2006 was Victoria's worst recorded year for rainfall, yielding only 165 gigalitres of inflow to Melbourne's catchments compared with the previous 10 years' average of 453 Gl. In a panic response, the government opted for what had previously been an option of last resort - a desalination plant.

The proposed plant will industrialise a wild and magnificent piece of Victoria's rural coastline only 90 minutes from Melbourne that is of such significance it is listed on the Register of National Estate.

The proposed desalination plant will produce 150 Gl water per year, upgradable to 200 Gl. Melbourne currently uses approximately 380 Gl per year. At present, 450 Gl of urban storm water and 150 Gl of treated waste water runs into Melbourne's bays and Bass Strait. Independent expert water authorities confirm that at least half of the storm water, and most of the treated water can be easily collected and reused, at less economic and environmental cost than the proposed water factory.

The Victorian government uses throw-away lines to justify its decision. In particular, the government repeats the mantra that Victoria needs a rainfall-independent water source and ignores the wealth of expert evidence that water supply can be secured using less environmentally and economically costly methods. The responsible, sustainable solutions include:
* Stop the rain water running off roofs, increase installation of rainwater tanks, and plumb these for use in toilets, laundries and on gardens. This can easily capture the volume of water that the desalination factory will produce, at 20% of the carbon cost (Marsden Jacobs, 2007).
* Stop the rain water running into the bays via Melbourne's drains by regional storm water capture and storage systems.
* Reduce consumption: Melbournians still use over 280 litres water per person per day, double what residents of south-east Queensland and much of Europe are using. Significant further improvements in water efficiency are possible with wider use of low-flow shower heads, low flush toilets, grey-water reuse systems and broader embracement of a general water saving mentality. Likewise, substantial savings in industry and from public buildings can be made through government (dis)incentives and upgrading of technologies such as that of old and thirsty cooling systems.       
* Use recycled water for industry and irrigation, rather than continuing with ocean outfalls. The Eastern Treatment Plant upgrade and Water Substitution project would recycle 135 Gl of water.
* Reduce infrastructure inefficiencies - currently 8% of Melbourne's water is lost through leakage according to an Australian Water Resources Assessment report.
* Stopping logging in Melbourne's Thomson and Yarra catchments would yield an extra 30 Gl per year.

Desalination and climate change

The desalination plant will require a massive 90 megawatts of power (120 MW if upgraded as proposed). In real terms that means one million tonnes of CO2 per year, equivalent to 280,000 new cars driving our roads.

Melbourne's current water delivery comes at a low energy cost due to the passive system of catchments and the use of gravity from the catchment dams to the points of use. According to the 2005-06 Victorian Water Review, Melbourne Water's average energy use for treatment and water delivery was 0.4 megajoule/kilolitre and the total urban weighted average across Victoria was 0.24 MJ/kL for 2005-06. In contrast the desalination plant's power consumption will be approximately 19 MJ/kL assuming it is powered by brown coal.

Ironically, it is global warming and air particulate pollution that are largely responsible for reducing rainfall projections.

The Victorian government argues that the desalination plant will be 'carbon neutral'. The current Victorian maximum wind power capacity is 134 MW. The desalination project will require 90-120 MW. To be true to federal emission reduction targets, all potentially available "green energy" should be used to satisfy current requirements, or for new demands that have no better alternatives. Desalination certainly does have preferable environmental and economical alternatives.

Using carbon trading or offset schemes to justify any project that may have more sustainable alternatives is against the spirit and intent of such schemes. The desalination plant will be financed and operated through a Public Private Partnership, essentially guaranteeing profits to a multinational company for years to come, with profits and costs including those of any necessary carbon credits to be paid by water consumers.

Marine ecosystems

In order to produce 150 Gl of water per year, the four-metre diameter ocean intake pipe will suck in approximately 14,000 litres of seawater every second, taking with it and killing approximately 300,000 planktonic organisms per second. The affected organisms are the base of the food chain for higher species, and are larval life stages of the species that colonise the ocean's reefs and provide for recreational and commercial fisheries. The dead organic mass will likely be deposited to landfill, contributing further to carbon emissions via its decomposition.

Seven thousand litres of effluent will be discharged back to the ocean every second. This will comprise biocides (e.g. chlorine) and other chemicals, heavy metals and concentrated brine.

Despite government claims to the contrary, the chosen site has poor mixing characteristics. Thus, despite mitigation efforts, salinity of the receiving waters will increase, and especially during periods of calm weather a proportion of the concentrated brine will sink and accumulate in protected holes and caverns that characterise the rocky ocean floor of the chosen site. The risk of a salty layer in and over the substrate is the negative effect on base food chain organisms and larvae of higher species via osmotic effects and via reduced oxygenation.

More information:
* Your Water Your Say <www.yourwateryoursay.org>
* WWF, "Making Water: Desalination - option or distraction for a thirsty world?", <www.panda.org/news_facts/newsroom/index.cfm?uNewsID=106660>.
* Marsden Jacobs Associates, April 2007, "The economics of rainwater tanks and alternative water supply options", report prepared for ACF, <www.acfonline.org.au/uploads/res/res_rainwater_tanks.pdf>.