South East Queensland weather is nothing if unpredictable. After several abundant wet seasons, the region's dams are almost full; but in 2005 South East Queensland (SEQ) was in the grip of the worst drought in the state's recorded history, with the previous six year's rainfall well below average. At the same time, the region continued to experience the fastest population growth in the country, placing an unprecedented demand on the already dwindling water supplies. In 2006, as dam levels continued to fall, the Queensland Government passed emergency legislation to fast track the South East Queensland Water Grid ñ the largest urban drought response in Australia.

WaterSecure is the Queensland Government authority responsible for producing new, pure sources of water for SEQ through the Gold Coast Desalination Plant and Western Corridor Recycled Water Scheme. Purified and desalinated water are pure, safe, climate-resilient sources that will ensure water security for the region, as well as helping to sustain economic and population growth, and reducing environmental impact on our waterways.

The supply network includes more than 200 kilometres of large-diameter underground pipeline, three advanced water treatment plants and a reverse osmosis desalination plant. Combined, the schemes have the capacity to supply up to 365 megalitres of water a day to the South East Queensland Water Grid, industry and agriculture that's equivalent to the water usage needs of more than 1.8 million people under Target 200.

The $2.5 billion Western Corridor Recycled Water Scheme is the largest water recycling scheme to be constructed in Australia and one of the largest advanced water treatment projects in the world. Taking water that would otherwise have been discharged in to the Brisbane or Bremer River, the plants purify it to higher than drinking water quality to create a less climate-dependent water source for the region.

The scheme includes more than 200 kilometres of pipeline and three advanced water treatment plants at Bundamba, Gibson Island and Luggage Point. It has the capacity to provide up to 232 megalitres of water a day to the region's supply. The advanced water treatment plants use worldclass advanced water treatment technology incorporating microfiltration, reverse osmosis, advanced oxidation, remineralisation and chlorination to purify water.

The Western Corridor Scheme provides water to power stations and in the future will supply industry and agriculture. If the combined level of the dams in South East Queensland falls below 40 per cent (the trigger point determined by the Queensland Government), water from the scheme will be used to supplement drinking supplies. The scheme began supplying water in August 2007 ñ when dam levels reached their lowest point at just 16.8 per cent ñ significantly easing pressures on drinking water supplies at the height of the drought and to date has supplied more than 34 billion litres of water.

The scheme is also improving the health of our waterways and the environmentally significant Moreton Bay by reducing the amount of nutrients that would otherwise have been released into rivers. Across the scheme a phosphorus reduction of 90 per cent has been achieved and a 35 per cent reduction in nitrogen at the Bundamba plant, with the potential to increase this to 50 per cent across the scheme. In 2009, WaterSecure received the Healthy Waterways Industry Award for the Western Corridor Schemeís nutrient reduction program.

WaterSecure recently strengthened its commitment to improving waterways by supporting the Bremer River Forum, an event that brought together government, industry, academia, environmentalists and the community to discuss problems and solutions for the river, and decide on actions that need to be taken. In addition, WaterSecure also provided funding to the Bremer River Fund Appeal, which funds restoration and improvement works for the Bremer River and surrounding catchments.

The WCRW Scheme has been acknowledged globally as a leader in both water recycling technology and urban water planning, setting the benchmark for future projects in Australia and overseas.

The $1.2 billion Gold Coast Desalination Plant ñ the first large-scale plant on the eastern seaboard ñ is providing a safe, climate-independent source of water for South East Queensland. Located at Tugun at the southern end of the Gold Coast, the plant is able to supply up to 133 megalitres of water each day to homes and businesses on the Gold Coast and across Brisbane, and has supplied more than 27.5 billion litres since February 2009.

Desalination produces safe drinking water by removing dissolved salts and other minerals from seawater through a high level of filtration. The heart of the desalination process is reverse osmosis, the most popular type of desalination used throughout the world. The desalination process also involves pre-treatment filtration, remineralisation and chlorination. Water from the Gold Coast Desalination Plant is also fluoridated to bring it in line with the drinking water supply.

Desalination can be a highly energy intensive process, but modern plants use advanced technology and energy saving devices which result in them being far less energy intensive than traditional plants. The Tugun plant's energy consumption is better than expected, resulting in significant carbon dioxide reductions a year, further reducing its carbon footprint as well as energy costs. WaterSecure has also purchased Renewable Energy Certificates to fully offset the plant's energy use and combined with the use of energy saving devices which recover up to 97 per cent of the unused energy from the brine the Gold Coast plant is one of the best performers in terms of energy for desalination plants worldwide.

As well as the 12 buildings on site, the plant includes inlet and outlet tunnels that stretch more than a kilometre out to sea and sit on the ocean floor. Water flows through the inlet tunnel to the plant under gravity with a lower current than the surrounding ocean, ensuring fish and marine life are not sucked into the tunnel. The outlet structure releases brine into the ocean through 14 diffusers nozzles along a 200 metre outlet that disperses and mixes the water back into the ocean.

Since they were constructed in 2008, the marine inlet and outlet structures have become artificial reefs and home to thousands of fish, as well as marine plants, small marine animals and soft corals. Small plants and animals that live on the ocean floor are key indicators of a healthy environment because they are longterm residents, rather than moving in and out as more mobile organisms as fish do. Results from marine monitoring show these small plants and animals to be thriving on and around the marine structures.

When Channel 9's Paul Burt dived there last year, he said: The amount of fish congregating in that area is simply amazing! There's thousands upon thousands of fish from bait fish up to big kingfish and I even saw some big groper, tailor, bream, the list goes on. It's full of life; there's even soft corals down there.î

The Gold Coast Desalination Plant and Western Corridor Recycled Water Scheme are integral components of the South East Queensland Water Grid ñ the largest urban drought response in Australia.

The South East Queensland Water Grid is an integrated water supply system that secures and efficiently manages the region's water supplies. The Water Grid is diversifying SEQís water sources and allows the coordinated use of all major bulk water sources in the region through a network of pipelines that allows water to be moved from areas of abundance to areas that face a shortfall. The Water Grid includes dams and other natural storages, the desalination plant, three advanced water treatment plants and more than 450 kilometres of pipeline.

Four entities make up the Water Grid & WaterSecure, LinkWater, Seqwater and the Water Grid Manager. LinkWater manages, operates and maintains the Grid's potable bulk water pipeline network and related infrastructures, moving an average of 600 million litres. Seqwater provides catchment management and bulk water storage and treatment services, as well as owning and operating the regions dams and water treatment plants. The Water Grid Manager manages the operation of the Water Grid to ensure water security and quality in a cost effective way. The Grid Manager also holds the urban water entitlements for SEQ and purchases services to store, treat, produce and transport bulk water from the other three entities to sell to councils, power stations, agricultural users and other industrial users.

As part of the South East Queensland Water Grid, WaterSecure is helping to ensure a secure supply of water for the region now and in the future, as well as helping to maintain the regionís economic prosperity and lifestyle.

For more information about WaterSecure and the desalination and purification processes, visit their website at www.watersecure.com.au.