Dam water on the way out for Perth

Written by Suellen Jerrard - 30 March 2009

Dams could stop supplying drinking water to Perth in as little as seven years and become obsolete in 50 years, under the Water Corporation’s planning scenarios, forcing a reliance on up to four expensive desalination plants and recycled wastewater.

From providing almost all drinking water for the integrated supply scheme in the 1970’s, the corporation predicts dams will provide about 28 per cent this year, 15 per cent by 2030 and be phased out by 2060.

“The worst case scenario, looking at the climate change predictions and what’s happening with stream flows, is that around 2015 you could end up with the odd year with no total run-off into our dams at all”, corporation chief executive Jim Gill said.

Dr Gill said the corporation was planning to replace surface water and meet demand for potable supplies of 470 gigalitres annually by 2060 with four desalination plants, recharging underground aquifers with recycled wastewater, continued use of ground water, industrial reuse and community-based schemes designed to cut consumption.

Dr Gill said the cost of water would continue to rise as more expensive sources replaced dams.

The corporation estimated surface and groundwater cost about 0.80¢ a kilolitre compared with $1.25kL for supplies form the State’s first desalination plant at Kwinana.

It estimated the average cost of the planned sources to 2060 at $1.70kL.

“The more we do desalination instead of something else the more water is going to cost.  But it’s not going to break the bank.  Water is very cheap today and it will still be very cheap”, Dr Gill said.

Conservation Council director Chris Tallentire said that the Water Corporation’s projections were poof water was not valued highly enough and people had to pay more for the precious resource.