In 2004 the Gold Coast City Council resolved to construct Stage 3 of the dam . When the dam reached full capacity , on 7 January 2008 work began on Stage 3 and was completed on 19 December 2011 . After nearly four years of construction the construction cost was 395 million . The Stage 3 works increased the height of the dam wall from to , and increased the reservoir capacity from to , with the added purpose of flood mitigation , beyond water supply . Stage 3 construction was completed by the Hinze Dam Alliance , a joint venture between Seqwater , with private sector partners URS Corporation , Sinclair Knight Merz and Thiess . The additional works with a higher dam wall provided homes below the dam wall with flood protection from a 1974 Brisbanestyle flood event
1974 Brisbanestyle flood
1974 Brisbane flood
Hinze Dam