Conception

The site was identified in a 1990 study, Water Supply Sources in South-East Queensland, as a future source of water supply for the South East Queensland region. In this report, the site of Wyaralong Dam was ranked 13th out of 15 studied possible dam locations in the region. A location on the Albert River at Glendower, also near Beaudesert, was the preferred location and the government subsequently bought back all the land required for the Glendower Dam. A new dam was not expected to be required until 2060 or later and Glendower Dam remained the preferred dam site, the land already fully government owned.^{[citation needed]} Properties previously acquired by the government are progressively being sold to private buyers.^[8][9][10]

In October 2005, in advance of the state election, the Queensland government announced Wyaralong Dam as the new preferred option, even after recent studies into possible dam locations found a location upstream on the Logan River to be a more reliable option. After a series of studies, a Senate Inquiry and much contested information, Federal Environment Minister Peter Garrett granted approval for the Wyaralong Dam in November 2008.^[11]

The dam is a storage and regulation facility. It does not discharge directly into the piped reticulation network, but rather discharges back into the natural drainage network of creeks and brooks. Water released from the dam flows downstream along Teviot Brook to Cedar Grove Weir, where it is diverted for treatment and use in the piped network.

Construction

The construction was tendered under an alliance contract. In this type of contract risks and rewards are shared by all the proponents including designers constructors and the owner. Queensland Dam Consortium won the tender for the dam's construction, and the Alliance was formed from their members which included Macmahon Construction as the lead contractor, Hydro Tasmania, Snowy Mountains Engineering Corporation, Paul Rizzo and Associates (USA), ASI Contractors (USA) and Queensland Water Infrastructure the special purpose vehicle created by the Queensland Government owner to deliver the project.^[6] The Alliance contract for dam construction was for a little over A$100 million. However it was widely reported that the building costs for the dam would total A$333 million.^[12] The latter figure includes the cost of the Bromelton Offpeak Storage Project, Cedar Grove Weir and the reconstruction of a length of the Boonah to Beaudesert Road.

Work on access roads began in early 2009 and construction of the dam wall began in early 2010.^[12] The diversion channel was plugged on 17 December 2010, allowing the dam to begin to fill.^[13] The dam site was opened to the public on 3 June 2011.^[14] The 12 kilometres (7.5 mi) of new road between Boonah and Beaudesert were constructed under a separate contract by Fulton Hogan.^[6]

The dam cost A$380 million to construct, including purchasing farmland flooded by the dam reservoir.^[15]

Treatment

By late 2012 the dam still had not been connected to the SEQ Water Grid because it contains water so mineralised it is cheaper to produce desalinated water than to treat it.^[15] The Wyaralong water treatment plant is expected to cost A$235 million to construct.^[16] Funding for the plant was planned for the 2014/15 financial year. In 2017 SEQ Water external relations manager Mike Foster stated the Wyaralong Water Treatment Plant wouldn't be necessary until "2030 or beyond".^[17]