Water quality concerns plague Queensland
AN UNPRECEDENTED 7.5 MILLION tonnes of water is estimated to have fallen onto southeast Queensland in this week’s super storm, stretching infrastructure to the absolute limit.
From the microscopic (E.coli in Warra) to the bizarre (sharks in Goodna), floodwater contains a potentially dangerous cocktail of unusual contaminants and foreign bodies – and it is not just humans who are at risk.
Sewerage systems are designed to handle four or five times their normal flow and whilst “treatment plants can cope with floodwater well,” Associate Professor Larelle Fabbro from Central Queensland University (CQU) in Rockhampton told Australian Geographic. “The main problem is if you get sewage or contaminated water feeding into the treated system.”
In Toowoomba, 120 km west of Brisbane, residents are being advised to boil water. Similar advice is being given to residents of Chinchilla and Warra, 300 km west of Brisbane, where E.coli outbreaks are reported.
Damaged water treatment plants mean that drinking water is being trucked into the several towns in the Lockyer Valley including Helidon and Gatton, 100 km west of Brisbane, where there is currently no available fresh water.
Volunteers pick through the matted debris at Sandgate
Contaminated floodwater
Lisa Bricknell, lecturer in environmental health at CQU, says contaminated floodwater poses real threats. “In a time of flood I would not normally be concerned about drinking water, the authorities are usually right on top of it. But I’d be more worried about floodwater,” she says.
Sharks have been spotted swimming in the main street of Goodna, 20 km south west of Brisbane and crocodiles are a risk northern Queensland. Less sensational, however, are microbes and fungi, which are predicted to contaminate much floodwater.
“Microbial contamination could include Cryptosporidium parvum and Giardia lamblia,” Lisa says. “The big worry is diarrhoea, particularly in uncontrolled floodwater.” Other than avoiding entering floodwater, taking care to wash hands and implements is a wise precaution.
Other flood-related health hazards
The risk of mosquito-borne diseases are the next concern. “At this time of the year you usually see a spike in cases of Ross River and Barmah Forest viruses. This year, because areas of standing water are so widespread, we’ll see more areas for mosquito breeding which will probably mean in increase in reported cases of mosquito-borne diseases,” Lisa says. “Be vigilant”, she recommends, “and use plenty of insect repellent.” More serious diseases such as cholera are “so remote, it’s not something we need to worry about”, she adds.
Industrial effluent and runoff are unlikely to cause major health hazards, according to Mark Pascoe, CEO of Brisbane-based International WaterCenter. “There could be issues with contamination, but in this case there is so much water that we cannot measure the impact of, for example, a leaky fuel tank.”
It may take several months until water treatment and quality return to usual levels says CQU’s Larelle. “It depends on weather more than anything else. As floods recede, you’re normally looking at a couple of months until things are completely back to normal.”
Tonnes of sediment picked up by the flooding has become problematic to remove from water treatment plants. “The key issue is it’s very turbid water,” says Dan Spiller, director of operations for SEQ Water Grid Manager. “There are some issues in terms of water treatment, [such as] limiting production of water treatment.”
Flood water a threat to the ecosystem
Natural as it may be, mud in such vast quantities will alter the ocean’s water quality. “We have more sediment going into Moreton Bay than we would like. This is a huge flood; it’s not a normal sediment load” says Mark. “Iconic species like the dugong and sea turtle depend on sea grass. Sediment blankets seagrass and kills it.”
Though spillways are designed to minimise sediment flow, a flood like this will not stop the deluge of material flowing down the river. Aside from sediment, larger items from twigs to pontoons are filling Moreton Bay, damaging the ecosystem.
In northern Queensland, sediment entering the sea combined with an influx of non-saline water both pose threats to coral reefs, which can take generations to bounce back.
But floodwater sediment can be a natural blessing to an ecosystem. “What happens is that you’re moving sediment from the upper parts to the lower parts [of a river system],” says hydrologist Dr Barry Croke from the Fenner School of Environment and Society at ANU. “A fair amount will be deposited in the floodplain areas and builds them up with good soil. The impact of that can be positive because it introduces new nutrient to permit new plant growth.”
Still, Mark remains cautiously optimistic. “We’ve got a good handle on the management of the region. I’m positive, but this will not be a good year in terms of our guardianship of the environment.”
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