Construction of the dam started in 1900 by the Douglas Corporation Water Works Department.

A railway was first built, including nine wooden bridges over the River Glen, to transport the required material to site.

There is a vertical puddle clay core supported by zoned earth fill shoulders.

The higher part of the upstream shoulder is faced in dry rubble pitching about 60 centimetres (2 ft) thick.

[1] The reservoir supplies Douglas, Onchan and the south of the island.