Powys Digital History Project

The Elan Valley dams
The source of Birmingham's water

The location of
the Elan Valley dams
and reservoirs
is shown on the
sketch map. 

High ground, high rainfall
There were a number of reasons for the choice of the Elan Valley district as the source of supply for Birmingham. The annual rainfall was high, and the valleys of the rivers Elan and Claerwen near Rhayader were narrower downstream, making it easier to construct masonry dams.

The city of Birmingham was built on relatively high ground, and the use of reservoirs constructed in the high moorlands of mid-Wales would allow the water supply to be fed by aqueduct on a suitable gradient by gravity alone, without the need for costly pumping.

The future site of
Caban Coch dam

Photograph by
kind permission of
Radnorshire Museum,
Llandrindod Wells

Site of Caban Coch dam Further factors in favour of the area were that the local bedrock was ideal for retaining the water held in the reservoirs, and also the relatively sparse population in what was a remote upland area. This lessened the task of securing ownership of over 70 square miles of the watershed.
Only the affected landowners, however, were to be given any financial compensation, and tenant farmers and smallholders, who needed it most, were evicted without recompense. Servants and other workers employed by the two large estates of Cwm Elan and Nantgwyllt also lost their income and their accommodation. It is likely that at least some of these were left with no alternative to Rhayader workhouse.


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".
Although remote, the flooding of the valleys led to the loss of two historic country houses, both briefly residences of the poet Shelley, and of a church, chapel, schoolhouse, and 18 cottages and farmhouses. Some 400 people were displaced by the Birmingham scheme.
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