Caban-coch is the lowest of the four dams built in the valley of the Elan River. It was the nearest dam to Rhayader and it was the first to be started, because the railway line used to deliver the building materials reached this site by May 1894.

This picture is taken from
an old 'Magic Lantern' image
on a glass slide.
It shows building work on
the top of Caban-coch dam
in 1901.

You can see some of the
big steam-driven cranes,
and tracks for the railway
wagons carrying building
material at different levels
on the side of the valley.

For all the dams the first stage meant blasting with explosives and digging in to the valley sides to get strong foundations for the huge stone walls which would hold the water in the valleys.

The dam-building scheme had to make sure that the rivers below the Elan, including the River Wye, still had enough water to keep them flowing normally. This was called 'compensation water' and Caban-coch dam was designed to supply this. The buildings below the dam, seen in the 1908 photograph above, had valves and sluices to control the flow down the river. They also contained turbines to make electricity from the flow of the water.
You can see another photograph of Caban-coch dam on one of the pages on the Elan Valley Railway.

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