Jennifer Marohasy

a forum for the discussion of issues concerning the natural environment

Murray River

New Canal Development at Bottom of Murray Darling: With Freshwater

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The South Australian government dammed the Murray River’s estuary making lakes Alexandrina and Albert totally dependent on the Murray River.   That was in the 1930s.

More recently the South Australian government has been encouraging the subdivision of land around the shores of Lake Alexandrina.   That’s irresponsible.

Now its approved the subdivision of land on the edge of Lake Albert.  Apparently it’s to be a canal development with the canals full of freshwater.

I guess that’s just another vested interest to join all the others around Lake Alexandrina and Albert lobbying for more of the waters from the upper Murray and Darling.

Yep.  On my drive home today on Greenhill Rd., I saw this huge sign advertising lifestyle lots for sale called “Meningie Waters”.  Here’s a description from the local newspaper…

“Coorong District Mayor Roger Strother said plans for the development had been delayed for the past six years because of drought with some adjustments made to the design to cater for a similar situation.

“Originally the canal system was suppose to be connected to the lake but now it won’t be,” he said.  Mayor Strother said developers had taken into consideration the environmental needs of the lakeside
township and had met all protocols.

“This is being developed on a low salty flat area so won’t affect any wildlife in the lake,” he said.

“They plan on using a lot of groundwater to fill the canals and will have to pump some water in.”

From Charlotte R.

http://www.murrayvalleystandard.com.au/news/local/news/general/meningie-set-for-population-explosion/2446288.aspx

http://www.meningiewaters.com.au

http://www.facebook.com/MeningieWaters

SA Minister Caica Needs to Read My Report

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FRESH water allocated to the Lower Lakes in the Murray-Darling Basin Plan is a “waste” and only serves to maintain an “artificial” environment, a new report says…

Reports Lauren Novak and Ken McGregor from the Adelaide Advertiser got that much right.

Their article is available online here http://www.adelaidenow.com.au/news/south-australia/water-must-mix-in-the-lower-lakes-says-new-murray-darling-report/story-e6frea83-1226281052851

Comment in their article by State River Murray Minister Paul Caica that the Lower Lakes were not estuarine before construction of the sea dykes is nonsense. Lake Alexandrina is the central basin of a typical southern Australian barrier estuary.

To understand something of the long and short history of the Murray River’s Estuary read my short report

‘Plugging the Murray River’s Mouth: The Interrupted Evolution of a Barrier Estuary’

at https://jennifermarohasy.com.dev.internet-thinking.com.au/wp-content/uploads/2012/02/Plugging-the-Murray-Rivers-Mouth-120212.pdf

It’s a Barrier Estuary: Duh!

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IN South Australia the Coorong fishermen say that before irrigation, before the weirs, locks, levees and barrages (sea dykes), the Murray River would flog down from September until maybe Christmas, filling the lagoon, then out the mouth. By Christmas, flow had usually slowed and water levels dropped right down. Then when the South Westerly wind picked up the sea would pour in through the mouth and work its way across the lake.

So Lake Alexandrina was fresh in spring and summer, but salty by autumn.

What the old fishermen describe is an estuary: a transition zone. The Murray River had a barrier estuary with a central lagoon, Lake Alexandrina, and a sand barrier, the Younghusband Peninsula. A single, narrow and shallow inlet that often closes over is also a characteristic of barrier estuaries.

There are many barrier estuaries along the southern Australian coastline including Lake Illawarra just south of Wollongong. According to the Lake Illawarra Authority’s management guide, freshwater flows into the lake from the escarpment and salty water from the ocean tides and therefore it is an estuary. There are 70, of these Intermittently Closed and Open Lakes and Lagoons, known by the acronym ICOLL, from Sydney to the Victorian border. A significant issue is management of the risk of flooding when their ‘mouths’ close over. NSW State government policy doesn’t support the artificial opening of ICOLLs.

The South Australian government insists the Murray mouth, which is the inlet to Lake Alexandrina, be kept open. In fact since European settlement there have been many schemes devised to change the Murray’s mouth to make it deeper and wider, including through blasting and dredging and more recently through water reform.

There is this invented narrative that the Murray’s mouth closes over because greedy upstream irrigators have stolen all the water, but the reality is Barrier Estuary’s close over naturally. The long-term solution is to remove the Murray Mouth barrages – the sea dykes – that have interrupted the evolution of this system and so let it develop to a fully mature state. Mature barrier estuaries tend to be fully tidal.

The sea dykes dammed the estuary making it totally dependent on river flows. Stopped the tide. Limiting natural scouring of the sea mouth in spring by the river flow and in autumn by the Southern Ocean. Not surprisingly the hydrology and geomorphology of the Murray’s mouth has changed with sand that used to shoal behind the mouth consolidating into Bird Island that continues to grow and may one day permanently plug the Murray’s mouth.

