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Highlights in this update

  • Significant flooding is affecting several catchments

  • Dam levels currently the highest in more than 10 years

  • Water quality threats increased in the southern Basin

  • Spotlight – how we run the River Murray System

     

Rainfall percentages, 48 months to October 2022 (detail in page content)

Drought

La Niña conditions are continuing to alleviate drought conditions across the Basin, with record-breaking rainfall experienced in many catchments over the past months. Soil moisture levels for October were very much above average, according to the Bureau of Meteorology.

Looking at longer-term trends, the 4-year rainfall percentages in the map to the left show that while the majority of the Basin received 100% of average rainfall, northern and south-western areas recorded as little as 40% of average.

Over the same time period, a region straddling the Lachlan and Macquarie catchments received 125% of average rainfall.

Rainfall totals for October 2022 (Detail in page text)

Rainfall

October brought an increase in rainfall over preceding months – an average of between 25 and 400 mm fell across the Basin. Many areas of Victoria and New South Wales were highest on record.

Highest falls were recorded in the southern ranges, specifically the alpine region of Victoria where 490 mm was recorded at Mount Buller in Victoria. This rain created high flows in the Ovens and Goulburn-Broken catchments, resulting in localised flooding.

Further north and west were pockets of rainfall up to 300 mm in the Namoi and Darling catchments.

Coonamble received the least rainfall, with 21.6 mm.

Water in storages as at 9 November 2022

Water storages and streamflow

Basin water storage levels continued to increase during October, with levels the highest seen in over a decade.

Many dams throughout the Basin are currently spilling as a result of high inflows and management practices to maintain airspace, where possible, while minimising flooding.

All weirs downstream of Yarrawonga on the Murray River have been removed, allowing free flowing conditions to the Lower Lakes in South Australia. As at 9 November the flow to South Australia was over 90,000 megalitres per day, however this is changing based on prevailing upstream conditions.

Several flood watches and warnings have been issued by the Bureau of Meteorology, and with above average rainfall expected over the coming months the risk of flooding remains high, and repeat events may occur in some catchments. Please refer to the Bureau’s national warnings system, Rainfall and River Conditions for up-to-date information on riverine conditions and flood levels.

The Bureau is responsible for forecasting river heights during flood events and the Murray–Darling Basin Authority does not provide forecasts for locations where flooding is occurring.

Climate and water forecast - November to January

The Bureau of Meteorology are forecasting that La Niña will remain in effect for the coming months, and the long-range forecast indicates higher than average rainfall for most of eastern Australia – including the Murray–Darling Basin.

Saturated soils, full rivers and dams and expected rain will increase the risk of further flooding in the Basin.

Threats to water quality for November 2022

Water quality

The likelihood of water quality issues has increased as high flows move through catchments, and floodwaters bring nutrient loads into river systems. Several rivers in the southern Basin are at high risk of blackwater and/or low dissolved oxygen.

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.

Spotlight: How we run the River Murray System

Image: Aerial view of Yarrawonga Weir on the Murray River.


The Murray–Darling Basin Authority (MDBA) takes a Basin-wide, collaborative approach to managing water to achieve a healthy and productive river system.  
 
Managing water in the Basin is a partnership between state governments and the Commonwealth. There are different arrangements in place for operating dams and infrastructure across the Murray–Darling Basin. The MDBA operates some water infrastructure in the River Murray system in the southern Basin. State governments are responsible for water infrastructure across the rest of the Murray–Darling Basin. This infrastructure includes weirs, locks, dams and levees.  

Dams are constructed, maintained and operated to capture and store water, allowing flows to be regulated for irrigation, water supply to downstream communities and to provide water for the environment. In some instances, dam storages provide an opportunity to mitigate floods, depending on how much water can be captured. 

Water across the southern-connected Basin is managed, meaning flows in the River Murray are controlled to ensure water is stored and delivered when and where it’s needed.

The MDBA directs infrastructure operations at several key locations, including:

Dartmouth Dam   

- Hume Dam 

- Yarrawonga Weir 

- Torrumbarry Weir  

- Lake Victoria     

- Lock 26 Torrumbarry Weir and locks and weirs from Lock 15 at Euston to Lock 7 at Rufus River 

- Regulators and pumpstations delivering water for the environment onto floodplains. 

Other important operational roles of the MDBA are: 

- sharing water in the River Murray between New South Wales, South Australia and Victoria 

- management of salt interception schemes 

- overseeing maintenance of existing assets and construction of new assets.