Facts & Figures

Why was Lake Vyrnwy created here?

Lake Vyrnwy was created in the Berwyn Mountain range and lies just south of Snowdonia.

What was here before?

A century ago the Vyrnwy Valley looked very different, the valley of the River Vyrnwy was closed off by the building of the dam and the whole valley was flooded when the reservoir was filled. 

The creation of the lake involved relocating the former village of Llanwyddn. Farms and their land were also submerged below the water.  The village consisted of a Parish Church, two Chapels, three Inns, ten Farmhouses and 37 houses.

In dry summers the water level sometimes drops far enough for the ruins of the old village to be seen. 

The new settlement was built lower down the valley, even the graveyard was relocated along with the Church.

How long did it take to build the Dam?

The Corporation of Liverpool began work on the huge masonry dam in 1881 to secure a fresh water supply for Liverpool. 

The Dam was completed in 1888 and is 26m (84ft) high from the bed of the lake to the overflow.  The foundations are almost as deep again.  The Dam is 357m (1172ft) long and is 36.5m thick (120ft) at its base.

The lake took two years to fill and water was first supplied to Liverpool in 1891.  An official ceremony in 1910 was conducted by the then HRH the Prince of Wales to mark the completion of the works.

This dam was the first large masonry Dam built in Britain.  Earlier dams built in Britain had been earth embankment constructions. 

The surrounding 24,000 acre catchment area was also purchased to control the purity of the water.  This land now includes woodland walks, bird hides, viewing pointsand local crafts.  The RSPB shop provides information on which Bird species can be seen.

What is Lake Vyrnwy’s role in the water supply network?

The reservoir was created to provide drinking water for Liverpool.  The water is carried to the City of Liverpool by an Aqueduct.  The dam and reservoir were created when Liverpool was growing rapidly.  The new factories and mills of the Industrial Revolution were attracting workers to the area.  Clean water was required not only for the increased population, but for steam driven machines.

Where does the water come from?

The dam and reservoir are sited to take advantage of the Vyrnwy Valley and The River Vyrnwy.  The reservoir was filled by restricting the flow of the river behind the Dam.

The two stone towers on the top of the dam house the valves which control the ‘compensation’ water flowing from the base of the wall to allow the river to flow normally.

How deep is the reservoir?

The reservoir is 216 ft deep at its maximum depth.

The pointed tower is the ‘straining tower’ and is where the water leaves the lake on the start of its 70 mile journey down the aqueduct.  The water passessu through a fine metal mesh to remove large objects.

And how big?

Lake Vyrnwy is surrounded by a perimeter road which is 11.75 miles long.