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Received evidence for deterioration in water quality in the River Murray

By Jennifer Marohasy - posted Wednesday, 20 August 2003

Facts do not cease to exist because they are ignored.
- Aldous Huxley

Although it is rare for both sides of federal politics to agree the Government and Opposition agree that saving the River Murray is a national priority and both have canvassed the possibility of taking water from irrigators to increase environmental flows - in the case of the Opposition 1,500 gigalitre.

Why such drastic action? The river is apparently very sick. What is wrong with it? According to the Wentworth Group's Blueprint for a Living Continent (pdf, 208kb), The Economist agazine, and everyone in Ticky Fullerton's book Watershed, including Ticky Fullerton, deteriorating water quality is a major problem - in particular worsening salinity.


The CSIRO website includes the statement, "…Australia's largest and most developed river system, the Murray-Darling Basin shows the nature of the problem we face. Salt levels are rising in almost all of the Basin's rivers and now exceed WHO guidelines for drinking water in many areas. Business as usual is not an option. If we do nothing, the salinity of the Lower River Murray - where Adelaide pumps out its drinking water - will eventually rise to exceed WHO guidelines."

But the facts do not support these claims of deteriorating water quality.

Key water quality indicators include turbidity (a measure of sediment load), nitrogen and phosphorus (nutrient levels) and electrical conductivity (saltiness). According to the Australian Water Resources Assessment 2000 we spend $142- $168 million each year on water quality monitoring. So let us consider the water quality data for key sites in the River Murray.

Salinity Levels

While Ticky Fullerton's 354 page book laments deteriorating water quality, no water quality data is provided. There was no data to accompany the very powerful statement on the CSIRO website. There is no current information on water quality trends for key sites on the CSIRO or Murray Darling Basin Commission (MDBC) websites.

Daily readings for salinity from 1938 are available on request from the MDBC for Morgan, South Australia. Morgan is the key indicator locality for water quality in the Murray Darling Basin. Morgan is just upstream of the pipeline off-takes for Adelaide's water supply. Its use as an indicator site emphasizes the relative importance of river salinity impacts on all water users in the system.

When the yearly averages for salinity measured in EC units for Morgan are plotted, current salinity levels at Morgan are equivalent to pre World War 2 levels! A plot of salinity levels for just the last 20 years suggests salinity levels are dropping at this key indicator site. These figures indicate that water quality is improving!


The MDBC also provided me with salinity levels at Swan Hill or Yarrawonga, and there is no increase in salinity for the years 1982 - 2002.

The CSIRO website reads, "Salt levels are rising in almost all of the Basin's rivers and now exceed WHO guidelines for drinking water in many areas… If we do nothing, the salinity of the Lower River Murray - where Adelaide pumps out its drinking water - will eventually rise to exceed WHO guidelines."

WHO guideline levels are 800 ECs. Salinity levels are not approaching 800 ECs at key sites in NSW and Victoria. Salinity levels are not increasing at key sites in NSW and Victoria. Salinity levels are dropping at the key site in the Murray Darling Basin, Morgan. Salinity levels are high in the lower reaches of the river and only exceed WHO guide levels near the river mouth as you might expect. Someone is misleading the Australian public!

I queried my findings directly with the MDBC. In response, Dr Pradeep Sharma, Senior Modelling Engineer, replied, "Thanks to major investments in salinity mitigation works undertaken in the Murray Darling Basin over the last decade, I would like to concur with the conclusion that average salinity in the River Murray has in effect improved during the last decade."


Turbidity is a measure of the suspended sediment load. Turbidity levels generally rise with increased discharge (eg. increased rainfall). Australia's inland river systems are considered to be naturally relatively turbid.

Since European settlement the most significant change to water quality in many inland river systems is thought to be an increased sediment input from the early years of land clearing and the introduction of sheep, cattle and rabbits. As a result of improved management practices over recent decades erosion is likely to have stabilized or reduced to pre-European levels.

