Mis-information vs. Evidence

(6) The freshwater/seawater issue – the misinformation and the evidence

‘A Fresh History ---’   an interesting anecdotal collection but proof of very little.

·       This document is typical of its genre – written by an amateur local historian with passionate views about the subject – co-authored (endorsed) by a highly credentialed ecologist – but it is not ecology. It is not an academic paper subjected to the usual critical analysis and peer review before publication.

·       What sets it apart from other local historical publications, however, is the extent to which it has been accepted and used by local activist groups, government water catchment groups and recently, apparently by the government agency responsible for the EIS process.

·       An intellectually rigorous research exercise would seek to examine objectively, evidence both for and against its hypothesis – and base conclusions on that evidence.

·       This document is a collection of historical data clearly selected and included for its apparent support of the thesis that the lakes have (before European settlement) always been fresh.

·       An alternative hypothesis ‘that the lakes, while fresh for extended periods, reverted to an estuarine saline mix of seawater and river water at times of low flow and during periods of drought’, has not been tested by the ‘Fresh History ---’ document. In fact despite the bias evident, some of its included data could as well support the alternative, estuarine thesis as that which the authors seek to promote.

·       An example of the bias comes very early, on page 9, with the fourth dated extract (of  204 such extracts); viz Captain Charles Sturt’s observation in 1838 of, “a strong current always setting out of the channel”, which would appear to support the freshwater thesis.

·       In fact Sturt made this observation when comparing conditions at the mouth with those on his first visit in 1830 during his epic journey down the Murray and back when the shallow mudflats made it impossible to take his whaleboat to the mouth.

·       This reality is elaborated with more detail of the differences between Sturt’s two visits, on page 17 of  ‘A Fresh History ---’ with an (unsubstantiated) conclusion by the authors that Sturt believed the 1838 conditions were normal but those evident in 1830 were not. The historical evidence could as well be used to show that flows were highly variable and support the thesis that low flows were not uncommon.

·       In his 1929 book, ‘Founders and Pioneers of South Australia’ (1978 Impresssion Page 34), A Grenfell Price describes the circumstances as follows, -

“During a subsequent examination of the mouth in 1838, Sturt found the channel from Goolwa to the outlet deep and clear. If this had been the case in 1830, a season of drought in which the river was extremely low, the first Murray voyage would have ended in disaster. “Had we, wrote Sturt, “ on our former journey found a channel such as now exists, elated with success, and ignorant of the dangers before us, we should most assuredly have rushed to inevitable destruction.” - (in the surf at the mouth).

·       What this confirms is that even before extraction of water upstream, river flows were highly variable with deep channels and strong flows replacing the shallow mudflats evident just a few years earlier.

·       Sim’s and Muller’s choice to interpret the high flow conditions of 1838 as the ‘normal’ situation and to imply that Sturt’s published comments support their thesis is itself evidence of the biased approach brought to the compilation of this document and interpretation of its data.

·       Even here the evidence does not support the view that the lakes were ‘always’ fresh before settlement – quite the contrary.

·       What the ‘A Fresh History ---’ document does indicate is that the extraction of significant amounts of water for upstream irrigation projects was a source of contention in South Australia from very early in the Colony’s history. Much of the collected data relates to this concern but has no relevance to the actual state of the river before settlement.

·       There is little doubt that at times of average or stronger flows the lakes would have been predominantly fresh, often for extended periods, but in times of low flow, without the moderating influence of upstream storage, off season flows would have been  too low to keep seawater out of the lakes and in times of extended drought, significant sea water intrusion would have been inevitable. The Sim/ Muller document provides no evidence to refute this 

·       To be quite clear, however, evidence for the alternative hypothesis, occasional sea water intrusion, should be considered.

·       Paleolimnologist, Professor Peter Gell, of Ballarat University, concluded from examination and analysis of micro biological evidence in dated core samples of sediments taken from the lake bed that  the Lower lakes are, “ --- freshwater lakes that have had, at least in part, a tidal history’,over the past 6,000 years.

·       John Schroeder, retired farmer from near Wongulla on the River Murray north of Walkers Flat, can show evidence now exposed, of varying low water levels in times past - (from red gum stumps, eroded cliff face and mud banks, and prolific river red gum generation on recently exposed soils), which show that the notion of consistently strong flows pre settlement are a fallacy and indicate clearly that the inevitable result of these low levels - sea water intrusion in the lower reaches - was a feature of the river system long before European interference.

·       The navigation difficulties for steamers on the Murray from the early 1850s prior to the regulating locks and barrages have been well documented and preceded the significant upstream extractions blamed by Sim and Muller for saltwater intrusions in the late 1800s.

·       In fact evidence included by Sim and Muller itself confirms low flows in the off season and in times of drought from the earliest times of settlement. And yet the Sim/Muller conclusion is that saltwater intrusions became an issue only in the late 1800s due to increasing extraction upstream.

·       Perhaps the most convincing evidence of all of the different nature of the Lower Lakes shoreline when compared with fresh water environments upstream is the complete absence of river red gums and/or any evidence of their past presence.

·       Whereas river red gums (Eucalyptus camaldulensis) are a feature of the Murray River and its back waters, Hattah lakes, Barmah forest, Ral Ral creek, and Chowilla to name just a few – and the fresh water tributaries which flow into the lakes, the Bremer, Angas and Finniss are marked by large river red gums along their banks – Lower Lakes shores are bare of such trees – (and yet they seed prolifically and there would have been no shortage of seed in the lakes).

·        Rather, the shores of the Lower Lakes resemble those around inland salt lakes with vegetation quite different from that flourishing in the freshwater habitats up stream and there is no evidence that it has ever been different. Aboriginal people from the Lower Lakes and Coorong came to the river red gums of the Finniss River and Currency creek and Bremer River to source their bark canoes. (See Photo 7 – canoe tree near the Bremer 3 km from the lake).


Photo 7

·       (See Photo  8 – sparse lakeside vegetation north of Milang compared with the banks of the nearby Bremer River (Photo 9) and prolific river red gum generation on newly exposed banks near Wongulla (Photo 10).)



 Photo 8                                            Photo 9                                            Photo 10

·       Regardless of the ideological preferences driving the compilation and conclusions of the Sim/Muller document, the estuarine nature of the Lower lakes is self evident and supported by valid scientific evidence.

·       “A Fresh History of the Lakes: Wellington to the Murray Mouth, 1800s to 1935” does not warrant the credibility claimed for it and the cost of glossy publication (and distribution) by government agencies cannot be justified.

·       It most certainly should not influence government policy in relation to the need for an imminent seawater solution to the current problems of wind blown erosion and deposition of acidic soils around the exposed bed of the Lower Lakes.

The seawater/fresh water estuarine mix – different but not dead.


“Saltwater will kill the lower lakes – it would be like letting off an atomic bomb”

This is the claim of a prominent member of an activist group based at Clayton Bay, but this same person has stated publicly (documented in his September 2008 submission to the Senate Subcommittee), “ --- to hell with critical human needs,” which perhaps puts his position in context at the radical end of the extreme.

In reality, a healthy estuarine environment would be a more natural and environmentally more desirable wet land habitat than the dry and desolate wasteland currently developing where the lakes once were.

Estuaries with varying levels of salinity are a natural aquatic environment, common where rivers meet the sea across the planet and with thriving ecosystems. Before the intervention of barrages, the Murray fed into just such an estuary – and when strong flows (floods) occurred the salinity was flushed out to sea.

If (when) strong flows return to the Murray system, the salinity will be flushed out.

If strong flows do not return, an estuarine environment is inevitable.

                                        - and better sooner rather than later.