CJ, by referring to overallocation of farm irrigation licences, you paint the picture that farmers are taking out water all of the time, which is blatantly not true. QLD is a slightly different matter as they have had different laws around allocation and pumping rights (plus the attitude that water is only wasted if allowed to get into NSW). NSW has long had allocation caps, although in good years, allocations might be 120+%. In the last several years for much of the state, allocations have been between 0-20%. Allocations are decided based on the water available, with priority to environmental flows. Mind you, the idiots that decide what these flows should be have in the recent past done things like flooded redgum forests, let the water sit and stagnate, then wonder why all the fish are dead.

Irrigation is not responsible for the current flow decline in the Murray, drought is. If it were not for the infrastructure built to support irrigation, the Murray would have reduced to a trickle 2 or 3 years ago.

The barrages at the Coorong must be opened to avoid disaster, and arguably they should be left open. The certainty of flow thanks to irrigation-based infrastructure is the reason why the barrages were able to be constructed in the first place

Can I suggest that people look at the discussion in response to Jennifer Marohasy's article "Stop Complaining About the Lower Murray And Open the Barrages" of 19 June 08 at http://www.jennifermarohasy.com/blog/archives/003176.html

One contributor Luke disputes Jennifer's view that "Prior to 1940 Lake Alexandrina was a mix of seawater and freshwater, ..."

He quoted from historical documentation: http://www.jennifermarohasy.com/blog/archives/003176.html#c1675810
http://www.rivermurray.sa.gov.au/pdfs/Lakes%20History.pdf
"Before large-scale extractions of water, the Lakes and
lower Murray were rarely subjected to seawater invasions.
Long time Goolwa resident Edward Leslie Goode told an
enquiry in 1933 ‘I can remember when it was a remarkable
thing when saltwater came up to the Goolwa wharf. Now we
see saltwater in the lakes for months’. Short-lived
intrusions of saltwater would occur during periods of
low flow down river resulting in a lowered level of water
in the lakes. Even in times of these low flows, it would
appear that only small areas of the Lakes (immediately
around the Murray Mouth and into the channels towards
Point Sturt for a short distance) were affected. ..."

So the lakes were mainly fresh in their natural state?

http://www.rivermurray.sa.gov.au/pdfs/Lakes%20History.pdf
"Before 1900: In their natural state, the lakes were predominantly
fresh, with River Murray water discharging from the
mouth and keeping the sea at bay more than ninetyfi
ve per cent of the time. Water from groundwater
springs, extensive wetlands and streams in the
Eastern Mount Lofty Ranges continued to flow
through the lower Murray, lakes and mouth, even
when the upper Murray was reduced to large pools
during drier seasons. The fresh water supported
thriving ecosystems in and around the lakes and
the Ngarrindjeri people maintained permanent
settlements in the region. Early European settlers
relied on the lakes as a supply of good quality water
and on the fringing reedbeds as stock feed."

I suggest others read the preceding and ensuing discussion at http://www.jennifermarohasy.com/blog/archives/003176.html

dagget, doesn't "95% of the time" indicate not always fresh? and that over the last 5000 years 250 of them did not keep the "sea at bay" if this is true. Obviously opening the barrages will not destroy the Coorong, nor the lakes, just as it didn't in the past.
Incidently since the 30'S the lakes have been predominately "fresh", more than 95% of the time.

One might also realise that irrigation extraction in the 30's(when barrage construction began)was approx 1/3 of todays, yet salt intrusion was a recognised problem then.

Just contemplate where the lakes would be under completely natural conditions - no Hume and Dartmouth, snowy, no lochs, and thanks to natural variability record low inflows. Record lows not by a little, nor recorded over so long a timespan. The lakes would be salty today any way it's looked at, under truly natural conditions.

I find it difficult to accept that the "best" fix is to store water in man-made dams to be released at man's discretion for a man-made problem, caused by building the barrages. Only one side of nature seems to be considered by those that crow the loudest about it.

as an aside, isn't SA the only state that has announced a allocation to irrigators this year, yet SA's are calling for more water? From where exactly?

Jennifer

I am completely gobsmacked that you have the sheer gall to publish at OLO again, after your "Murray river is saved" rant of a couple of years ago. However, I read your latest piece in hope that you had learned something about eco-systems in the past two years, but apparently not.

A very basic fact which will assist your comprehension is that everything is interconnected and, as such, everything we do has consequences.

A further educational aid which would be fun for you and your family is at the following link. Who knows you may even win a prize.

Kindest regards

http://catchmentdetox.net.au/

When Sturt went down the river it may have been a period of low flow. The lakes may have been periodically flushed out by seasonally high river flows. But of course, Dam building on the Murray and tributaries is not a modern phenomenon, such that later observers recorded more frequent periods of sea water intrusion as irrigation infrastructure was built.

This article, and its mirror on her blog, seem to be yet another vehicle to attack selected targets. In this case "the greenies" (again) and "the South Australians". Never mind that the greatest overallocator of water licences in the basin was NSW. Witness Iemma almost falling over himself to palm of responsiblility for water to the Feds... why WAS that do you think?

Anyway, removing the barrier may be the least worst solution now...

But I would like to extend Jennies argument. She proposes that we should remove this unatural structure and return the river to its natural state. Hey Jenny, thats a great idea, lets extend that to all the unnatural barrages and walls up the river. Surely you must logically agree to that? Surely, after heroically proposing the restoration of the lakes to natural conditions, how could you deny that the troubled river not be treated in similar fashion?

Oh wait... you wouldn't want to upset your base, would you?

Thanks, SP, for pointing out what appears a glaring contradiction in Jennifer's case. On the one hand the removal of the unnatural barrier at the mouth of the Murray is beneficial and necessary, but on the other hand, leaving in place the many other unnatural barriers to the flow of the water in the Murray River is not to be questioned.

On 15 August, Dr Paul Humphries of the Charles Sturt University Institute for Land Water and Society wrote and excellent article "The drought we had to have?" for Science Alert at http://www.sciencealert.com.au/opinions/20081508-17809.html

The article shows how the damming of the Murray Darling River system, whilst it saves water that would other wise flow into the sea, has detrimental effects on the river's ecosystem:

"The typical large dam captures runoff in winter and spring, holding it until the growing season and warmer weather gets underway, and then releases it downstream. This results in a reversal of the flow regime: where naturally it would have been high in winter and low in summer, it is now low in winter and high in summer. Many of our large dams also have bottom releases. Large bodies of water become stratified - with cold water sinking to the bottom and warm water floating on top. Consequently the water that is released is considerably colder than it would have been naturally. The water can be more than 10 oC cooler downstream of a dam than in a nearby un-dammed river. And since most of the animals that live in rivers are cold-blooded, they are seriously affected by this ‘thermal pollution’: reproduction and growth are intrinsically tied to water temperature in many species. Imagine living in your natural environment one minute, and then the next, the medium in which you live is in short supply when normally it is abundant, and is plentiful when it is usually limited. And furthermore, that in summer it now rarely gets above 16 oC when once it reached close to 30 oC. Now that’s climate change!"

(tobecontinued)