Shoring up our options

12 Mar 2007

Torrential downpours have filled the Darwin River Dam to capacity, while elsewhere across the nation towns and cities are struggling to provide their communities with an ongoing water supply.

Our overflowing dam and wet season rains give a false illusion of abundance.

The Darwin River Dam first began supplying water in 1972. At that time it was projected that the capacity would meet the needs of a 200,000-strong community. But already, with a population of 110,000 currently tapping into the supply, there is overwhelming doubt the Dam will meet the needs of another 90,000 people.

Significant stress on the supply is occurring with excessive water use. Darwin people use up to three times more water than people in other capital cities across Australia.

More than 70 per cent of water is used in our gardens. While wild wet weather overflows pools and floods gardens, watering systems are continuing to pour this precious resource down the drain.

``Basically, Darwin people have forgotten how scarce water can be up here,’’ Power and Water Corporations Water Services Manager Paul Heaton said.

``Up until the Darwin River Dam was built in the 1970s water was really scarce.

``Now we have been lulled into a false sense of security. Just four in 10 people in Darwin think water is a precious resource. But if our population keeps growing at its projected rate, our water supply with one dam will not be enough to sustain our community in 15 years time.’’

In a bid to sustain water supply for the Darwin community in the generations to come, the Power and Water Corporation is seeking to develop a range of strategies, from education to building future water supplies.

``In the first instance it is critical that our community supports water conservation,’’ Mr Heaton said.

``Our use and waste of water does affect our future – but many people are oblivious to that. Developing responsible habits towards sensible water use is obviously paramount.’’

Construction of additional water supplies are also under investigation.

A series of possible dam sites have been investigated by the Power and Water Corporation. Those possibilities have been whittled down to three future locations – at Marrakai, Warrai and Mount Bennet.

At each site there are a number of dam options, each of them more than three times the size of the Darwin River Dam.

``We are reviewing these options as well as some of the previous options,’’ Mr Heaton said.

``The earliest we are anticipating needing a new dam is in 15 years, but our first preference is that people think about our current water use.

``Building a new dam is a five year process which will cost hundreds of millions of taxpayer dollars. It’s an incredible burden – a cost largely related to complacency.’’

The organisation’s second preference is to develop intermediate options, which involve raising the dam and increasing ground water supplies. Raising the Darwin River Dam walls by 1.3 metres enables a 20 per cent increase in water supply.

``We have to protect our range of options,’’ Mr Heaton said.

``The work we are doing at the moment is about determining environmental, heritage and engineering issues of each site. Marrakai has the biggest catchment area. If we develop Marrakai we also have to develop a water treatment plant alongside that.

``Our goal at this point is to take all of the options forward. Diversity of supply is critical because we are not immune to climate change or drought conditions or a range of other impacts.

``We are all responsible for ensuring that we have adequate water for the future, and that we use it responsibly.’’

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