On 7 August 1896 the tunnel's inlet valve was opened by the Governor of South Australia, Sir Thomas Fowell Buxton and the reservoir began filling.

[5] Initially 15 kilometres from Adelaide, the reservoir is now largely enveloped by the city's southern suburbs, of which the relocated Happy Valley village is now one.

In the early 2000s, plans to harvest the mature pines were blocked following public protests over the visual impact the clearance and replanting would have on the surrounding suburbs.

Part of this project included an upgrade of the dam wall designed to also increase flood storage capacity by 165% and reduce the risk of damage in the event of an earthquake.

[8] With the lowering of the water level during renovations exposing the original Happy Valley township for the first time, archaeologists took the opportunity to excavate the site.

[10] The reservoir was opened to the public on 11 December 2021 for the first time in more than 120 years, after a network of trails and other facilities were built by the state government.