Victorian and southern NSW irrigators forced to meet Darling River shortfalls

It’s time to hold those who want to continue floodplain harvesting in the northern Murray Darling Basin to account, say Southern Riverina Irrigators.

Accountability needed: Floodplain harvesting, not just climate change, has drained the Darling River of flows, say Riverina Irrigators. Picture: Toby Zerna

THE Darling system has stopped providing its end-of-system flows to the Murray River.

We argue floodplain harvesting has played a major role in curbing those flows, which has had disastrous impacts on the environment and those of us in the south.

In the past the Darling contributed 39 per cent of the 1850 gigalitres that NSW and Victoria delivered to South Australia in annual entitlement flows, which should not be confused with the total flow across the border.

But now it’s left to Murrumbidgee, Murray and Goulburn irrigators to make up most of that 721.5GL, due to overdevelopment in the north of the Basin.

According to the Natural Resources Commission review of the Barwon-Darling Water Sharing Plan, the estimated volume of water stored in turkey nest (dams) in the Barwon-Darling is 289Gl, with another 4039GL in other turkey nest and hillside dams in the upper catchment.

That’s a vast volume of storage and well beyond the 210GL allocated for floodplain harvesting across NSW and Queensland.

So, what’s the solution?

It may be as simple as requiring the Darling to contribute its long term average contribution to the SA entitlement.

Namely, 721.5GL each year from Menindee Lakes. It can be left to the relevant stakeholders in the north to determine between themselves what is the most equitable way to ensure these flows return.

Ultimately, if NSW and Queensland commit to providing 39 per cent of SA’s annual entitlement from Menindee Lakes each year, they can make their own adjustments with respect to how they deal with this explosion in on-farm storages and diversions.

If the northern basin cannot contribute 721.5GL annually, the equitable solution is that it uses the “borrow” system – a system that has been effectively employed in the southern basin with respect to Barmah Millewa or Snowy Hydro water.

The water can be borrowed from CEWH (or any other willing party) and a cease to pump order can be put in place to ensure that adequate flows move down through the system.

If floodplain harvesting extractions are greater than anticipated, this can simply be offset by reducing the amount of water that can be extracted by other licence holders. This is the equity that was always intended by the Murray Darling Basin Cap.

As a concession, and due to the higher variability of flows, in years where Menindee can contribute more than 721.5GL — which would allow more water to be kept in southern head storages — a credit can be given to the northern basin.

By implementing this simple change and requirement, southern NSW, Victoria and sometimes South Australia (ie. when they are forced to endure “special accounting” due to low volumes in the storages) will no longer be required to underwrite the lack of flows down the Darling.

This approach would satisfy the environmental managers and communities throughout the Basin and would go a long way towards achieving the goals of the Basin Plan.

• Southern River Irrigators is SRI is a lobby organisation for Murray Irrigation Limited and southern NSW Riverina irrigators

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