We own and operate 26 dams, 51 weirs, and two borefields across the region. Twelve key dams across the region supply as much as 90% of South East Queensland’s drinking water.
Water from our dams is released to supply our drinking water treatment plants and irrigation schemes, as well as to ensure environmental flows in downstream rivers and creeks.
While our dams primary purpose is water supply, many of them also provide the community with recreation facilities, both on the water and in the areas around the lakes.
Somerset Dam and Wivenhoe Dam both have additional flood storage compartments above their drinking water storage capacity. During times of heavy rain, we are able to store additional water in these dams and make controlled releases in order to reduce the volume of water flowing down the Brisbane River. Around 50 per cent of the Brisbane River Catchment is below Somerset and Wivenhoe Dams, including the Bremer River and Lockyer Creek. This means their flows cannot be controlled by our dams.
North Pine Dam doesn’t have additional flood storage capacity, but by using controlled gate releases we are able to mitigate the flow of water and reduce river levels downstream of these dams.
The rest of the dams in our region are un-gated. When un-gated dams reach 100 per cent of their capacity water begins to flow over the dam wall, down a spillway. The spillway of each dam is at a lower height than the dam embankment so that flood water can flow over the spillway and safely out of the dam. These structures are not designed to hold flood water, and cannot be operated for flood mitigation purposes. However, these un-gated dams still reduce peak outflows by holding back water in the dams while they are spilling.
Visit the Dam Release Updates page for the latest information on gated releases and un-gated dams spilling.
Dam optimisation studies
The Department of Energy and Water Supply has announced the new flood mitigation strategies for the operation of Wivenhoe, Somerset and North Pine dams, as a result of the optimisation studies and public consultation.
In April 2014, the department released the Wivenhoe and Somerset Dam Optimisation Study and the North Pine Dam Optimisation Study for public discussions. The studies were completed in response to the Queensland Flood Commission of Inquiry to investigate potential alternative operations of the existing dams during floods.
More information on the Wivenhoe and Somerset Dams Optimisation Study or the North Pine Dam Optimisation Study is available on the Department of Energy and Water Supply website. View our updated manuals of operational procedures for flood mitigation for Wivenhoe Dam and Somerset Dam, and North Pine Dam.