Lake Hume is the major water storage on the Murray and Mitta Mitta Rivers and is just upstream of Albury-Wodonga. Releases from Hume Dam provides water downstream for irrigation, stock & domestic, urban consumption, hydroelectric power generation and environmental purposes. The Murray-Darling Basin Authority (MDBA) direct dam operations which are implemented under a joint arrangement with state agencies.
Following widespread bushfires in 2019-20, over 500,000 hectares was burnt in the upper Murray Catchment resulting in approximately 1,350, 000 tonnes of sediment being mobilised from the fire affected areas (Unpublished).
The impacts to water quality and dam operations due to the additional loads of sediment and nutrients entering Lake Hume, and the time this would take to manifest, was unpredictable.
During the summer Lake Hume typically becomes thermally stratified. This thermal stratification constrains water of poorer quality to the deeper sections of the dam where the primary release structures, are located on the dam wall.
During the summers of 2021 to 2024 inclusive, several water quality incidents had downstream ecological and urban consumption repercussions. The MDBA collaborated closely with downstream water users to devise mitigation strategies. Alternate operational methods were trialed to releases mitigate potential impacts.
The MDBA convened a workshop for water users within the region to discuss outcomes from the operational trials and how to adapt them to future operations. Currently during mid to late summer dam operations adaptively use these operational methods used as best practice.