Black and white photograph of the Elan Valley Water Scheme taken at the time of construction, showing view of a stone-laying ceremony, watched by many gentlemen in railway wagons lettered BCWW.

The dams, reservoirs, tunnels and 117 km aqueduct of the Elan Valley Water Scheme in mid-Wales were built to supply clean water to the city of Birmingham in the English midlands. Construction of this ambitious civil engineering project in the rugged terrain of mid-Wales lasted in total for thirteen years, from 1893 to 1906. The work was substantially complete when the scheme was officially opened by King Edward VII and Queen Alexandra on 21 July 1904. The scheme is still supplying Birmingham's water: it was expanded in the mid-twentieth century by the construction of another dam on the Claerwen river, thus doubling the capacity of the original scheme to 345.5 million litres of water per day.