Australasian Science: Australia's authority on science since 1938

Shifting the Watermarks

By Tim Stubbs

The draft Murray-Darling Basin Plan is confused at best and deceptive at worst.

The full text of this article can be purchased from Informit.

The latest draft Murray-Darling Basin Plan is part of a reform process that will cost taxpayers an estimated $8.9 billion to establish environmentally sustainable levels of take (ESLT) for the rivers of the Basin.

Currently it appears that the money will be spent but the outcome not delivered because the draft plan is a confusion of politics, opinion and misrepresentation. This is illustrated by one of the draft plan’s supporting documents in which the Murray-Darling Basin Authority (MDBA) states that “through considered judgement” it established “a range of sensible ESLT options for further and more robust analysis using the hydrologic models”.

The critical factor is how these “sensible ESLT” numbers were selected. The MDBA used three “studies” to guide its selection.

The first was an analysis undertaken in the Guide to the Basin Plan in 2010, a document released 13 months before the current draft plan. The analysis showed that raising the average annual end-of-system flows by 3856 GL would have a high uncertainty of achieving environmental objectives, while raising average flows by 6983 GL/y would have a low uncertainty of achieving those objectives.

However, for the purpose of selecting its “sensible ESLT options” the MDBA chose a range of 3000–4000GL/y because “reductions in current diversions above 4000 GL/y have been judged to be beyond the...

The full text of this article can be purchased from Informit.

Tim Stubbs is an environmental engineer with the Wentworth Group of Concerned Scientists.