Basin in Brief

From December to March severe rainfall deficiencies were experienced in the eastern corner of the northern Basin, according to the Bureau of Meteorology.

As shown in the graphic on the left, rainfall deciles for the same period were mostly below average or very much below average for most of the Basin, demonstrating the drier trend has already commenced.

Since late 2020, 3 La Niña events have helped increase the Murray–Darling Basin’s water storages, which are now sitting at 92% as of 8 March 2023.

February 2023 saw rainfall range from average to very much below average across the Basin. 

As shown in the graphic on the left, central areas of the of the northern and southern Basin received 0% of the monthly mean.

Despite this, water storages in both the southern and northern Murray–Darling Basin remain strong with whole of Basin storages at 92% as of 8 March 2023. 

In the northern Murray–Darling Basin rainfall ranged from average to very much below average. Towns like Mungindi in northern New South Wales received just 8.6mm for the month.

Meanwhile the southern Murray–Darling Basin was drier than average with towns like Corowa in Victoria recording high rainfall at 70mm for the month while Renmark in South Australia received just 2.2mm.

Public water storages across the Murray–Darling Basin declined slightly during February and were holding 20,573 GL (92%) as of 8 March 2023. This is very similar to this time last year on 16 March 2022 when whole of Basin storages were at 20,281 GL (91%).  

Public storages in the northern Basin decreased slightly from last month when they were at 97% on 1 February 2023.

The Menindee Lakes in far western New South Wales are still holding 100% capacity.

Other storages in the southern Basin have dropped slightly since last month, though they remain high at 15,103 GL (93%). This is a 5% drop from 1 February 2023 when southern Basin storages were sitting at 15,893 GL (98%). 

Despite this, storages are still high. As of 1 March 2023, Hume Dam was sitting at 96% while Dartmouth Dam was at 97%.

Traditionally, lower temperatures in autumn reduce the likelihood of water quality issues in the Basin as water temperature cools. The recent high flows have resulted in an increase of the risk of low dissolved oxygen across several areas in the southern Basin.

The Murray–Darling Basin Authority and state authorities monitor water quality across the Basin year-round. For more information on water quality and a map of threats, see the water quality page of our website.

Summary of key water quality issues

• Hypoxic blackwater: Current high flows and flooding is interacting with organic matter and carbon on the floodplains, increasing the risk of hypoxic blackwater events in the southern Basin.
• Low dissolved oxygen: In some systems, dissolved oxygen levels are falling due to flooding. At present these levels generally remain above critical ecological thresholds.
• Blue-green algae: : There is currently a low risk of blue-green algae, however conditions have the potential to change rapidly. For the latest information on blue-green algae alerts, contact the relevant state government contacts via the Getting information about current algal blooms page of our website.