Another battle has broken out in the murky war over the Murray-Darling Basin plan, with Victoria and South Australia in disagreement over the level of water cuts and two different groups — including the SA government — now threatening that the current basin plan is illegal.

Is the Murray-Darling Basin plan illegal?

Two different groups are currently arguing yes. First, the Environment Defenders Office of Victoria released a document yesterday examining the legal issues around the basin plan, arguing that the basin plan is illegal as it does not adequately comply with the 2007 Water Act.

“In our view the proposed basin plan (draft plan) does not comply with the act in a number of respects,” says the report. “In addition, it is clear from the draft plan and the associated explanatory materials that the approach the MDBA has taken in the development and drafting of the basin plan has been to consistently give provisions their weakest interpretation and/or give effect to them in the weakest way.”

The report goes on to note that the Water Act prioritises “environmentally sustainable” levels of water over economic and social factors, although the current basin plan does not.

Why does the Murray-Darling Basin plan have to be in accordance with the 2007 Water Act?

This paragraph from the legal analysis done by the EDO Victoria nicely outlines the conundrum that the Murray-Darling Basin Authority finds itself in and why the basin plan must abide by the Water Act:

“The MDBA is a statutory authority established by the Water Act and thus the entirety of its powers come from the Water Act. The basin plan is a statutory instrument made under the Water Act and must be developed and implemented in accordance with the Water Act. There is no ability for the MDBA to depart from the Water Act in its functions or its development of the basin plan, regardless of any political or other factors. If it does it may have breached its obligations under administrative law.”

Who else claims the plan has legal issues?

The SA government has uncovered a 106-year-old document written by a former chief justice of the High Court.

Titled Waters of Murray River and its Tributaries and Interstate Rights to Divert Them, the document was written by Isaac Isaacs — the first Australian-born governor general and an attorney-general in Australia’s first parliament — and is dated March 22, 1906.

The document apparently asserts SA’s rights over the use of water from the Murray-Darling Basin. As Michael Owen reported in The Australian: “The opinion supports a finding, according to associated legal documents archived at the time, that ‘South Australia and its residents have rights in respect and to the use of the waters of the Murray and its tributaries capable of being judicially asserted and enforced’.”

But will anyone actually take legal action?

“Our focus at the moment is definitely on trying to improve the plan,” Nicola Rivers, law reform director at the  Environment Defenders Office of Victoria, told Crikey. Rivers says she wants to encourage the authority first and also the federal water minister to improve the plan. “That’s certainly the aim of this document and there’s some solutions in there, some recommendations of how they can do that, and that’s the priority.”

But legal action is still a possibility if the insufficient changes are made to the plan. “Litigation is not usually a preferred option for people,” said Rivers. “I guess in the future you can’t rule out a legal challenge, but this sort of work is definitely the focus at this stage.”

SA Premier Jay Weatherill also noted that a High Court challenge remained a possibility for the state. He’s got federal allies, with South Australian senator Nick Xenophon telling journalists: “If the politicians get it wrong then maybe we need the courts to get it right.”

Federal Water Minister Tony Burke summed it up in a nice one-liner: “I think there’s going to be plenty of people playing games of ‘lawyers at 20 paces’ during all of this.”

But this isn’t just about legal issues, right?

True. The states are also in an environmental tussle with the SA government saying not enough water will be returned to SA and the Victorian government claiming that the current 2750 gigalitres figure is too high for Victorian farmers.

The Victorian submission to the Murray-Darling Basin Authority claims that “the MDBA’s focus on the amount of water recovered as a measure of environmental health, rather than environmental outcomes, is incorrect and promotes an inefficient use of water.”

But in South Australia, a new report by the Goyder Institute for Water Research (an institute established in 2010 by the SA government, the CSIRO and several SA universities, to support and manage SA’s water supply) examined the likely ecological consequences of the plan and found that not enough water would be returned with the current 2750 gigalitres figure.

“Overall, there are important benefits identified under the BP2750 scenario that has been analysed, however, for much of the area of the floodplain environmental assets that require medium to high flows, the environmental water requirements are not met,” found the report.  “Thus, the ecological character of the South Australian environmental assets, as defined in current water management plans, is unlikely to be maintained under the BP2750 scenario.”

“On the basis of this report, the MDBA’s plan does not even provide a good place to start,” said Weatherill in a statement.