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Highlights in this update

  • Much of the Murray–Darling Basin experienced average rainfall during October
  • Water storages in the Basin remain high with some dams at capacity
  • The Bureau of Meteorology’s ENSO status remains at La Niña ALERT
  • Spotlight story: Basin farmers to benefit from new climate tool
Rainfall percentages for 6 months to October 2021

Drought

Despite welcome rain across much of 2021 many areas of the Murray–Darling Basin are still experiencing the impacts of prolonged drought.

A negative Indian Ocean Dipole event during winter saw storges continue to fill, allowing whole of Basin storages to reach 90% as of 27 October 2021. Although this is positive news, the Bureau of Meteorology maintains that further periods of above average rainfall are needed to continue Basin-wide recovery, especially in parts of South Australia, Victoria, far west New South Wales, and southern Queensland.

The graphic to the left represents rainfall percentages for the Basin over the past 6 months. It demonstrates that while most of the Basin received 80 to 150% of average rainfall, some parts of the southern and northern Basin received as little as 40% during the same period. Rainfall deciles for the same period indicate that these areas experienced below average to average rainfall.

While conditions are improving thanks to rainfall, more is needed to fully lift the Basin out of drought. 

Rainfall deciles for October 2021

Rainfall

October saw a decline in rainfall with much of the Murray–Darling Basin receiving below average to average rainfall.

In contrast to September 2021, central parts of the Basin proved to be the driest with 5 to 10 mm of rainfall recorded. However, small pockets of the southern and northern Basin received above average rainfall, recording between 25 to 100 mm for the month.

Although rainfall decreased, whole of Basin storages remained high and as of 27 October 2021 were sitting at 90%.

Western catchments received 5 to 25 mm of rainfall during October, while falls in the eastern ranges were slightly better with catchments receiving 25 to 50 mm.

In the northern Basin, the New South Wales towns of Bourke (5.8 mm), Moree (23 mm), and Coonamble (33.4 mm) experienced average rainfall, while Walgett (20.4 mm) experienced low rainfall. On 12 October, Walgett recorded the lowest daily maximum temperature for New South Wales at 16.7 °C.

Meanwhile in the southern Basin, average rainfall totals were experienced in the New South Wales towns of Broken Hill (21.6 mm) and Wilcannia (16.2 mm), as well as the South Australian towns of Loxton (27.4 mm) and Renmark (9 mm). The Victorian towns of Bendigo (70.6 mm) and Yarrawonga (55.8 mm) in Victoria experienced high rainfall. The town of Wycheproof in Victoria also experienced its highest October rainfall total for at least 20 years, recording 64.6 mm.

Water storage levels across the Basin as at 27 October 2021

Water storages and streamflow

Public water storages across the Murray–Darling Basin continued to increase across October and were holding 20,036 GL (90%) as of 27 October 2021. This was an increase from 88% as of 29 September 2021.

Public storages in the northern Basin increased slightly and were holding 3,905 GL (83%). This was a 1% increase from 29 September 2021 when the northern Basin was holding 3,868 GL (82%).

Several public storages in the northern Basin were still at 100% capacity or more as of 27 October 2021. In the Border Rivers catchment, Pindari Lake was at 100% capacity. In the Macquarie catchment, Lake Burrendong was at 100%, while in the Namoi catchment, Lake Keepit was at 100% and Chaffey Dam was at 103%. With Chaffey dam exceeding 100% it is now above its capacity and surcharging.

Despite some northern Basin storages being at capacity several others were still under 50%. In the Namoi catchment, Split Rock Reservoir was at 47%, in the Macquarie catchment, Lake Windamere was at 37%, and in the Condamine-Balonne catchment, Cooby Creek Reservoir was at 15%.

Meanwhile, storages in the southern Basin have continued to steadily increase. As of 27 October 2021, southern Basin storages were holding 14,921 GL (92%). This is a 3% increase from 29 September when storages in the southern Basin were 14,426 GL (89%) and a significant increase from August 2021 when storages were 12,640 GL (78%).

Although rainfall across October ranged from mostly below average to average, storages like Hume Dam remained consistent. As of 27 October 2021, Hume Dam was sitting at 98%. Menindee Lakes was also sitting at 112% capacity as of this date.

According to the Bureau of Meteorology’s drought statement, Hume Dam water storage is at its highest level in nearly 5 years while Menindee Lakes water storage is at its highest level in almost 9 years. Water is now making its way from Menindee Lakes down the Great Darling Anabranch for the first time since 2017.

Climate outlook – The Bureau of Meteorology’s ENSO status remains at La Niña ALERT

The Murray–Darling Basin is likely to experience a wet end to 2021 thanks to the increased likelihood of La Niña developing.

The Bureau of Meteorology’s El Niño–Southern Oscillation (ENSO) Outlook is at La Niña ALERT. In the past when La Niña ALERT criteria have been met, La Niña has subsequently developed 70% of the time; this is around triple the normal likelihood. A La Niña event will increase the chances of above average rainfall for the Basin during spring and summer.

The negative Indian Ocean Dipole (IOD) event is expected to weaken and return to neutral in November.

As a result, November 2021 to January 2022 is likely to be wetter than average for the Basin. Daytime temperatures across November to January are likely to be warmer than average for western catchments, while night-time temperatures are expected to be warmer than average across the entire Basin.

Near median to high stream flows are also expected, with further rainfall likely to increase the risk of flooding in the southern Basin.

Threats to water quality in the Murray-Darling Basin - November 2021

Water quality

Water quality issues continue to be assessed, with an overall lower risk in line with seasonal expectations.

The MDBA and state authorities continue to monitor water quality across the Basin. 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

  • Blue-green algae: Many locations throughout the Basin are at risk of algal blooms. 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.
  • Bushfire contamination remains a possible threat in the upper Murrumbidgee, upper Murray and Ovens catchments following rainfall. This risk will reduce as areas recover from bushfire damage.

Spotlight: Basin farmers to benefit from new climate tool

The new features use the latest climate science and technology and have been tried and tested by farmers across the dairy, meat, grain, sugar and wine sectors. Farmers have found the tools helpful in anticipating climate conditions and building climate resistance. 

This new tool is part of the Forewarned is Forearmed project, a partnership between government, research and industry sectors, funded through the Rural R&D for Profit program

The new outlook maps and features can be viewed through the Bureau of Meteorology by selecting the ‘Chance of extremes’ button on the left-hand side.

Additional climate outlook information will pop up when you enter your town name using the search option, or when you click on your location on the map.

For more information on the Forewarned is Forearmed project see: