Central Queensland’s sub-tropical climate is not the place for a mega dam, a Rockhampton water infrastructure forum heard last week.
Water quality expert from CQUniversity Associate Professor Larelle Fabbro presented at the Fitzroy Water Workshop forum organised by central Queensland federal MPs Michelle Landry and Ken O’Dowd and Senator Matt Canavan.
Northern Australia Minister Josh Frydenberg was amongst 160 graziers, scientists and water experts to discuss the proposed Eden Bann, Rookwood Weirs and mega dam The Gap near Rockhampton.
Dr Fabbro said that unlike the tropics, in this region the water column did not mix completely as often and tended to sit in layers, especially in the dry season, with the temperature at the top layer being much higher than at the bottom.
“As the water sits for longer and longer periods of time the top layers have oxygen in them, and in the bottom layers the oxygen decreases,” she said.
The chemistry of the water changes and results in compounds such as ammonia and hydrogen sulphide being released when no oxygen remains. More toxic forms of various contaminants are produced.
“Once you have that stratification and those layers, they provide the perfect growth conditions for blue green algae,” Dr Fabbro said.
With big dams, such as the proposed Gap dam, water is held for longer and not flushed out or the water column mixed as frequently as in the smaller dams such as Eden Bann and Rookwood Weirs.
“My main concern is that more people in central Queensland think you can store water in dams and the quality doesn’t change.
“The longer water is retained, the greater the possibility of reduction in quality.”
Dr Fabbro said water was needed, but water quality also had to be taken into account.
“What we know is that Cylindrospermopsis, a type of blue-green algae, is present in central Queensland and large dams and layered water columns provide excellent growing conditions for this organism.
“If people or animals drink untreated water and are exposed to the toxin it produces, there is not always an immediate hit…It may cause long-term damage to your genes, kidneys or liver.”
Dr Fabbro said the Fitzroy River had been studied intensely since the 1970s and there was a large body of work on water quality published in peer-reviewed scientific journals.
The estimated $400 million Eden Bann and Rookwood Weirs are currently at the EIS stage and the only dams in the region that are shovel ready.
Meanwhile, a group of Rockhampton business people, led by Dominic Doblo, are pushing for federal government investment in The Gap, a $4 billion, 2 million megalitre dam that would be 20 times the size of Sydney Harbour.
Ms Landry said it would take at least 10 years for mega dam to be developed, while Eden Bann and Rookwood could be built in as little as two.
“What [the presenters] thought was The Gap would take up too much grazing and farmland, and the foundations would not support that much water,” Ms Landry said.
“And if we did have a flood, Rocky was liable to be flooded off the map.”
The forum resolved many issues and brought some to the surface, and a business plan was now being put together for different funding options for the two smaller dams, she added.
Ms Landry and Mr Frydenberg were also backing the Adani coal mine at Carmichael about 166km from Clermont to boost jobs and economic growth. They met recently with Adani in Canberra.
