Sustainable Diversion Limit Adjustment Mechanism

The Basin Plan is a flexible and adaptive plan that balances the needs of Basin communities and the environment, to achieve a healthy and productive river system. Under the Basin Plan, there are a range of opportunities to optimise environmental outcomes.

The Basin Plan

View a short video that explains the Basin Plan.

The Basin Plan sets Sustainable Diversion Limits, which is how much water can be used in the Murray–Darling Basin, while leaving enough water for the environment.

To provide flexibility, the Basin Plan includes a mechanism to adjust Sustainable Diversion Limits. If Basin Plan environmental outcomes can be reached with less water, more water can remain in the system for other users, including irrigated agriculture. Similarly, if farming practices can be made more efficient, more water can be made available for the environment.

Improvements can be made to save water through water supply infrastructure, changes to river operating rules and improvements in water use efficiency. These changes can benefit the environment by using water more effectively to achieve the outcomes of the Basin Plan. 

Basin governments have identified a suite of projects which make the delivery of water more efficient and flexible. An assessment by the Murray–Darling Basin Authority (MDBA) has determined there will be 605 gigalitres (GL) additional water available for communities through the Adjustment Mechanism, if the package of projects is agreed.

Basin governments are also evaluating ways in which up to 450 gigalitres (GL) may be secured for the environment through programs that improve the efficiency of water use between now and 2024.

The Sustainable Diversion Limit Adjustment Mechanism

View a short video on what it is and how it works.

Supply Measures

Supply projects are new ways to manage the Basin's rivers to more efficiently deliver water for Basin Plan environmental outcomes, allowing more water for consumptive use.

Projects include environmental works, such as building or improving river or water management structures and changes to river operating rules, which achieve environmental outcomes, with less water.

Community input is critical to the ongoing detailed design and implementation of these projects.

Basin governments will work in partnership to provide information to communities about how they can contribute.

Efficiency projects

Efficiency projects provide more water for the environment by making water delivery systems more effective and efficient.

This can include replacing or upgrading on-farm irrigation, or lining channels to reduce water losses within an irrigation network.

These projects need to have no adverse socio-economic impacts on Basin communities and industries.

Governments have commissioned EY to conduct an Efficiency Measures Review of how to best design, target and resource efficiency measures to provide additional water for the environment.

Constraints measures

Constraints projects aim to overcome some of the physical barriers that impact delivering water in the system. Constraints projects can include changes to physical features such as crossings and bridges. They can also change river operating practices and rules. They could allow water managers more flexibility in releasing and moving water through the system.

A constraints project, for example, could offer a better way of managing dams. The potential water releases are typically below minor flood level onto low-lying (or slightly higher elevation) floodplains, fairly close to the river channels.

No changes to flows will occur until all third party impacts have been resolved in consultation with affected communities. Find out more about constraints.

How the adjustment to Sustainable Diversion Limits is determined

In consultation with Basin governments, the MDBA has developed an assessment framework, to assess how much water is being saved through the Sustainable Diversion Limit Adjustment Mechanism supply projects. This assessment framework has been used to calculate the new Sustainable Diversion Limit.

The framework is complex and includes components such as computer (hydrological) models, hydrological indicator sites, limits on hydrological change and ecological equivalence scoring.

This framework has been trialled and thoroughly reviewed by independent experts and all Basin governments. It is scientifically rigorous and suitable for determining an appropriate adjustment.

The framework compares project outcomes with the Basin Plan and applies tests during the comparison to ensure the outcomes of the Basin Plan are achieved.

Sustainable Diversion Limit Adjustment Mechanism timing

timeline of sustainable diversion limit implementation from 2017 onwards

Roles and responsibilities

The MDBA has assessed the projects, calculating and proposing the Sustainable Diversion Limit Adjustment Mechanism assessment.

The Sustainable Diversion Limit Adjustment Mechanism assessment (draft determination) was available for public comment from 3 October–3 November 2017.

Basin governments are aware of a range of issues and opportunities and plan to incorporate these into implementation activities over the coming years.

Basin state governments are responsible for delivering the projects at a local-level, including consulting with communities and detailed project design and implementation.  

The MDBA will monitor the integrity of the Sustainable Diversion Limit Adjustment Mechanism in delivering the Basin Plan's environmental outcomes by regularly reporting progress in implementation.

Projects are funded by the Australian Government.