By Tracy Sorensen
A world-scale environmental disaster is unfolding in Australian rivers, dams and reservoirs. Decades of pollution have combined with drought conditions to produce what is possibly the largest infestation of toxic blue-green algae ever recorded.
Toxins associated with the algae are believed to attack the human nervous and digestive systems, skin, and liver. In outback New South Wales, hundreds of sheep and cattle have died after drinking affected water. Country towns have switched to emergency water supply measures, while farmers in affected areas are buying tanks of fresh water or driving hundreds of kilometres daily for their families' requirements.
While government departments have swung into action to alleviate immediate problems, scientists and ecologists have warned that unless fundamental changes are made in agriculture, sewage treatment and river management, many of our rivers could die.
Attention is now focussed on a 1400 kilometre stretch of the Darling/Barwon river system between Mungindi on the Queensland border and Wilcannia in western NSW. Scientists and journalists flying over the area have reported that the water, normally a milky-tea shade, has turned a lurid emerald green.
It appears blue-green algae is a threat to the river system alive or dead. Alive, there is a 60-70% chance that it is toxic. But even if it is killed (spraying it with copper had been tried with some success, although this adds heavy metals to an already unhealthy soup), two more problems arise. The algae can release more toxins as it dies; and the decomposing mass begins to take oxygen from the water.
According to water experts, the Darling is under immediate threat of deoxygenation, of becoming an ecologically dead river in which fish and other plants and animals cannot live.
For many farmers plagued by debt, drought and recession, the algae has been the last straw. John Davis, a farmer whose property runs along the Darling, told ABC TV's 7.30 Report on November 28: "I've put up with floods all my life, I've put up with droughts all my life, but I don't think I can put up with this".
Spreading threat
The area under immediate threat from the algae, the Murray-Darling river basin, takes in about 10% of the land area of Australia, an area crucial to the country's agricultural output.
Other river systems showing signs of blue-green algae infestation include the Williams River, which supplies some of Newcastle's water; the Hawkesbury River on the outskirts of Sydney; the Murrumbidgee; the Condamine in Queensland and the Peel-Harvey inlet in Western Australia.
According to NSW Water Resources Department expert Brian Haisman, blue-green algae growths are nothing new: a growth, or bloom, was the 12th century. In Australia, the first recorded deaths of livestock as the result of an algal bloom occurred in 1878 at the mouth of the Murray River.
Algal blooms occur where several conditions coincide: adequate sunlight, dissolved nutrients (including phosphorous and nitrogen), warm temperatures and still water.
"It was here before European farming practices and European civilisation hit our country", Haisman told Â鶹´«Ã½, "but without the slightest doubt we have given it a substantial nudge along."
For the Darling River, that "nudge" has come in the form of excessive nutrients finding their way into water systems through a wide range of causes: from the run-off from nitrogen- and phosphorous-rich fertilisers, to the methods of sewage treatment in country towns; from livestock droppings at river's edge, to cars being washed with phosphorous-containing detergents. Riverbank erosion has increased sediment loads, which, when leached, release more nutrients.
At the same time, natural nutrient-absorbing elements within the river systems themselves have been wiped out. Clear-felling, for example, has eliminated nutrient-absorbing forests in some areas. Aquatic plants which used to soak up nitrogen and phosphorous were killed off when wetlands were transformed into crop lands or paddocks.
Meanwhile, the flow of the river has been slowed by increasing demands on water volume. Water is pumped to provide water for towns, homesteads, crops and pastures. Increased water flow during flooding traditionally gave the river system a chance to regenerate; more recently, any increased flow has been seen as a bonanza for all those with a pump station.
Two years of drought — producing warm, still conditions — have now combined with all these factors to produce disaster.
Cotton
Some observers, and some of the affected farmers, insist that there is one interest group whose use of the Darling/Barwon river system has disproportionately contributed to the mess: the rapidly expanding cotton industry of southern Queensland and northern NSW.
"The real problem is the agricultural run-off from the cotton industry", Simon Disney, of NSW Democrat MP Richard Jones' office, told Â鶹´«Ã½. In the industry, tail waters from the irrigation process are commonly retained for reuse: a laudable concept. But this retention has tended to concentrate the nutrients picked up from fertilisers, and run-off from the process has ended up back in the Darling.
Meanwhile, the cotton irrigation system is set for a major expansion: there are plans for an eight-fold increase in the capacity of the Pindari Dam on the Severn River east of Moree. This project would be subsidised by the cotton industry to the tune of about 60%. The NSW Nature Conservation Council has called for the project to be abandoned.
"It's hard to [say] how important the cotton industry is in removing water from the rivers which would normally flow down into the Darling, but certainly it's a consideration, a concern, something we have to think about", Dr Gary Jones, senior research scientist with the CSIRO Division of Water Resources, told Â鶹´«Ã½. "It's very difficult to point the finger at one industry or one part of the catchment and blame them totally.
"I think there's not going to be one simple solution, one simple thing to fix up all those things ... There's a political, a social question, of how much irrigation we believe is acceptable for our environment. We've given the right to irrigate. The question is, as a society, do we want them to maintain that right, or do we want to prevent the expansion of certain industries that use a lot of water and irrigation?"
Meanwhile, various government-sponsored committees have been gathering information about problems of excess nutrient content for some years now.
Control
Strategies for overcoming the problems include the regeneration (or re-creation) of wetlands, introducing nutrient-stripping sewage treatment systems for country towns on river systems, tougher policing of phosphorous pollution from feed lots, abattoirs, and other problem areas, and the creation of "green belts" alongside rivers.
According to Simon Disney, "farming practices are going to have to change fundamentally. We are going to have to get more into organic farming rather than using chemical fertilisers. The level of nitrogen in organic fertilisers is quite often down as low as 4-6%, so there's greater likelihood of nutrients being used by plants rather than simply running off into waterways."
But how this could be done when "we have many National Party ministers who don't even believe the greenhouse is a real phenomenon" was another matter.
In Britain, said Brian Haisman, government departments were experimenting with the notion of "exclusion or control zones, declaring nitrate sensitive zones, and beginning to control stocking rates". A farmer with 60 cows, for example, might be told to cut down to 40. "Their ministries are beginning to develop notions of compensation to aid people whose farming has to alter for the community good."
"Individual farmers can't be expected to do anything in isolation," said Gary Jones, "especially in tough economic times".
It appears there is no shortage of ideas; the question comes down to money and what the mainstream media call "political will." The situation in the Canberra sewage system might well serve as a symbol of current problems: apparently, there is an advanced tertiary treatment plant there which is able to biologically remove nitrogen and phosphorous to very low levels. But to cut costs, the system runs without its nitrogen facility. Some observers have commented that if the current disaster can be brought under control, it might be a blessing in disguise: an event to prompt new political and environmental decisions, and get money spent that ought to have been spent a long time ago.