Barmah choke capacity: NSW claims 50 per cent while Victoria demands 70 per cent

NSW’s claim to half the Barmah choke’s capacity will massively increase Victorian irrigators’ risk of summer delivery shortfalls.

Victoria’s Lower Murray irrigators face being throttled by NSW’s claim to half the Barmah-Millewa Choke’s capacity.

The NSW Government is set for a showdown with Victoria over its claim to half the Barmah-Millewa choke’s capacity.

The claim massively increases the risk of delivery shortfalls for Lower Murray Victorian irrigators, given they use 70 per cent of the choke’s capacity during the peak of summer across the Boundary Bend, Robinvale, Liparoo, Mildura, Merbein and Red Cliffs districts.

Below the choke Victorian irrigators hold 897,066 megalitres of high reliability water shares, compared to just 166,894 ML of high security and 372,860ML of general security water shares held in NSW.

It means any heatwave-driven surge in summer demand for water would force NSW and Victoria into a major dispute, as they try to thrash out how much of their irrigators’ water they can push through choke, with its limited capacity of just 9200ML a day.

Victorian Water Minister Lisa Neville said “we expect that any shortfall sharing will reflect rights to water and how water is actually being used.

“We’ll continue to work with the other states to deal with any shortfall risk and ensure sharing is based on irrigators’ rights and entitlements.”

But that would mean Victoria claiming at least 70 per cent of the choke’s capacity, a proposal the NSW Government has already rejected.

NSW Water Minister Melinda Pavey’s office says the choke’s capacity must be shared on a 50-50 basis, in the same way the two states divvy up the Murray’s inflows and storage capacity of Lake Victoria, the Menindee Lakes, Hume and Dartmouth Dams.

“In various inter-jurisdictional forums, NSW has provided advice that its position on sharing channel capacity is a 50:50 arrangement,” Ms Pavey’s spokeswoman said.

“NSW is currently developing a draft Shortfall Response Plan that will outline how it would implement a shortfall, should one be declared for NSW, by agreement by the Basin Officials’ Committee, Ministerial Council or by the Minister.

“It is proposed that the SRP contain an explicit statement of NSW’s position on sharing channel capacity, that is 50-50.”

As it stands the Murray Darling Basin (Schedule 1 to the Water Act 2007) is mute on the issue of how the Barmah-Millewa channel capacity is shared between NSW and Victoria.

However the agreement states that if ministers cannot reach agreement the matter must be referred to the chief justice of Tasmania’s Supreme Court, who is likely to appoint the Australian Competition and Consumers Commission as arbitrator.

NSW constrained below choke development, up until November 2004, when native title claims over the western lands pastoral leases were finally resolved.

In contrast past Victorian Coalition and Labor Governments have fuelled massive growth in irrigation development below the choke, allowing water to be traded out the Goulburn and Torrumbarry systems to horticultural developments, shifting demand to the peak of summer.

It was not until July 2019 that Victorian Water Minister Lisa Neville finally stepped in call in all works licence applications for extractions from the lower Murray to ensure they did not increased risks to the environment or entitlement holders.