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Published: 28 October 2019   •   Media statements

The MDBA provided the following statement to Channel 9 60 Minutes on 16 October 2019 in response to questions raised ahead of the program airing on Sunday 27 October 2019.

The MDBA offered an on-camera interview with the program, which they declined.

The Murray–Darling Basin Authority operates the River Murray on behalf of New South Wales, Victoria and South Australia. These arrangements have been in place for over one hundred years.

At all times, the MDBA operates the River Murray according to the rules of the Murray-Darling Basin Agreement. The Agreement lays out the way water is shared between the states, and how the MDBA delivers their water.

Entitlements to water are held by farmers and environmental water holders—they can choose to use their allocated water according to their needs. The MDBA has no role in this process.

A healthy and sustainable river system benefits everyone.

Overview

  • The Murray–Darling Basin Authority operates the River Murray on behalf of and in conjunction with Basin state governments, including New South Wales, Victoria and South Australia.
  • The arrangements for management of the River Murray are contained in the Murray–Darling Basin Agreement. The Agreement outlines the MDBA's role in managing the system, it establishes the key governance frameworks, arrangements for the sharing of water between the states, and the requirements for operating the system’s built assets.
  • The MDBA's consultative and expertise based approach is central to maintaining the confidence of Basin states and consensus on management of these shared resources. 
  • The MDBA's decisions are made in consultation with Basin states and proceed on the back of detailed and ongoing discussions, including those with the Water Liaison Working Group (WLWG) (a group of state and commonwealth officials) and environmental water holders.
  • The MDBA is confident that it operates the River Murray system consistent with the Agreement and operational arrangements based on the best available information. The MDBA runs the River Murray system efficiently and effectively in order to deliver state water entitlements.
  • Operating the River Murray is a complex task. It requires expert judgement. River operators must consider and balance a range of factors—the weather and climate conditions, modelling and forecasting, anticipated demands and delivery needs, and operational limitations and constraints. River operators respond to evolving conditions, and operational strategies are adapted based on emerging conditions and issues. The MDBA stands behind this work.

MDBA role in river management

  • The MDBA determines the volume of water released to meet demands, but does not own any water. The MDBA can only release water from storage to meet state orders or system demands.
  • The MDBA determines how much of the available water in the River Murray system belongs to each state, through monitoring water storage levels and inflows into the river.
  • Water allocations, water orders and the delivery of water work in a different way from state to state and will continue to do so. The MDBA is not involved in making allocations to individual entitlement holders, as this is managed by state governments.

Barmah Choke

  • The Barmah Choke is a narrow section of the Murray River that runs through the Barmah-Millewa Forest. The Choke is made up of three key flow constriction points: the Tocumwal Choke, the Barmah Choke and the Edward Choke.
  • The Choke restricts the flow of the Murray River to around 7,000 megalitres (ML) per day, estimated at Picnic Point. The Choke has a trade restriction to protect delivery to existing entitlement holders and to maintain the river environment in the Choke.
  • River operators need to consider the limitations of using the Choke to deliver water downstream, and balance this with the environmental risks for the forest and river.

Barmah Millewa forest

Hume Dam releases and Losses in the River Murray System 2018-2019

  • The MDBA report Losses in the River Murray System 2018-2019 (the Losses Report) provides an overview of the factors that influenced river operations and conveyance losses occurring along the River Murray from Hume Dam through to the South Australian border in the 2018-2019 period. The full report is available at: https://www.mdba.gov.au/publications/mdba-reports/conveyance-losses-river-murray-system
  • Below average rainfall meant that Lake Victoria did not rise as it typically does. Without sufficient water in Lake Victoria, there was a very high risk that state water entitlements could not be met. Accordingly, additional water above channel capacity was transferred from Hume Dam commencing from September 2018. These transfers were undertaken with agreement from the states. 
  • An excerpt from the Losses Report discusses this in the following terms:
    • In the 2018–19 year the ability to minimise losses was restricted by the warm, dry conditions, low tributary inflows and high demands. As Lake Victoria’s storage did not start to rise as it typically would, overbank transfers from Hume Dam became a necessity to appropriately manage the risk of a delivery shortfall in the months ahead.
    • Undertaking these transfers resulted in in losses which are higher than similar past years. This difference was driven by the combined effect of the consistently high temperatures, below average to very much below average rainfall, and low tributary inflows.
    • If transfers of the magnitude undertaken had not been made the risk of a delivery shortfall in summer would have escalated. Ensuring Lake Victoria has enough water in it ahead of the peak summer demand period is critical to ensuring all demands can be met. Without these transfers, the main objective of operations – which is to deliver state water orders, may not have been met.
    • The ability for river operators to employ alternative arrangements is limited when delivering against the overarching operating objectives. For example, if transfers at rates above channel capacity were to be avoided this year, they would have had to commence as early as May 2018. While this option may have reduced the losses, it would have increased the risk of a spill. For 2018–19, the risk of spill at Lake Victoria during June and July was assessed to be about 90%. Commencing transfers earlier would have increased this risk. Based on this relatively high risk of spill, the judgement at the time was to delay commencing transfers.
  • In addition, environmental water holders decided to extend the period of inundation until late December, after operational transfers started reducing in early November. 

Conveyance losses

  • Losses occur when water evaporates, is used by plants or seeps into the ground. These losses are factored into water orders through ‘conveyance’—which is the water needed to deliver a water order.
  • Conveyance losses vary from year to year, depending on demand for water and conditions including rainfall, soil condition, heat, wind and inflows from tributaries.
  • Drought and sustained hot conditions across southern Australia, as well as the need to make water available when and where it is needed, all impacted on losses in 2018/19. In 2018/19, losses in the Murray system were higher than average due to high demand, low inflows, drought and hot conditions.
  • The Losses Report (which will be updated in late 2019) outlines the losses for the 2018-2019 period. 
  • Figure 14 (below) on page 20 of the Losses Report is a useful reference.  It shows that losses measured against volume delivered tracked slightly higher than in recent years.
  • This year, with the current climate outlook predicted to remain hot and dry, the MDBA expects conveyance losses will continue to be higher than in an average water year. The MDBA plans to publish the estimated conveyance losses for this water year in March 2020, once the analysis of the summer period has been conducted.
  • The connection between conveyance loss and allocation is addressed in the Losses Report at sections 5.1 and 5.2.
  • Although conveyance loss may have an impact on water availability, the magnitude is small when compared with the impact of low system inflows.
  • Conveyance losses are in fact relatively stable whereas the true (and significant) variability is found in inflows, which are driven by climate and rainfall.

Figure 14 Conveyance as a percentage of total deliveries per regulated water year. For 2018–19, estimates on the annual conveyance and deliveries have been forecast based on current conveyance and deliveries trends.

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