According to plots from data sourced directly from the MDBC, turbidity levels (NTU) at both Morgan and Swan Hill appear to be relatively stable. Turbidity has been measured at both sites since 1978. Average yearly turbidity levels have not increased over this period.

Mean daily turbidity levels at Morgan exceeded 400 nephelometric turbidity units (NTU) in July 1983 but the relatively high turbidity levels may have been a consequence of drought breaking rains carrying higher than usual sediment loads because of increased erosion from reduced vegetation cover as a consequence of the drought in the early 1980s.

During years of low mean turbidity, mean daily values for both Morgan and Swan Hill are typically in the 20 - 40 NTU range.

Nitrogen and Phosphorus

It is generally believed that algal blooms in inland rivers are due to elevated nutrient levels, particularly phosphorus. While it was thought that the major sources of these nutrients was agricultural fertilisers, sewerage treatment plants and feedlots, the most recent and relevant
report on the MDBC website suggested that a large proportion of the phosphorus may come from natural sources in particular basalt-derived soil.

Whatever the origin of the phosphorus, a plot of yearly average phosphorus levels (mg/l) for key sites in the middle and lower basin show levels have been stable since data was first collected in 1978 (data sourced directly from the MDBC).

High nitrate levels can be an indication of excess runoff from agricultural fertilisers. Nitrate levels also appear to be stable for key sites, at least since levels were first measured by the MDBC in 1978.

In Conclusion

On 16th July 2003 the Australian newspaper published some hard data showing actual water quality trends for the Murray River. The article was titled "Murray salinity tipped to rise", yet began "salinity levels in the Murray River have been halved since 1982" and the graph showing declining salt levels at Morgan did not accord with the title of the story. The journalist, Richard Sproull, was quoting from Matthew Kendall, of the MDBC, who was apparently quoting from a 1999 drainage strategy report when he said that he was expecting salinity levels to rise.

According to the reports on the website, this has been the prediction since at least 1998 - and it has been consistently proven wrong. Perhaps the computer models need an overhaul? Salinity levels at Morgan are now at pre World War II levels.

We have spent billions of dollars over the last 2 decades on environmental programs; it should not be surprising that the condition of our rivers is improving.

Large quantities of salt have always entered the Murray River from seepage of saline groundwater. The largest increases are usually noticed during low flow periods, for example during drought. Given the current extended drought across the basin the low salt reading at Morgan is even more remarkable. Why isn't this good news being reported?

On the basis of the received evidence, instead of revering our expert environmentalists and vilifying our farming communities, we could take a lead from Bob Carter who in his letter to the Editor of the Australian on 17th July 2003 (in response to the story of 16th) wrote, "That Murray River water quality is continuously improving, as shown by a halving of salinity content at Morgan since 1982, is about the best environmental news that Australians could have wished for. It is also a tribute to the many land owners and managers who have modified their land use practices towards just such an end. A better treatment for such good news would have been a full front-page article with the banner headline "Murray River Saved"".

It will be a travesty of justice if a single Murray irrigator should lose water allocation on the basis of the misinformation currently being promulgated by high profile scientists from our most respected research institution.

To quote Greg Easterbrook:

The Western World today is on the verge of the greatest ecological renewal that humankind has known, perhaps the greatest that the Earth has known. Environmentalists deserve the credit for this remarkable turn of events. Yet our political and cultural institutions continue to read from a script of instant doomsday. Environmentalists, who are surely on the right side of history, are increasingly on the wrong side of the present, risking their credibility by proclaiming emergencies that do not exist.

I would go further, and suggest we have institutional failure of the highest order when both sides of politics eagerly signup to a myth promulgated by our most respected research institution, the CSIRO.

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Article edited by Ian Spooner.
If you'd like to be a volunteer editor too, click here.

This article was first published at the IPA Water Forum No. 2, Canberra, 25 July 2003. Click here for the full text with graphs.

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About the Author

Jennifer Marohasy is a senior fellow with the Institute for Public Affairs.

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