Storage and sharing

State Storage shares

Under the Water Act 2007, the MDBA is required to carry out its functions in accordance with the Murray-Darling Basin Agreement which outlines how the waters of the River Murray system are shared between the states. An outline of how the MDBA manages the rivers is available here.

In simple terms, under the agreement NSW and Victoria equally share inflows into Dartmouth and Hume Dams and the Menindee Lakes storage system while retaining the full share of contributing tributary inflows in the state of origin. For example, Goulburn flows remain credited to Victoria while Murrumbidgee flows are retained by NSW. From the water held in storage and the inflows that are credited to each state, NSW and Victoria have to equally supply South Australia with entitlement flows which vary from month to month in accordance with the Agreement. In 2011, approval was given for South Australia to defer delivery of entitlement flows to store its share of water resources in MDBA storages where there is capacity to do so.

State sharing arrangements require that neither NSW nor Victoria can store more than 50 percent of the volume of the capacity of the storage. In the event a state exceeds half of the capacity, the excess water 'spills' into the account of the other state.

The MDBA updates the State Storage shares monthly and publishes these online here.

Water Sharing Plan

Allocations in the NSW Murray are made in accordance with the rules of the NSW Murray and Lower Darling Regulated Rivers Water Sharing Plan (WSP). The WSP outlines the hierarchy of allocating the NSW share of water held in the storages of the Murray-Darling Basin.

Water Sharing Plan

Supplementary water, formerly known as off-allocation water, is effectively surplus flow that is not needed to meet current demand and cannot be stored for future use. When these conditions exist, a period of Supplementary Access is announced. People with supplementary licences may only access water against these licences during periods of supplementary access. Those holding general security licences may access supplementary flows during these periods without debit to their general security accounts. More information about supplementary water is available here.

Under normal operating conditions, available water determinations (allocations) are made to access licences in the following order:

Supplementary Access


The WSP allows for General Security entitlement holders to carryover water from one season to the next to the value of 50 percent of the volume of their water entitlements.

Generally carryover water is accounted for before allocations are made against any other water access licence category.  A fact sheet about carryover can be accessed here.