Preparing for shortfall
How you can prepare for water shortages during high-demand periods.
A shortfall means that your allocated water is not available when and where you need it.
The MDBA regularly reviews forecast demands and climate and flows, and adjusts operations. For example, when water is released from from Lake Victoria and Menindee lakes and the Goulburn and Murrumbidgee rivers.
Irrigators and communities along the Murray River should be aware that there is an increasing risk of shortfall.
Shortfall risk for the Murray River
There has always been a risk that, during peak demand periods on the Murray River, water may not meet the demand downstream of the Barmah Choke. It takes about 3 weeks to deliver water from the Hume Dam to Sunraysia.
The Barmah Choke is a narrow section of the Murray River. It can pass a flow of around 9,200 ML a day downstream of Yarrawonga Weir, before water starts to pass into the Barmah-Millewa Forest.
The last shortfall was in 2002. Over the last 10 to 20 years there have been significant changes in both demand and supply across the connected Murray-Darling Basin. These changes have made it more challenging to deliver water to users without damaging the health of our waterways.
Types of shortfall
There are two types of shortfall related to water delivery in the lower Murray:
Delivery shortfall occurs when actual water use is higher than the need that was forecast. Needs are forecast when river water is released from Hume and Dartmouth storages. This happens weeks before delivery.
Delivery shortfalls are more likely to occur in an intense or extended heatwave. This is because a heatwave causes a sudden unexpected increase in demand.
System shortfall occurs when there is not enough capacity in the river and channel system to supply all downstream water needs. For example, when flows through Barmah Choke are already at full capacity. This means there is not enough water in the Menindee and Victoria lakes to meet all the lower Murray demands.
System shortfalls are more likely to occur towards the end of the irrigation season.
What happens when a shortfall occurs
When a shortfall occurs in the Murray, the MDBA confirms the volume available for diversion by Victoria. This volume is distributed to each affected water corporation, including Lower Murray Water.
We then ration the available water for distribution. This ration is based on demand and how many delivery or extraction shares are held in the shortfall areas.
As a result, delivery rights are based on sharing arrangements between water users. Delivery rights include delivery shares and extraction shares.
Shortfall may also result in temporary water restrictions. Restrictions are rare. However, they can happen when there are changes in climate, timing, location of demand, and land use – combined with the river system’s capacity to carry water.
How you can prepare for shortfall
Irrigation customers must place accurate orders for irrigation supply. When you do this, you must follow the rules for the system you operate in.
Improving delivery management
We work closely with the Victorian Government, the MDBA and other states to manage delivery challenges in the Murray River.
In Victoria the government assesses applications for new or increased extraction shares in the lower Murray to make sure they do not negatively impact existing entitlement holders or the environment.
In late 2021, new legislation was introduced to strengthen Victoria’s framework for delivery rights in a shortfall. This legislation also helps individual water users manage their shortfall risks.
In 2021–22, new Goulburn River trade and operating rules were introduced to make sure traded water can be delivered within ecological tolerances of the lower Goulburn, without increasing delivery risks in the Murray.
With the other states we are:
- informing water users about their delivery risks
- preparing coordinated response plans if water needs to be rationed in a shortfall
- monitoring new extractions
- assessing and reporting on any cumulative impacts to existing entitlement holders
- reviewing how we operate the system to minimise delivery risks.
For more information on what’s happening on the Murray River and what’s being done to manage the flow, see:
- Victorian Water Register – Murray River delivery risks and Goulburn to Murray trade rules
- MDBA – ‘River Murray Weekly’ report and Water demand (shortfalls)
- Department of Environment, Land, Water and Planning (DELWP)