Download Millennium Drought and Water Quality


Article for ‘Tatura Guardian’ newspaper.

Deadline Friday noon.

Proposed series of articles or opinion pieces laid out in letter format.

Series: ’In My View’

Author: Kevin Linton. Partner at consulting business ‘TopInfo’ based in the township of
Tatura that deals with Information and Troubleshooting for those that require it.

Article title: The Millennium Drought and Water Quality.
The Millennium Drought and Water Quality
The drought that lasted almost 12 years and was particularly bad in Northern Victoria has now
become known as the Millennium Drought.
Almost 100 years prior to this another drought of similar magnitude occurred in Australia. The
Millennium Drought lasted longer and had greater repercussions than the previous one but
unfortunately the 1898 drought is now beyond human memory and the community is reliant
upon written reports to indicate the conditions at that time.
This time around, there were water shortages in most towns and cities around Australia,
agricultural production all but ceased and many European and deciduous trees died from lack of
water.
Infrastructure in water saving technologies was boosted during this time in an effort to provide
towns and the environment with supply and a recognition developed that existing infrastructure
was in need of renewal too.
There was an increase in environmental awareness, pipelines were used to supply water to cities
and towns, desalination plants were built to supply potable supply to cities and environmental
concerns drove change. A Basin Plan (Plan) was commissioned to review environmental water
share, the Plan based on a large share for the environment was rejected and consultation and a
new draft Basin Plan now outlines a smaller environmental share but State governments have
failed to agree to support this draft.
State governments have failed to support the Plan and this can be summed up by three points:
1. South Australia (SA) believes there share is too small,
2. Victoria and New South Wales (NSW) believes the SA share is too big, and
3. Victoria believes some aspects of Victorian Water Law have not been taken into account
(ie. A component of Sustainable Diversion Limits, SDL).
The debate continues, but it centres essentially around two components; water volume and
quality. These aspects can be considered interlinked as a small volume of water that has a fixed
amount of contaminants makes the water quality poor (eg. salty). If we maintain the
contaminant level and increase the volume two or three fold (dilute it), the water quality is
probably considered to be good.
Another aspect of quality is potable water and environmental water is not dependent upon the
same criteria (eg faecal bacteria do not cause a problem in environmental water but has strict
limits in potable water).
Now bulk water that flows down the River Murray comes primarily from Victorian and NSW
rivers, while SA is dependent upon both quantity and quality from these upstream states.
The Basin Plan has concentrated on volume aspects of river flow to ensure sufficient river
health. The importance of a healthy river was brought into focus when in water short periods
blue-green algal blooms occurred and during the millennium drought the river mouth at the
entrance to the sea closed due to siltation and insufficient water flowing through.
This resulted in a number of consequences. Lake Alexandrina dried out and the ‘Coorong’
(Internationally registered wetland) in this system started to deteriorate. Firstly, as no fresh
water was entering the system (or rather, the evaporation rate was greater than the rate of fresh
water entry) salt levels increased in concentration and salinity became a bigger problem.
Eventually, most of the vegetated marsh land bordering the lake system dried out denying birds
and fish habitat.
A secondary problem became evident in some soil types where iron sulphates are found as
components of sediments. When these dry out a chemical reaction (known as reduction) occurs
and iron sulphates are converted to hydrogen sulphate (sulphuric acid). Unfortunately, this
reaction is essentially irreversible in this situation and the sediments and water become toxic.
Now, to the uninitiated this may not be a ‘big deal’. However, such acidity can sometimes reach
levels of pH 4-3 and this is enough to strip the skin from your hands in a few seconds, this
obviously, is a very serious situation.
As mentioned, this is irreversible and can sterilize the immediate environment. Only a water
supply will stop the process from continuing and dilute the sulphuric acid from causing harm.
Unfortunately salt (this includes Sodium Chloride or table salt, but also includes salts of
magnesium and Calcium, among others) are difficult to remove from water supply as these
compounds are soluble and mix completely in solution. Australia is blessed with fairly large
quantities of salt in its soils, particularly its subsoils where it has been washed (from harm’s
way) over millions of years. The problem with salt is it is deposited in root zones of crops when
water-tables rise and increases in concentration with evaporation. This causes soil sterilisation
and the salt is highly mobile.
The eventual destination of all mobile salt is the sea and the river network is how it is
transported there. The salt in the river system does not cause a problem when diluted (eg. during
floods concentrations are very low). This situation is actually taken advantage of in times of
high flow in the Murray to dispose of salt from irrigation areas thus keeping them productive.
The River Murray then is actually used as a drainage system as well as an irrigation network and
also a valuable environmental resource. This is a multiuse system depending on the
environmental conditions at the time and if managed correctly, can and has been, to every bodies
benefit.
The salt problem is definitely a water quality issue for downstream users, in particularly SA. Mr
Weatherill, Premier, SA has indicated they will go to the High Court to ensure larger volumes of
water for SA. “to keep the river healthy” and to “flush out the salt”. Unfortunately, Mr
Wheatherill seems to have missed the main point in the water quality argument and this is, about
80% of the salt in the Murray comes from SA sources (ie. enters the Murray within SA).
In my view, insisting on larger quantities of water from upstream states to dilute salt to
acceptable levels that comes from SA does not provide incentive to reduce salt from entering the
Murray in SA. This sounds like encouraging SA to ignore its problems and responsibilities to
reduce salt from entering the Murray within its borders. A simple analogy (if it succeeds in
maintaining maximum flows to its state) is like putting Dracula in charge of the blood bank and
only encourages more abuse.