Logic evaporates in water solution

Water Minister Tim Holding recently leaked part of a report that his department had commissioned to update the cost of building new dams.

For a dam on the Mitchell, the previous $1 billion price tag was revised to $1.35 billion.

Having used the taxpayer funded report for political purposes, the government has refused to make it public.  All we have is the Minister's word that the report proved that dams are a bad option.

Bad for whom?

Earlier this year I undertook comparison of the different approaches to augmenting Melbourne's water supply.  The $1.35 billion capital cost update allows this to be revised.

Aside from a new dam, the alternatives for the water supply fall into four categories:

• FORCING consumers and industry to use less;
• RECYCLING water largely through treating sewage;
• SAVING water from the northern irrigation areas and piping it south; or
• BUILDING a desalination facility.

Forcing consumers and industry to use less water was the policy failure most closely associated with the former deputy premier John Thwaites.  Its shortcomings were exposed by the drought and the punitive water restrictions this has required.

The failure of Thwaites's policy forced the government to face reality and seek out new bulk water supplies.  This will be the first addition to existing sources in two decades, during which time the city's population grew 25 per cent.

Supplementing new bulk supply sources are regulations requiring backyard tanks, which provide an unreliable water supply at an extremely high cost.

Of the new supply options, recycling water turns out to be very expensive.  This is because it would be unacceptable to use the recycled water for human consumption.

Confining such water to garden and other non-drinking applications therefore requires a duplicated local pipe system.

Saving water by plugging leaks in the northern irrigation region and piping it south is the option the government is pursuing through the Sugarloaf pipeline scheme.

But, based on experience in other basins, the government is overestimating the water that will be saved.  This is causing considerable opposition from irrigators who envisage outcomes of forced sales and less water for farm use.

The government has put the capital outlay of its other strategy, the Wonthaggi desalination plant, at $3.1 billion.  And the facility's price tag involves building new pipelines and energy for its operations.

The following are the costs of the different options (per kilolitre):

• A new dam on the Mitchell:  67
• Eastern Treatment Plant recycling:  242
• The Sugarloaf scheme:  166
• The Wonthaggi Desal. plant:  301

An even cheaper option than a dam on the Mitchell would be one on the Macalister linked into the existing Thomson Dam.  In both cases the Gippsland solution provides a bonus of improved irrigation security and flood control for Gippsland towns.

Government ministers know that the best policy is a new dam.  They have whole departments to do the arithmetic for them.

Unfortunately, they have abandoned promotion of public interest to appease noisy interest groups, especially green activists who are opposed to any developments.

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