Murray–Darling Basin History

The Murray–Darling Basin is of significant environmental, cultural and economic value to Australia. Discover more about the history of the Basin including the Murray-Darling Basin Authority and Basin Plan, which ensures we have a healthier, working Basin that takes into account the needs of people and the environment.

The Murray–Darling Basin Agreement

In 1915, the Commonwealth, Victoria, New South Wales and South Australia, made arrangements to build up and share the Murray River's water. Two years later they formed the Murray River Commission to shepherd their goals.

They set forth that Victoria and New South Wales would each receive 50 per cent of flow from Albury (such as inflows to Hume, Dartmouth and Kiewa) and 50 per cent of inflow from Menindee Lakes. Other inflows to the river are credited to the state from which they originate, such as flow in the Goulburn River at McCoys Bridge is credited to Victoria and the Murrumbidgee River at Balranald to New South Wales. South Australia owns all Murray River water within its state borders.

During dry periods, special accounting rules apply to ensure the available water is shared equally between the states. Water needed to keep the river running, including that which is lost to evaporation, seepage (called conveyance water) and a reserve for the following year are set aside before water allocations to each state is made. Victoria and New South Wales equally supply conveyance water and South Australia’s entitlement flows as defined in the agreement. The Commission eventually became the Murray-Darling Basin Authority, which does not own any water and is responsible for managing the river's water in accordance with the agreement.

Since 2009, the water sharing agreement has operated as Schedule 1 under the Commonwealth Water Act. Murray–Darling Basin Ministerial Council can change the agreement with consent from all parties.

The Murray–Darling Basin Plan

The Murray–Darling Basin Plan was signed into law on 22 November 2012, after the Commonwealth reached an accord with each of the Basin states. The plan is separate from and does not change the water sharing arrangements in the Murray–Darling Basin Agreement.

The plan aims to address environmental degradation resulting from historic water over-allocation for irrigation and other uses. The plan articulates high-level policy objectives for the Basin's water resources, including the introduction of new legally enforceable overall limits on water extraction, called the Sustainable Diversion Limit (SDL). SDLs are set at Basin-wide, catchment and aquifer scales. The Authority has estimated the Basin-wide SDL for surface water is 10,945 gigalitres per year (GL/y). At the catchment scale, SDLs are implemented through Basin states’ water resource plans.

River users have historically extracted more water than is now allowed under the SDL. The plan sets a target to recover 2,750GL of water from consumptive use to comply with the SDL set by the plan. Measures to recover this water include direct buy-backs of water from irrigators, supply projects aiming to achieve equivalent environmental outcomes with less water, efficiency projects aiming to change water use and save some for the environment, and constraints projects aiming to overcome physical barriers to deliver, including physical features, operating practices or rules. Any water savings are transferred to the environment.

Water recovery in the Basin

In January 2018, amendments were made to The Murray–Darling Basin Plan, which reduced the Basin-wide water recovery target (the SDL) by 605GL. The plan’s target for water recovery was reduced to 2,075 GL/y, but a target of up to an additional 450 GL/y of water recovery for enhanced environmental outcomes – subject to neutral or positive socioeconomic outcomes – was adopted. The accounting is set out in Table 1. Water recovery is to be achieved by 2024, although the Productivity Commission doubts this target is achievable.

Table 1: Summary of the Water Accounting

Sustainable Diversion Limit Adjustment Mechanism

The Murray–Darling Basin Authority has assessed and agreed to implement 39 SDL supply, efficiency and constraints projects that achieve equivalent environmental outcomes with less water. The authority assessed the projects using the Sustainable Diversion Limit Adjustment Mechanism and determined that when these projects were implemented, the environmental outcomes of the Murray–Darling Basin Plan can be met with 2,145GL of water recovery rather than 2,750GL, a reduction of 605GL.

SDL offset projects include works to enable wetlands to be watered and constraints projects to enable river operators to run the rivers above bank full, but below minor flood level, to deliver environmental flows and water to low-lying areas of the floodplain. Some private land would be inundated.

Enhanced environmental outcomes

The Murray–Darling Basin Plan allows for a Commonwealth program for enhanced environmental outcomes, over and above what is to be achieved by the original target of 2,750GL, by recovering an additional 450GL per year of environmental water above the 2,750GL target.

The efficiency projects to recover this additional water must have a neural or positive socioeconomic impact. The Murray–Darling Basin Ministerial Council agreed to the criteria to determine if proposed projects have a neutral or positive socioeconomic impacts in 2018. The recovery of the additional 450GL for enhanced environmental outcomes is controversial as it was a late addition to the original legislation and it involves taking further water from the consumptive pool. Progress on recovering water under the various components of the plan can be tracked through the Murray–Darling Basin Authority.