Indeed Federal Water Minister Tony Burke can buy back all the water from all the irrigators across the entire Murray Darling, but this will have very little real impact on the Murray’s mouth.

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To learn more about barrier estuaries and why Lake Alexandrina was once part of a wave-dominated barrier estuary and which sea dyke should be removed first read my latest technical paper ‘Plugging the Murray River’s Mouth: The Interrupted Evolution of a Barrier Estuary’
at https://jennifermarohasy.com.dev.internet-thinking.com.au/publications/

Sold Down the River by Canberra

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WHEN former Labor leader Mark Latham was campaigning to win the 2004 federal election, he promised to add 450 gigalitres of environmental flows to the Murray River in his first term of government and an extra 1,500 within ten years.

Australian Greens leader Senator Bob Brown said he would return 1,500 gigalitres within five years – in half the time.

Back then 1,500 gigalitres seemed like a lot of water.

In a June 2003 interview for ABC Television’s Four Corners, the late Peter Cullen from the Wentworth Group of Concerned Scientists also mentioned 1,500 gigalitres and indicated that volume was scientifically derived.

In their Blueprint for a National Water Plan, the Wentworth Group proposed the water be returned through an annual incremental increase of 100 gigalitres for environmental flow. Based on this 2003 plan, by last year at least 800 gigalitres would need to have been returned to the river.

In fact, when campaigning during the 2010 federal election Julia Gillard said over 900 gigalitres had already been recovered.

The Wentworth Group should be happy with progress.

But it isn’t.

The group now claims no less than 4,000 gigalitres must be returned to the Murray Darling river system. The Australian Greens are also now claiming that a minimum of 4,000 gigalitres must be returned to ensure the Murray River’s survival and 7,600 gigalitres if it is to be healthy.

What has precipitated such a momentous change in the volume of water required to save the river?

In 2003 the water was apparently needed because of declining water quality and rising river salinity. This was shown to be a furphy: river salinity levels had been falling since the early 1980s since implementation of the salinity management strategy of the Murray Darling Basin Commission.

So now less, not more, water should be needed. But the focus has switched to the bottom of the system with claims more water is now needed to keep the Murray’s mouth open.

Professor Cullen was talking about the Murray’s mouth in that June 2003 Four Corners interview. Had he mentioned the need for a minimum of 4,000 gigalitres back then it would have been considered greedy.

Not any more! Expectations have changed.

I put the change down to two initiatives lead by former prime minister John Howard. In 2007 the Water Act became law, creating priority for environmental water. In the same year $10 billion was allocated for implementation of the associated Murray-Darling Basin plan.

Thanks to Mr Howard, Ms Gillard now has a legal obligation to send a volume of water about equal to the total current baseline diversions for the NSW Murray (1,812/year GL) and also the Murrumbidgee (2501 GL/year) to South Australia every year.

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First published in The Land newspaper on January 19, 2012

Talking at the Sydney Institute about the Need to Restore the Estuary

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I will be speaking at the Sydney Institute on Wednesday 8th February on the need to restore the Murray River’s estuary.

More information here: http://www.thesydneyinstitute.com.au/functions/weekly-seminars/

My talk will be published in the on-line journal The Sydney Papers. The talk will be uploaded on to The Sydney Institute’s website as a podcast soon after the event. Also, it is possible that the talk will be filmed by APAC – Channel 648 on Foxtel and Austar – and will be shown in full soon after the event.

Sustaining Australia on 2,500 Gigalitres of Water

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Yesterday a Murrumbidgee food producer, Virginia Tropeano, had a letter printed in the local Murrumbidgee ‘Area News’ explaining that in an average rainfall year it take 5,000 gigalitres of water to keep the Lower Lakes artificially fresh.

Because of the sea dykes across the bottom of the Lower Lakes, they are totally dependent on water from upstream. In drought years this makes the Lower Lakes completely dependent on water in upstream storages. The only really large and reliable storages in drought years are in the upper Murray and Murrumbidgee catchments because they are the only snow fed catchments.

The Premier of South Australia, Jay Weatherill, wants 4,000 gigalitres more freshwater each year for South Australia as guaranteed supply. Because the Lower Lakes are Ramsar listed and because of the way the Water Act has been written, he is likely to get this water even if he has to take the Murray Darling Basin Authority to the High Court.

I think that in a good year, the most water that is ever allocated for food production in the Murrumbidgee is 2,500 gigalitres. Can someone verify this figure for me? Assuming I’m about right, Mr Weatherill wants all of this water and more.

If you have continued to read this far, and you are not an irrigator, you are probably getting bored with my use of these meaningless figures of thousands of gigalitres. So help me make this a more interesting story.

How much food can 2,500 gigalitres produce?

Farmers in the Murrumbidgee use about this volume of water to produce food.

What types of foods do they produce and how could the total volume, or caloric equivalent, be described in a meaningful way.

For example, can someone let me know for how many weeks or months the population of Australia could survive on food produced from 2,500 gigalitres of water?