Alternative water: Northern South Australia

Over the years several schemes have been proposed to use and move water to and from the north of South Australia. These proposals generally require desalination plants, large storages, very long pipelines, multiple pumping stations and significant power supplies.

Unlike gas and electricity, transporting water over long distances is significantly more complicated. Water is very heavy. A litre of water weighs a kilogram and considerable energy is required to move water along long-distance pipelines, in contrast to the far lighter commodities of gas and electricity, which are much cheaper to pipe similar distances.

Kati Thanda - Lake Eyre

The Lake Eyre Basin covers one sixth of the Australian continent. The basin is one of the world’s last unregulated wild flowing river systems, holding some of the rarest, least exploited ecosystems on the planet. The catchment terminates at Kati Thanda – Lake Eyre which was considered permanently dry by Europeans until the first recorded filling in 1949.

Kati Thanda – Lake Eyre and the surrounding lands are of profound significance to Arabana and Dieri people. Knowledge of land management practices that maintain the health of Country is passed on through generations, ensuring the land can continue to flourish. The physical and spiritual landscapes of these parks remain interconnected and inseparable from the physical and spiritual health of the traditional owners.

Kati Thanda – Lake Eyre is 15.2 meters below sea level and experiences the lowest rainfall in Australia of 100mm annually. The extreme arid conditions of Kati Thanda – Lake Eyre have created an ecological niche of adapted flora and fauna, many of which cannot be found anywhere else. During major flood events, the network of creeks and lakes in northern South Australia come to life, stimulating large scale breeding events for fish, invertebrates and waterbirds. All species, some of which are rare or threatened, rely on these events. The arrival of floodwaters not only sustains the land – it is also one of the world’s most impressive natural events and attracts visitors from all over the world.

Piping fresh water from Kati Thanda - Lake Eyre

Kati Thanda-Lake Eyre is normally dry and has filled to capacity only three times in the past 160 years, so it is not a reliable source of water. When in flood, the water does not stay fresh for very long as the 20 – 45 centimetres of salt crust on the surface of the lake dissolves over the period of the flood. When the lake is full, it has the same salinity as seawater but becomes hypersaline as the lake dries up and the water evaporates.

Desalination, a process that involves filtering out salt and bacteria from the water would be required to produce safe drinking water. However, as salt concentration is proportional to the amount of pressure needed to desalinate, hypersaline solutions require prohibitive pressures and so desalination would not be feasible for more than a few months when Kati Thanda-Lake Eyre fills.

Connecting Kati Thanda - Lake Eyre to the sea

Since 1883, many proposals have been made to flood Kati Thanda – Lake Eyre with seawater brought to the lake via canals or pipeline. These proposals served to develop permanent inland waterway beachfronts for home and tourist purposes, hydropower generation, a secure naval facility, transport, aquaculture and farming opportunities as well as the possibility of increased rainfall for agriculture to the east of the lake.

Due to the basin's low elevation below sea level, transporting water to the lake would involve raising the water up to 150 metres above sea level. The region's high annual evaporation rate (between 2,500 and 3,500 millimetres per annum) means that it is likely that accumulation of salt deposits would rapidly block any engineered channel.

In 2004, researchers from the Bureau of Meteorology and CSIRO assessed the likely impact of large permanent inland water surfaces on Australian rainfall and determined that there is no evidence that large-scale permanent water surfaces in inland Australia would result in widespread climate amelioration^[1].

The claims of extra rainfall from flooding Kati Thanda – Lake Eyre are questionable, while the impacts on internationally significant environmental and cultural values and the financial burden of building and maintaining canals, pipes and desalination plants is significant.

Great Artesian Basin

The Great Artesian Basin (GAB) is one of the largest underground freshwater resources in the world. It is Australia’s largest groundwater basin and extends over 1,700,000 km² or about one fifth of the Australian continent.

As with Kati Thanda – Lake Eyre, the GAB is rich in environmental and cultural values. The subsurface waters of the GAB emerge naturally through cracks in the rock and flows into springs, creeks and rivers to provide fresh water, supporting wildlife and a large number of endemic and relict species. Most springs and leakages occur on the edges of the Basin where water is close to the surface. The GAB springs and water more generally, is of deep cultural significance to Arabana people.

Water for Roxby Downs and the Olympic Dam mine site is sourced from the GAB near the southern and eastern areas of Lake Eyre. The water is pumped 200 km south to a desalination plant on the BHP mining lease, cooled, desalinated and stored for later distribution. This water extraction has raised concerns in the wider community about the impact on the GAB springs and their associated ecological, scientific, anthropological and economic significance.

The Government of South Australia’s Northern Water project aims to deliver a reliable and sustainable new commercial water source to meet the growing needs of the mining, defence, hydrogen and pastoral industries and reduce reliance on the GAB and the River Murray.

Although artesian water from the GAB could, in theory provide water to other South Australian cities and towns, the ecological and cultural impact and the requirement to cool, desalinate and pipe the water to produce drinking water of an acceptable quality would be a significant additional cost.

^[1] Hope, Pandora & Watkins, Andrew & Backway, Robert. (2010). Assessing the Climate Response to Major Surface Inundation: Lake Eyre, Australia. Environmental Science and Engineering (Subseries: Environmental Science). 10.1007/978-3-642-14779-1_24