Construction of the dam commenced in 1932 and was completed in 1938 at a cost of 1.1 million. The concrete dam wall is high and long. When full, the reservoir has capacity of and covers , drawn from a
catchment area of . The
controlled spillway has a flow capacity of . The reservoir does not connect directly to the main reticulation system; rather, to maintain levels at
Clarendon Weir, water is released only as required. Much of the water from Mount Bold will eventually end up in the
Happy Valley Reservoir and used to supply parts of the
Mount Lofty Ranges and also Adelaide. A major renovation was completed in 1964 when the level of the dam was raised to increase the reservoir's capacity by approximately . Although originally supplying its own electricity through a small conventional
hydro-electricity plant, this was discontinued in 1961. However, Mount Bold is now considered a possible site for a future commercial
mini-hydro generator. In early June 2007, the
South Australian Government began a scoping study into expanding the reservoir's capacity fivefold to at an estimated cost of A$850 million. The plan was criticised by the
Opposition as not providing any new water, and by ecologist David Paton as threatening surrounding wildlife. On 26 September 2010, Mount Bold Reservoir was opened for the first time since 2005 after receiving large amounts of rainfall in the week leading up to the date. The resulting water flushed out the Onkaparinga Catchment, causing several flooded roads but removing debris which had been building up for many years. ==2007 fire==