The Murray-Darling Basin Plan has been politically fraught and mired in scandal. But environmental monitoring suggests that the health of the rivers is indeed improving – even if it will take decades.
The Murrumbidgee River is one of several sites in the Murray-Darling Basin where improvements are being detected.
Amid the politics, it’s sometimes easy to forget that the Murray-Darling Basin Plan was originally designed primarily to restore the rivers’ environment. While questions have been raised over the plan’s governance, economics, and political commitment by the states, it is important to note that, more than five years after the plan’s adoption, the environmental benefits are slowly but surely being seen.
The Long-Term Intervention Monitoring Project began in 2014 to monitor and evaluate environmental outcomes from Commonwealth environmental water – the water being delivered into the Murray-Darling Basin by the plan.
The seven monitoring sites. Author provided.
We are leading independent teams of researchers and consultants in monitoring seven selected areas across the Murray-Darling Basin, and then scaling up those results to deduce the health of the basin as a whole.
It’s not widely known what environmental water can and cannot do, and how different environmental indicators will respond at different rates. The Basin Plan’s objectives focus on fish, bird and vegetation communities – and in all of these areas, the changes will take time.
What’s more, Commonwealth environmental water is a relatively small proportion of what once flowed through these systems. The government currently holds entitlements to 1,836 billion litres, which is less than 6% of average system inflows (the rainfall that makes it into the river system).
This is not enough water to restore natural flow patterns. Along with other constraints, such as the pressure to keep water off floodplains, this means that managers need to be extremely selective about where, when and how water is delivered for environmental benefits.
What are we monitoring?
While we are monitoring fish, birds and vegetation to allow us to measure progress towards the Basin Plan’s objectives, we are also monitoring shorter-term responses. These responses provide data on environmental processes that will allow us to predict whether we can expect the Basin Plan ultimately to deliver on the promised long-term improvements.
A good example of this is golden perch, a threatened and iconic native fish species in the Murray-Darling Basin. Long-term changes in the adult population will only be seen if shorter-term processes, such as migration and spawning, occur. Environmental water should help these processes, and we are monitoring those outcomes.
Warrego-Darling: environmental water has maintained flows in a system that would have otherwise dried to a series of isolated pools, maintaining food webs and stimulating fish breeding.
Besides reporting progress, our monitoring program also allows us to make predictions of what the system might have looked like with different environmental flows, or with no environmental flows at all.
In the Lachlan River in New South Wales, environmental water has been used to support a major bird breeding event by extending the period of flooding. Without this water, nests would have been abandoned, leaving thousands of fledglings to die.
Straw necked Ibis chicks from the Lachlan River. Mal Carnegie/Lake Cowal Association, Author provided
We also share our results with environmental water managers to help improve the effectiveness and efficiency of environmental water delivery – a process called adaptive management. In the Goulburn River in Victoria, we have learned that the release of environmental water to help riverbank vegetation is more effective if delivered earlier in spring. Riverbank vegetation has now improved so much that metal pins being used to monitor erosion and sediment deposition can’t be found without a metal detector.
In it for the long haul
One criticism of the Basin Plan is that there is no evidence yet of basin-wide improvements. For some indicators this is to be expected because of the long time frames of response of the Basin Plan objectives. However, we have already reported on basin scale changes of other indicators, such as vegetation.
Environmental water release to improve water quality in the Edward-Wakool system. Photo: Commonwealth Environmental Water Office, Author provided
The politics of the Murray-Darling Basin Plan will probably always be fraught. But as the group charged with assessing environmental progress, we want the debate on its effectiveness to be underpinned by sound evidence from independent experts.
So, while the Basin Plan’s objectives will take a long time to be realised, there are positive signs that it is slowly achieving its major goal of improving environments in the Murray-Darling Basin, underpinning more sustainable social, environmental and economic outcomes into the future.
This article was coauthored by Mark Southwell, Geomorphologist, Eco Logical Australia; and Shane Brooks, Director, LitePC Technologies.