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Published: 09 January 2019   •   Media statements

The recent tragic fish deaths in the Lower Darling are a terrible reminder of the effects drought can have on our environment.

Unfortunately, the main causes of this distressing event are the lack of water flowing into the northern rivers, and the impact of 100 years of over-allocation of precious water resources throughout the entire basin.

Lack of water during drought leads to water quality issues, and can provide prime conditions for blue green algae to thrive. When previously high water temperatures drop quickly, as they did briefly recently, algae dies and as it decomposes oxygen levels fall below critical levels, causing the fish to die. Without more water available to flow through the system, it is possible more fish will die during summer.

With rivers running dry and water storages across the northern Murray–Darling Basin at 20 per cent, drought conditions are affecting communities, businesses, animals and the environment.

This is upsetting and a concern for local communities, businesses and authorities.
It is understandable that people are looking for answers. Some have alleged that the operation of the Menindee Lakes has caused water quality problems and the fish deaths.

The Menindee Lakes are currently under the sole control of New South Wales. This occurs when the water in storage falls below 480 gigalitres as it did in December 2017.

There is a written agreement where New South Wales, Victoria, South Australia and the Commonwealth direct the Murray–Darling Basin Authority (MDBA) to call water from the Menindee Lakes to meet consumptive and environmental needs. This agreement dates back to the 1960s when the lakes were developed as a storage. The agreement reflects the fact that when the Menindee storages were created they impeded flows of water through to Victoria and South Australia.

The MDBA calls on water to fulfil New South Wales, Victorian and South Australian entitlements when there is water in the Menindee lakes. The Menindee Lakes have been carefully managed by New South Wales since December 2017. Currently, the lakes hold about 67 gigalitres of water.

The MDBA draws water from the Menindee Lakes first because Dartmouth and Hume dams are more efficient as they don't have the high evaporation rates of the Menindee Lakes. The figures speak for themselves, Menindee Lakes can hold up to 2,050 gigalitres and is estimated on average to lose 426 gigalitres a year to evaporation, and up to 700 gigalitres a year when the lakes are full. Dartmouth Dam, by comparison can hold up 3850 gigalitres with net evaporation of close to zero.

When it comes to drought none of us can control the weather. But we can control the level of use and that is where the Basin Plan comes in.

With bipartisan agreement, from six jurisdictions, governments agreed to the Murray–Darling Basin Plan in 2012. The Basin Plan won't be fully implemented until 2024 so we're halfway through and it will take decades to reverse the effects of 100 years of over allocation of water but we're on the right path.

The Basin Plan has already made a permanent reduction in the amount of water available for production. Secondly, it sets aside water for critical human water needs; and thirdly, it holds water for the environment alongside other uses.

It is not possible to drought-proof the Basin, but the Basin Plan can help us prepare for future droughts by providing water for the environment as well as water for irrigators, and increasing system health so it can recover from drought better and more quickly.

We've already started. Just last year 23 gigalitres of Commonwealth and NSW water for the environment was released, which was able to provide some relief across 2000 km to the Menindee Lakes.

Governments are doing their best to manage drought conditions and water quality issues now. What the Basin Plan gives us is new tools in the future; for example governments are looking to change the way the Menindee Lakes are managed to help fish and local communities. It's going to be important for communities to get involved.  

In the long run we need significant rain and inflows into the system and across the system to break this drought and to give the northern Basin the best chance to recover and build resilience before the next inevitable drought.

Phillip Glyde
Chief Executive Murray–Darling Basin Authority


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