Water availability is dependant on climate

The amount of water available for consumptive use will vary from year to year.

While a user may have an entitlement, this  does not necessarily mean that they will receive a full seasonal allocation.

What mechanisms are used to respond to changing water availability?

An important aspect of the allocation framework are the various mechanisms to manage both seasonal variability and to respond to periods of water shortage. These include:

• seasonal allocations – water shares in effect specify a maximum amount of water that can be taken. In each year in a regulated system, a decision will be made about how much water is available to the holder of these entitlements. This may change during the season.
  
• urban water restrictions – water authorities have the ability to make rules to restrict urban water use in times of shortage.
• rosters, restrictions and bans – they apply in unregulated surface water systems and groundwater systems to limit the time or amount of water that can be taken.

Capping and limits ensure water use is managed

The Water Act 1989 provides a number of mechanisms to cap the total amount of water that can be taken out of a particular water system. Interstate agreements also limit the amount of water that can be taken. 

• Permissible Consumptive Volume (PCV) - The Minister for Water may limit the total volume of water, whether surface water or groundwater, that can be taken in a particular area or water system for a specified period by declaring a PCV by Order published in the Victoria Government Gazette (section 22A).
• Management Plans - Management plans for water supply protection areas may restrict or prohibit the issue licences to take and use either groundwater or surface water. Management plans may also restrict the taking of water to ensure that flows in waterways or groundwater levels are maintained.
• Border Groundwaters Agreement - Under the Groundwater (Border Agreement) Act 1985 Victoria and South Australia have limits placed on the amount of groundwater that can be allocated in a 40-kilometre designated area centred on the border between the two states. The designated area is divided into 22 zones and permissible annual volumes have been specified for these zones.
• Murray Darling Basin Agreement - under this agreement established through the Murray Darling Basin Act 1993, a cap is placed on the amount of water that can be used in the basin and has the effect of preventing additional water from being allocated.

The Minister for Water may qualify rights

In extreme circumstances, for example a drought, or long term change in water availability, the Water Act 1989 provides that entitlements to water may be qualified by the Minister for Water.

A temporary qualification changes a legal entitlement to water and may be made in response to seasonal water shortages where there is insufficient water to meet the needs of water users at any particular time.

A permanent qualification of rights may be considered by the Minister for Water after 2021 but can only be made following a long term water resource assessment (section 22K-T). 

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