Southern discomfort: water losses in the southern Murray Darling Basin

Environmental health Rivers Agriculture Fresh water Irrigation Murray-Darling Basin
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Decisions by the Murray Darling Basin Authority (MDBA) to flood the Barmah-Millewa forest in 2018-19 and drain Menindee Lakes in 2016-17 have caused environmental damage and reduced the amount of water available to NSW Murray water users. These decisions prioritised South Australia’s entitlement and new water demand from corporate nut plantations around the SA border above water holders in the River Murray, including many family farms and environmental water holders.

High demand for water at the SA border has been driven by “insatiable overseas demand for crops like almonds”, which has prompted “a flood of investment from local and overseas agribusinesses and pension funds.” At the same time, “2018–19 has been a low rainfall year across the southern Basin putting it in the driest 9% of years in the historic record”. High demand and low supply of water has driven water prices to record highs and pushing many farm businesses to the financial brink.

The Almond Board of Australia notes that “river managers are experiencing increasing difficulty delivering water to meet increased demand from new horticultural development.” In an attempt to meet this demand at the South Australian end of the Murray system, the MDBA released water from the upper Murray that resulted in water exceeding channel capacity at the Barmah-Millewa “choke”. The total amount of water that was overbank was between 536 and 847 gigalitres, flooding the BarmahMillewa forest between August 2018 and January 2019.

Very little of this was environmental water. Summer flooding is unseasonal and can damage harming established red-gums and moira grass plains, which contribute to the forest being listed as an internationally significant wetland under the Ramsar Convention.

The Menindee Lakes were drained by MDBA in 2016-17, at a time when there was flooding in South Australia. If these releases had not been made, Menindee could have contributed to meeting demand at the South Australian border, reducing the need to release water from the upper Murray.

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