Powys Digital History Project

The Elan Valley dams
Plans for a 'High Dam',1973

1973 proposal
for a huge
gravity dam at
Craig Goch

Craig Goch dam at risk
In the early 1970’s design studies were commissioned into the feasibility of a huge new ‘High Dam’ at Craig Goch, the site of the highest of the existing Elan Valley dams. The new dam, which would greatly increase the reserves of water available for supply, was required to be brought into service by the summer of 1981.
Proposals were put forward for several types of dam structures up to 310 feet (95m)highDrawing of new gravity dam,1973 and which would have created an enormous reservoir (see map below) at a maximum top water level high up in the watershed at 1263 feet (385m).
The original Craig Goch dam designed by James Mansergh in the 1890's had been built at the most suitable dam site in that part of the Elan Valley. Most of the replacement dams submitted were for a site just downstream of the original, and they would either have completely submerged the old dam under the waters of the new reservoir as in the version above left, or have buried it during the course of construction.
The drawings, map and
details of the Craig Goch
project on this page are
from a feasibility study
prepared by
Sir William Halcrow
and Partners in 1973.
One particularly spectacular variant of the options suggested, Drawing of new arc dam,1973however, was for a huge arc dam located just upstream of the 1890’s structure, leaving the original intact. The drawing of this version (right), illustrates the enormous scale of the 'High Dam' by showing the old dam completely dwarfed by the new structure. 
There was no suggestion of copying the 'Birmingham Baroque' style of the early dams, as was done with the Claerwen dam of 1952. Though built of concrete, this dam was faced with dressed stone at considerable extra cost to be in keeping with the much older structures nearby.

 The extent of
the reservoir which
would have
resulted from
a large new dam
at Craig Goch

County Archives

Sketch map of larger reservoir,1973The report put forward in 1973 commented, of the original Elan Valley dams, that "at the time of their construction these structures were technological achievements of the highest order. A new and higher dam at Craig Goch would, in our view, best be designed in a style appropriate to its size and the times in which we live".

The sketch map (left) shows the existing Craig Goch reservoir in light blue surrounded by the darker blue of the new expanse of water which would have been created if the 'High Dam' had gone ahead as proposed.
Although the plans suggested in the 1973 report were taken forward to a fairly advanced stage of planning, a massive new dam was not built at Craig Goch, and the graceful hundred-year old stone structure still survives intact and plays its part in supplying water to the City of Birmingham.

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