.
According to contemporary accounts it was a dark, stormy night on the 2nd of November 1925 when disaster struck the town of Dolgarrog. Ten adults and six children died. You won’t be surprised to learn the town is downstream of the above mentioned dam. But the story is a little more complicated than you may think.
The reservoir up in the Carneddau mountains’ Cwm Eigiau was built to supply a hydro-electric power plant, which serviced the large aluminium factory in Dolgarrog. It was this major employer to the area that was responsible for the village’s expansion into something resembling a town.
Dolgarrog reputedly got its name from ancient folk tales of a flying dragon called Y Garrog that lived close by. It was, of course, eventually slain. Dolgarrog was a much smaller place back then, made even smaller a couple of centuries later when the Black Death swept through the area. From the beginning of the 18th century, industry slowly consumed and expanded the locality of Dolgarrog, increasing the population and demands for water. The Eigiau reservoir had been built with surprisingly feeble looking walls. But it was the lack of depth to the foundations that caused the trouble.
Over the years, water started to leak under the dam and its shallow foundations. The dry summer and a wet autumn of 1925 did their worst. A huge, rectangular hole opened up in the ground where it was leaking. The dam wall and even the foundations were still intact, spanning the gaping, deadly chasm. The water poured into the catchment of Afon Porth-llwyd, the river below the dam. This was the first in a two-part disaster. Below the Eigiau reservoir was a smaller one, Coedty reservoir. This had, and still has, an embankment dam, a far more substantial construction than the flimsy wall of Eigiau’s gravity dam. Coedty reservoir quickly started to overspill, then the soil and rock structure of the embankment gave way, sending a mind-boggling amount of water and a huge number of enormous boulders into the steep gorge above Dolgarrog.
Things could have been much worse. As it
