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SA deferred water storage and delivery plan

Under clause 91 and Schedule G of the Murray-Darling Basin Agreement 2008 (the Agreement), South Australia can defer and store part of its annual Entitlement in River Murray storages, such as Dartmouth and Hume Dams and Lake Victoria to meet critical human water needs and/or private carryover in dry years. This is known as South Australia’s Storage Right, which is an important element of South Australia’s water security framework.

Critical human water needs are considered the highest priority water use and the water sharing arrangements between Basin states ensure that the delivery of water for critical human water needs is prioritised. The Water Act 2007, Basin Plan 2012 and the Agreement include obligations for critical human water needs, which recognise the importance of having arrangements in place for periods when there is low water availability.

The Basin Plan sets out the volumes of water required to meet critical human water needs of communities that are dependent on the waters of the River Murray, and each Basin state is responsible for meeting its own critical human water needs. The Basin Plan states that South Australia’s critical human water needs requirements from the River Murray are 204 gigalitres (GL) per year. This volume comprises 150 GL for Metropolitan Adelaide and associated country areas, 34 GL for country towns and a further 20 GL for licensed and unlicensed stock, domestic, industrial and dairy requirements not provided for by reticulated supply.

Deferral for critical human water needs

South Australia is responsible for meeting its own critical human water needs requirements either from the current year’s available Entitlement and/or from water deferred and stored in previous years. In accordance with the South Australian River Murray Water Resource Plan, South Australia will aim to have in storage up to an equivalent of 150 percent (306 GL) of its annual critical human water needs, ahead of any year where it is expected that the full Entitlement volume of 1,850 GL will not be available. However, South Australia will not defer more than 100 percent (204 GL) of its annual critical human water needs in any 12 month period. 

During a sequence of dry years, the volume of water held in the Storage Right for critical human water needs should be maintained at a minimum of 131 GL (as far as practicable).  This ‘dry year reserve’ ensures that without any water available in South Australia’s Consumptive Entitlement, critical human water needs requirements may be met through a combination of water held in storage and water provided from the Adelaide Desalination Plant.  This is a critical element of the policy settings in South Australia in meeting critical human water needs from the Storage Right if it is required.

Under the Water Allocation Plan for the River Murray Prescribed Watercourse, when allocations against Class 3 (High Security) entitlements are less than 100 percent, SA Water can only take up to 100 GL for Metropolitan Adelaide from South Australia’s Consumptive Entitlement. In these years, additional requirements up to Metropolitan Adelaide’s annual maximum critical human water needs requirements of 150 GL must be met from other sources.  This includes from water held in the Storage Right, subject to maintaining the dry year reserve of 131 GL.

More information on South Australia’s deferral for critical human water needs can be found in the South Australian River Murray Water Resource Plan and the Methods Document for the Implementation of the Sustainable Diversion Limit for the South Australian Murray SDL Resource Unit (SS11).

Deferral for private carryover

For private carryover purposes, South Australia aims to have in storage up to a maximum of 20 percent of the volume held by eligible water access entitlement holders, ahead of any year in which private carryover is to be provided.

Deferred Water Storage and Delivery Plans

Under the Agreement, South Australia is required to provide the Murray-Darling Basin Authority (MDBA), New South Wales and Victoria by the first day of each month, a draft Deferred Water Storage and Delivery Plan (the Plan) for at least the following 12 months. The Plan takes into account the best available information at the time of preparation and is subject to change throughout the water year as updated water availability information becomes available.

In addition to providing a copy of the Plan to the MDBA, New South Wales and Victoria, a copy of the approved Deferred Water Storage and Delivery Plan is also provided to the Commonwealth Environmental Water Holder.  The Commonwealth Environmental Water Holder is also consulted regularly, but no less than once every twelve months, on the development of the Deferred Water Storage and Delivery Plan.

South Australia’s deferral schedule for at least the following 12-months is published below (Figure 1) and will be updated following notification from the MDBA indicating that the Plan has been accepted.

   Critical Human Water Needs
(GL)
Private Carryover
(GL)
 
 Preferred Storage
 Oct-20  0.0  0.0  Dartmouth
 Nov-20  0.0  0.0
 Dec-20  0.0  0.0
 Jan-21  0.0  0.0
 Feb-21 0.0  0.0
 Mar-21 23.0  0.0
 Apr-21 17.5  0.0
 May-21 9.5  0.0
 Jun-21 0.0  0.0
 Jul-21  0.0  0.0
 Aug-21 0.0 0.0
 Sep-21 0.0  0.0
 Total  50.0  0.0

Figure 1: Deferral Schdule – October 2020 to September 2021*

*The volumes for deferral in Figure 1 assume a South Australian Entitlement Flow of 1,850 GL in 2020‑21.
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