OVER the last decade, the Wentworth Group of Concerned Scientists, and other groups, have successfully lobbied for the environmental needs of Australia’s river systems to have a guaranteed first priority call on water. This became reality with the Water Act 2007 that not only gives environmental needs priority over industry and community, but within this category, environments listed under international conventions are given particular priority.
The Water Act 2007 imposes a legal limit on the amount of water that can be diverted for non-environmental purposes and, through implementation of the Proposed Basin Plan, will result in a significant transfer of water from food production to the environment.
The Proposed Basin Plan does not specify where the new environmental water recovered under the plan will be used i.e. which environments will benefit most. However, it is generally acknowledged that most of the water will be sent to the Lower Lakes in South Australia. This is because the legislation specifies that the new diversions limit must preserve the environmental values of key sites within the Murray Darling Basin in accordance with international conventions (i.e. these environments are first priority). The Lower Lakes are vast coastal lagoons at the termination of the Murray River that are listed as freshwater lakes under the international Ramsar convention. According to key reports the lakes are currently suffering from inadequate freshwater flows.[1]
According to the Proposed Basin Plan the Murray Darling Basin, presumably including the Lower Lakes, can be returned to ecological health if 2,750 GL is returned to the environment. But South Australian Premier Jay Weatherill has signalled that unless this figure is increased to somewhere between 3,500 and 4,000 GL South Australia will launch a High Court challenge because this is how much water is needed to preserve key environments just in South Australia.
Such a legal challenge from South Australia would likely be prefaced on the Proposed Basin Plan failing to met the objectives of the Water Act 2007; in particular that the Basin Plan must be prepared to give effect to the relevant international conventions.
Indeed, given current arrangements and despite relatively large volumes of water being channelled down to these lakes, including during the recent drought, they are an ecological disaster. However, the solution is not more fresh water.
Because the Lower Lakes are Ramsar listed, the Australian government is obliged to report on their ecological health at regular intervals. In the last report the Australian government acknowledged that ‘the site’ had been in ecological decline for at least 20 to 30 years prior to listing in 1985, with the rate of decline increasing since listing in part due to drought conditions. In particular the Australian government acknowledged that nearly half of 53 key functions were described as being ‘of alarm’ and a further third ‘of serious concern’.
A key issue for the ecological health of the Lower Lakes is the sea dykes (the barrages), that have dammed the estuary. To quote Bob Bourman from the University of Adelaide and coworkers [2]:
“Originally a vibrant, highly productive estuarine ecosystem of 75,000 ha, characterised by mixing of brackish and fresh water with highly variable flows, barrage construction has transformed the lakes into freshwater bodies with permanently raised water levels; freshwater discharge has been reduced by 75% and the tidal prism by 90%.”
Peter Gell from the University of Ballarat writing in the recently published The Sage Handbook of Environmental Change has commented that the natural state of the Lower Lakes was tidal, that the lakes have been incorrectly listed as freshwater in the International Ramsar Convention, and that until their natural estuarine character is recognised it will be difficult to reverse the long-term decline in their ecological health.[3]
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[1] See in particular ‘The Murray Futures Lower Lakes and Coorong Recovery: Securing the Future: a long-term plan for the Coorong, Lower Lakes and Murray Mouth’. According to the plan ecological values of the Coorong, Lower Lakes and Murray Mouth can only be maintained if there are adequate freshwater end-of-system flows and thus the key long term management action is to secure adequate freshwater. The planning document does not specify the specific amount of water required but suggests a mean total end of system flow of 5,550 GL would result in improved management.
[2] Marine Geology 170:141-168
[3] See Chapter 27. Human Impacts on Lacustrine Ecosystems, page 595
Jennifer Marohasy BSc PhD has worked in industry and government. She is currently researching a novel technique for long-range weather forecasting funded by the B. Macfie Family Foundation.