Wednesday, November 30, 2106

BLACK WATER: The MDBA says environmental programs on the Murray did not cause high levels of backwater but actually goes a long way towards healthier ecosystems.

BLACK WATER: The MDBA says environmental programs on the Murray did not cause high levels of backwater but actually goes a long way towards healthier ecosystems.

Joyce support

I wish to express my support for the comments from the Deputy Prime Minister Barnaby Joyce regarding extra environmental flows as part of the Murray-Darling Basin Plan.

Under the legislative requirements of the basin plan, the 450GL of additional environmental water on top of the 2750GL target can only be delivered in ways that deliver positive or neutral socio-economic outcomes for our region. 

We have sold out our communities for 1986 gigs of water already under the current basin plan but of course for this mendicant state no amount of largess will satisfy. 

South Australia will say that clause 17.2.b of the basin plan has to be amended or the assessment of "socio economic" effects of a further 450GL of water coming out has to be done by their conservationist allies in the CSIRO meanwhile the state of South Australia have had some vey big wins in the deals to build the country’s Navy ships and submarines while also having the GST deal of the century. 

One only has to look at Collarenebri in northern NSW with all the water gone, town size halved and poor people are now poorer. 

The communities of Indi are at the risk of the same fate if our local member Ms McGowan, through her silence on this most vital of issues, continues to not stand up for our communities who rely so heavily on water. One only has to visit the vacant shops in Wodonga, Wangaratta or Benalla to see the devastating effects that the current MDBP has had on our communities. 

I respectfully ask that Ms McGowan supports the revised MDBP. 

Marty Corboy, Milawa 

Blackwater addressed

The blackwater events this season have resulted in significant stress and fish deaths in parts of the Murray system due to low oxygen levels in the water. It has also resulted in a fair bit of misinformation.

We’ve seen relatively widespread blackwater this season because the floods in parts of the Murray and its tributaries reached so far across the floodplain they mobilised up to 25 years’ worth of organic matter. An immense amount of leaves, wood, bark and other high-carbon material builds up over that many years.

In the not too distant past, these higher floodplains had had more regular flushing than the current river regulation and land practices allow. These days flushing away the build-up of matter is limited mainly to the lower floodplains through a complex process of environmental watering (it’s never a case of “simply adding water”). Regulated flooding of Barmah-Millewa and Gunbower forests prior to this year, for example, shifted carbon out of those areas and reduced the severity of this current event.

One thing that’s clear is that environmental watering and works programs on the Murray did not give rise to the backwater we’re now seeing. In fact environmental watering goes a long way towards healthier ecosystems by flushing the lower floodplains. Without it, the current events could have been even worse.

The MDBA, local land and water managers, environmental water holders and scientists continue to devote a lot of effort to exploring the causes and impacts of blackwater. The investigation into the 2010-11 floods and other events found that actions such as regularly flushing carbon from the floodplains helps but that it is very difficult to prevent and manage large scale blackwater, particularly in river systems regulated to support development.

Right now these same people are working to mitigate the impact of this latest event. Environmental water is being used to create pockets of refuge and dilution. 

The benefits of all this work are highly localised when you consider the size of the area affected, but worthwhile particularly for creating refuges to help fish populations recover across the system. 

Carl Binning, executive director, environmental management, Murray–Darling Basin Authority

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