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.
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
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.