Work on the dam began on 19 July 1962, however work stopped shortly after due to excavations which revealed the site was over a large area of soft kaolinised granite, which would require expensive foundations.

The dam was opened on 13 October 1967 by Sir John Carew Pole, whilst the Bishop of Truro, Dr Maurice Key blessed the reservoir.

By the opening in 1967 the valley behind the dam was completely flooded, 274 acres of farmland and three country houses became[clarification needed] submerged.

Two causeways were built to carry sections of roads that were flooded, one at the southern end and the other in the north western corner near the Golden Lion Inn.

Other activities include bird watching and fly fishing for trout.