Murray-Darling Basin Water Management

The Murray-Darling Basin (MDB) is the most productive but also the most exploited water system in Australia. In ‘normal’ years, about 95 per cent of the Basin’s water resources are committed for irrigated agriculture. The present drought has exacerbated the impact of the existing over-allocation of water from the rivers. The resulting water deficit has affected the ecological health of the rivers. On top of that, expert estimates suggest that the water yield of the MDB could decline by 1100 Gigalitres (GL) per year over the next 20 years due to climate change.

Over-allocation of water has been an issue in the MDB for some time and there have been several attempts to address this issue. The Cap on diversions set in 1995 was supposed to prevent more allocation, but a review of the Cap found that there was no certainty that its current level represented a sustainable level of diversions. The 2004 National Water Initiative (NWI) and associated MDB intergovernmental agreement was the next attempt to deal with the issue.

The diversion of water for irrigation has significantly reduced ‘environmental flows’ in the MDB. An environmental flow refers to water that is released to maintain the natural ecology of a river and its associated tributaries and wetlands. The first step of the Living Murray initiative committed 500 GL to improve flows in six iconic sites on the Murray. So far, no environmental flows have been returned to the Murray, although projects under the initiative totalling 285 GL are being implemented. However, there are scientific estimates that at least 1500 GL of additional environmental flows are needed to restore the health of the Murray. The Australian Labor Party (ALP) has committed to returning 1500 GL in environmental flows to the MDB system.

By January 2007, the NWI and Living Murray had yet to meet their aims. At the time, then Prime Minister John Howard noted that the current trajectory of water use and management in Australia was not sustainable and that the average annual flows in the MDB would decline by 15 per cent by 2020. He announced the $10 billion National Water Plan to improve water efficiency and address over-allocation in the MDB. Up to 30 per cent of MDB irrigation water may be lost during transportation, because of leakage, seepage and evaporation.

At the centre of the water plan is the Commonwealth takeover of water management in the MDB. The Water Act 2007 established the MDB Authority to manage water resources in the MDB using only Commonwealth Constitutional powers rather than referred state powers. Victoria has yet to agree to refer its powers over water management to the Commonwealth, unlike New South Wales, Queensland, South Australia and the Australian Capital Territory. While the ALP supported the Commonwealth takeover of MDB management, it is committed to negotiating a new arrangement to include Victoria.

The ten-year National Plan for Water Security allocates $6 billion to modernise irrigated agriculture and $3 billion to address over-allocation in the MDB. It is expected that about 2500GL would be saved by modernising irrigation in the MDB with half going into environmental flows and half returned for use by irrigators.

Over-allocation will be remedied by giving financial support to help relocate non-viable or inefficient irrigators (or to help them exit the industry), and also by the purchase of existing water entitlements. CSIRO is determining the extent of over-allocation in the MDB, and that information will be used to develop a new cap on extractions in the MDB.

The Howard Government ruled out the compulsory acquisition of water entitlements as a means to bring water allocations throughout the MDB to a sustainable level. Under the provisions of the Water Act, the Commonwealth Government can only purchase such entitlements on the open market. However, the ALP’s stance on this policy suggests that it may consider the compulsory buyback of water entitlements.

Commenting on the National Plan for Water Security, National Water Commission commissioner Professor Peter Cullen stated that, because of the possible halving in available water in the MDB in the future through events such as climate change, ‘we will get a reduction in perennial crops and an increase in opportunistic annual crops’. He urged the federal government to buy entitlements before investing in infrastructure, noting that, if it did not, infrastructure upgrading could occur in the wrong places.

The Australian Conservation Foundation has called for expenditure on the MDB to be fast-tracked. It claims that over the next three years the plan ‘would deliver next to nothing—at best 200 gigalitres (GL)—while science is telling us the river system needs at least 1500 GL just to have a moderate chance of survival’.

Although the thrust of the water plan has general support, there are still issues of concern to some groups. Recent proposals to auction additional water allocations in two Queensland Rivers, the Warrego and the Paroo, have raised concerns about the effects on users and on the environment in downstream states. The Commonwealth Government opposed the Queensland Government’s proposal for a September 2007 auction of 8 GL of water entitlements in the previously unallocated Warrego River, and Queensland Premier Anna Bligh decided to put the proposed sale on hold indefinitely. In November 2007, two federal Nationals MPs called for the sale of Paroo water entitlements to landholders and disagreed with cancelling the sale of Warrego water entitlements.

Documentation
Department of the Environment and Water Resources, ‘The Water Act 2007’, web resource, 2007.
Department of the Environment and Water Resources, ‘National Plan for Water Security’, web resource, 2007.
National Water Commission, ‘Australian Water Resources 2005’, web resource, 2007.