The Murray-Darling Basin Plan was developed as a requirement of the Commonwealth Water Act 2007. The Basin Plan determines the amount of water that can be extracted annually from the Murray-Darling Basin for consumptive uses, including urban, industrial, and agricultural uses. This volume is called the Sustainable Diversion Limit, and represents a volume that can be used while ensuring the environmental outcomes and functions of the rivers, waterways, groundwater, and wetlands of the Basin.
The Murray-Darling Basin Authority (MDBA) determined that the average baseline diversion level for surface water in the Basin in 2009, prior to the implementation of the Basin Plan, was 13,623 GL. Based on scientific research, ecological modelling, and social and economic studies, the MDBA has determined that the long term Sustainable Diversion Limit (SDL) for surface water is approximately 10,873 GL per year, or 2,750 GL lower than the 2009 baseline. This difference was recommended to be bridged by a combination of SDL adjustment projects and water recovery, including licence buybacks and infrastructure projects. More information about Sustainable Diversion Limit Adjustments.
Under the Basin Plan, there is an SDL for the Basin as a whole, with additional SDLs applicable to individual valleys and catchments. To meet the SDLs, water will be managed through Water Resource Plans (WRPs), which will replace the existing NSW Water Sharing Plans under which water is currently managed. WRPs will set out the rules and arrangements under which water is managed, including annual limits on water take, the delivery of environmental water, management during extreme events, and strategies to achieve water quality standards. WRPs are currently under development with input from Stakeholder Advisory Panels.
Supply and efficiency measures
The Basin Plan states that up to 650 GL of the water to be recovered can be offset through Supply measures, or works to achieve equivalent environmental outcomes with less water. The Basin Plan also provides for the recovery of up to an additional 450 GL for the environment through efficiency measures funded by the Commonwealth, provided they have a neutral or positive socio-economic impact. More information about Supply and Efficiency measures.
Under the Basin Plan, the MDBA has also developed a strategy to manage constraints, where a constraint is any rule or structure which limits the volume and timing of environmental water delivery within the Basin. Constraints include physical structures, river management practices, and river height operational limits.
While easing constraints will not independently lead to the recovery of more water, work completed by the MDBA has shown that it will allow better outcomes to be achieved through the use of environmental water. More information about constraints measures and specific projects.
In 2016, the water ministers agreed to consider implementing a range of complementary projects intended to contribute to the triple bottom line outcomes under the Basin Plan.
Complementary measures are projects that do not provide water offsets or an offset volume, but which help to provide improved environmental outcomes through a range of other interventions. These include management activities such as:
- The installation of fishways and fish diversion screens
- Carp management activities including release of the carp herpes virus
- Investments and infrastructure to manage cold water pollution, and
- Habitat restoration and riparian management activities.
These projects are intended to be part of an integrated approach to addressing environmental issues, and seek to provide a ‘more than water’ approach to environmental management. Complementary measures projects remain at the conceptual stage, and funding for them has not yet been made available.
In 2017, the MDBA commissioned the CSIRO to assess the relative benefits of complementary measures. Their findings are available on the MDBA website.
Relevant policies and reports
A range of policies and measures are required to be in place to underpin the SDL projects and ensure they can provide maximum benefits to the environment. These policies are aimed at maximising the benefits of the delivery of environmental water, as well as helping to track and account for water recovery towards the SDL.
Also included in this section are reviews and reports on the implementation and effects of the Basin Plan.
- Analysis of efficiency measures in the Murray-Darling Basin – the Ministerial Council commissioned Ernst and Young to complete an analysis of the proposed efficiency measures, and if and how they could be implemented in a socio-economically neutral manner.
- Murray-Darling Basin SDL adjustment mechanism: Report by the Victorian and NSW Ministers’ Independent expert panel ((PDF 890.5 KB)) – An Independent Expert Panel was asked by the Victorian and NSW governments to complete a review of the SDL adjustment mechanism, focusing on the application of the mechanism, key assumptions, interpretations, and anticipated environmental outcomes.
- Pre-requisite policy measures implementation plan ((PDF 163.1 KB)) – Pre-requisite policy measures are policy measures that the original modelling of the Basin Plan assumed to be in place to allow the efficient delivery of environmental water. In the absence of pre-requisite policy measures, larger quantities of environmental water would need to be recovered to achieve the same results.
- Northern Basin review: NSW synopsis ((PDF 57.1 KB)) – The Basin Plan was based on the best science available at the time. However, because of greater uncertainty in the data available for the Northern Basin, a later review of its water recovery target was undertaken. The review ultimately recommended that the Northern Basin target be reduced. Note: the legislative instrument that gave effect to the recommendations of this review was disallowed by the Australian Senate on 14 February 2018.
- NSW submission on proposed Basin Plan Amendments ((PDF 164.1 KB)) – the MDBA proposed amendments to the Basin Plan in November 2016, including changes to groundwater management and to targets for the Northern Basin. NSW supported the proposed amendments with minor changes.