In June 2021, Sunwater temporarily reduced Callide Dam’s full supply and operational levels to allow for work to be completed as part of the Callide Dam Gates Project.
The top of the concrete spillway crest became the maximum height of the dam (100 per cent) and the temporary full supply level, and the operational level was set at 69 per cent.
As investigations and some of the work to resolve the gate vibration issue are now complete, the dam’s operating level has been increased to 94.1 per cent of the temporary full supply level.
This change took effect on 23 December 2021 and will allow for approximately 14,000 more megalitres to be stored in Callide Dam, should it receive further inflows this wet season.
In the instance of inflows and the storage reaching higher than 94.1 per cent, slow releases will be required to return the storage to the project operational level as soon as possible.
The FSL was required to temporarily change as, in the event of extreme weather events, 100 per cent capacity must represent when the water level reaches the top of the dam wall and is about to spill.
This recent change has not impacted the Callide Dam Emergency Action Plan and based on ‘fill and spill’ scenario mapping of historical Callide Dam data, between the months of December 2021 and May 2022, the probability of Callide Dam spilling remains low. We expect the temporary FSL will have little impact.
The table below explains the previous and current temporary full supply level of Callide Dam. The infographic on the Safety and emergency management page further explains this temporary change.
|Full supply level before project commencement||Temporary full supply level as of week commencing 21 June 2021||Temporary project operating level as at 23 December 2021|
|Capacity: 100% (top of|
|Capacity: 100% at top of spillway crest (was 41% with gates in place||Capacity: 94.1%|
|Volume: 136,300 ML||Volume: 55,382 ML||Volume: 52,098 ML|