We use Commonwealth water for the environment to help protect and restore the rivers, wetlands and floodplains of the Murray–Darling Basin.
In managing this water, we have 3 options:
- Use: Deliver water to a river, wetland or floodplain to meet an environmental demand.
- Carryover: Leave water in storage so it's available to meet environmental demands in the next water year.
- Trade: Sell or buy water for equal or greater environmental benefit.
Carryover gives entitlement holders flexibility to store water and use it when and where it is most needed.
What is carryover?
Sometimes, entitlement holders don’t use all of their water allocations within the water year. They save some for the next water year. This is called 'carryover'.
Entitlement holders can choose to carryover water, giving them more flexibility and predictability at the start of the new water year, when they don't know how much water they are going to have available to them. This is a common method used by entitlement holders.
Carryover is a critical tool for the CEWH.
In the southern Basin, rivers and wetlands would naturally receive water in winter and spring. Carryover ensures water is available at the start of the water year (that is, 1 July), to help meet these needs.
In the northern Basin, it helps us ensure water is available in future drier years.
Carryover rules
There are rules in place to make sure that carryover water doesn’t unfairly impact on other entitlement holders’ allocations. These rules are set by states and apply to all entitlement holders, including the Commonwealth.
This means no entitlement holder can fill up dams to the exclusion of other water users. Rainfall and inflows are more important in determining whether a dam spills or not, rather than the choices of an individual holder to carryover water.
How we make carryover decisions
We own over 60 different water entitlement types across the Basin and receive annual water allocations against them. Each licence will have different rules, including if carryover applies, and if it does, how much can be held until the next water year.
Carryover is an important consideration when deciding which accounts to leave water in or draw water from.
When deciding how much water to carryover, we aim to:
- avoid carryover in accounts that have enough water
- ensure there is enough water in accounts for needs early in a water year
- weigh the cost of water delivery and transfer fees against potential market costs
- consider the risk of carryover in accounts that might have trade restrictions the next year.
Other entitlement holders also consider these factors.
For information on current carryover volumes of Commonwealth environmental water, refer to Water holdings.
For more information, refer to the Usage and carryover summary 2012-21. This provides general use and carryover statistics for the Commonwealth Environmental Water Holder compared to other entitlement holders in the Basin.
Third party impacts
State rules don't allow entitlement holders to have significant third party impacts on others.
If we carryover more water than others, our accounts would fill more often and reach account limits. State rules would then reallocate water to other entitlement holders. Independent modelling confirms this.