Article: Blue-green algae outbreak on the Darling River, 1991-92

Blue-green algae outbreak on the Darling River, 1991-92

After the 1990 floods across eastern Australia, there came a series of dry months, causing low river flows. Warm, shallow, slow flowing water created perfect conditions for algae to bloom and, by the beginning of October 1991, blue-green algae began to take hold in the Darling River in New South Wales. By summer, the algae had grown to cover an astonishing 1200 km of the Darling River – a frightful world record for Australia.

We don’t want to alarm people... but the toxin from blue-green algae is, in fact, in pure form more dangerous than cyanide.

On 5 November 1991, Bourke Shire President Wally Mitchell took to the radio to warn residents about the dangers of the bloom.
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Sheep and cattle began dropping dead from drinking the water. People living along the river were warned not to touch or drink the water for fear of severe eye and skin irritations, and ‘horrendous internal injuries’.

The New South Wales government declared a state of emergency and the Commonwealth government rushed to mobilise the army to provide aid to affected towns.

Our river is a mess. Over recent years the deterioration of the quality and quantity along the unregulated section of the Darling River has increased significantly ... We believe the philosophy that the stored water in the dams at the headwaters of the Darling-Barwon system belongs totally to the irrigation valleys around these dams is so wrong as to border on severe breach of human rights.

The condition of the Darling River that summer prompted the Wilcannia branch of the National Party to write an open letter pleading for water reform.

The immense outbreak of blue-green algae was attributed to low flows and increased nutrient levels in waterways – primarily a result of human activities – a process called anthropogenic eutrophication

The surplus nutrients are largely the result of man’s activity. We disturb the soil, allowing run-off to add nutrients to the drainage system; we discharge sewage effluent, and raise large numbers of stock, as well as fertilizing the soil for our crops, and the drainage from these activities flows into our waterways

Valerie May, Australia’s first fulltime freshwater phycologist, urging protection of waterways in the early 1980s.
Valerie May 1940s

The algal bloom on the Darling River made headlines around the world. The idea of a ‘toxic river’ captured the public’s attention. Australian farmer and writer Eric Rolls described the ‘flaring green ribbon’ as a ‘distress signal’, a plea from the heart of our rivers and soils.

The symbolic effect was significant. For many Australians it signified years of neglect towards our inland river systems, and added a sense of urgency to the water reforms already underway.

The problem has taken decades to get to this stage, and it may possibly take decades to overcome it.

Ian Causley, Minister for Natural Resources in the New South Wales Liberal-National Government, in December 1991, responding to questions about how the government could solve problems with the river systems.

Health metaphors became part of environmental consciousness and understanding: the rivers were ‘sick’ or ‘dying’. Letters to the editor suggested ‘we’re all to blame’.

The Darling has suffered what amounts to a massive heart attack.

Ian Smails, Chief Scientist at Department of Water Resources, from his address to a special blue-green algae taskforce November 1991.

The introduction of the Cap on water diversion

The pleas from the public in response to the blue-green algae bloom highlighted the broader issue of the deteriorating condition of the Basin’s river systems.

No-one has ever considered the health of the river as primary importance; it has always been getting water out and growing crops. Now it has got to the stage where we have to consider the river and its health.

No-one has ever considered the health of the river as primary importance; it has always been getting water out and growing crops. Now it has got to the stage where we have to consider the river and its healthAs part of water reforms already underway, John Klunder, a South Australian member of the Murray–Darling Basin Ministerial Council, argued in 1993 that there should be no further diversions. He warned of the potential for existing unused water entitlements in the Basin to be ‘activated’ and increase the amount of water extracted from the river.

The Murray–Darling Basin Commission ordered an audit of water use in the Basin, which was completed in 1995. The states were shocked by the findings. Median annual flows through the Murray Mouth were only 21-28 % of what they would have been in natural conditions. Instead of droughts occurring five times every hundred years, water extraction was driving the lower reaches of the Murray into drought conditions six years out of ten. In most years, more water was approved for extraction than was physically available in the rivers.

In 1995, the Commonwealth, New South Wales, Victorian and South Australian Governments unanimously agreed to a ‘cap’ on water diverted from the Basin for consumptive uses. Its purpose was to limit the amount of new entitlements available to extract water, while allowing entitlement holders to adjust the amount of water they could withdraw through ensuring efficient water use and water trading. The cap worked on a formula that took into account wetter and drier seasons, and after being tested for two years, became permanent in 1997.

In 1995, the Commonwealth, New South Wales, Victorian and South Australian Governments unanimously agreed to a ‘cap’ on water diverted from the Basin for consumptive uses. Its purpose was to limit the amount of new entitlements available to extract water, while allowing entitlement holders to adjust the amount of water they could withdraw through ensuring efficient water use and water trading. The cap worked on a formula that took into account wetter and drier seasons, and after being tested for two years, became permanent in 1997.

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Algae blooms in 2010 on the Lodden River, Middle Lake. Arthur Mostead/MDBA

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Gum Swamp Sanctuary near Forbes, New South Wales infested with blue green algae growth in March, 2003. Arthur Mostead/MDBA

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Blue-green Algae bloom at junction of Murray and Darling Rivers in 2010. IOJ Aerial Photography/MDBA

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Algae Colignan 1992. Credit: MDBA

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Darling River with Mt Gundabooka National Park, NSW towards the horizon in 2015. Josh Smith/MDBA

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