Pipeline needed: There is consensus that it would devastate the ecology of these waterways to increase their use as drains. The preference of experts and environmentalists is likely to be a pipeline three metres in diameter and 20 kilometres long, through the Southern Highlands to Avon Dam. From Avon the water can be sent to Prospect Reservoir in Sydney.
Hydro a side-benefit: Such a tunnel could move 1500 million litres a day and generate hydro-electricity to offset up to 60 per cent of pumping costs and greenhouse emissions.
Increased flexibility: Ian Tanner, General Manager, Bulk Water, with the Sydney Catchment Authority said the proposed changes were not a response to the drought. “This proposal will assist in addressing unknown variables such as climate change,” he said. “The scientists are saying we are going to have more extreme events. This does add flexibility.”
Creek is "drowning": Since 2003, Doodles Folly Creek in the Southern Highlands has been drowning, despite the drought. For three years the torrent has roared with the sound of Sydney’s dams being topped up from the Shoalhaven.
An open drain: Using three pumping stations and a series of tunnels, water is now lifted from Tallowa Dam to the top of the Southern Highlands escarpment near Fitzroy Falls. From there, gravity takes over. When the Sydney Catchment Authority wants to fill the Upper Nepean Dam it simply releases the Tallowa water into Doudles Folly Creek. The stream becomes virtually a drain, and has carried hundreds of billions of litres towards the Nepean Dam in the past few years.
Wingecarribee also at risk: When Warragamba Dam is low, Wingecarribee River near Moss Vale is commandeered for use as a water expressway. This harms ecosystems and would not be ecologically sustainable if pumping was more frequent and involved greater volumes, Mr Tanner said.
Prolonged flows would cause long-term damage: A discussion paper on the problem says: “There would be longer-term impacts on plants and animals as a result of prolonged flows. Wetland areas would be flooded for longer periods, with the potential for long-term damage. Animals can be flushed away and habitats modified, making recolonisation difficult. Plant and animal pests such as carp are favoured by constant flows.”
Platypus threat: It adds that platypus burrows could be lost and vegetation swept away, making it harder for the monotremes to feed and breed in such fast-flowing streams.
The Sydney Morning Herald, 26/8/2006, p. 11