Great Artesian Basin under much of northern South Australia creates vital springs lessened by wastage of its water
Waters from the underground Great Artesian Basin discharged through mound springs, many in arid South Australia.
The Great Artesian Basin, Earth’s largest and deepest confined freshwater aquifer, seeped south to much of northeast South Australia where it discharged springs that were important in Aboriginal life and colonial settlement.
Covering more than 1,700,000 square kilometres, the basin became inland Australia’s only source of Fresh water at temperatures from 30°-100° Centigrade. The water of the Great Artesian Basin was held in a sandstone layer from continental erosion of higher ground during the Triassic (250-200 million years ago), Jurassic (200-145 million years ago) and early Cretaceous (145-66 million years ago) periods.
When much of what became inland Australia was below sea level, the sandstone was covered by marine sedimentary rock, trapping water in the sandstone aquifer. Most recharge water entered the rock formations from relatively high ground near the eastern edge of the basin (in Queensland and New South Wales) and gradually flowed south and west through permeable sandstones at a rate of one to five metres per year.
The age of the water in south-western discharge zones under South Australia was calculated at nearly two million years. Before European occupation, waters of the Great Artesian Basin discharged through mound springs, many in arid South Australia, such as Witjra-Dalhousie Springs, a group of about 60 on the western end of the Simpson Desert. These springs sustained a endemic invertebrates, such as molluscs and supported extensive Aboriginal communities and trade routes.
After Europeans arrived, the springs enabled exploration and setting up faster communications between south-eastern Australia and Europe, via the overland telegraph line between Adelaide and Darwin. The Great Artesian Basin became an important water supply for cattle stations, irrigation and domestic use, and is a vital life line for rural Australia. Bore holes were drilled to a suitable rock layer, with pressure often forcing water up without pumps.
The discovery and use of the water in the Great Artesian Basin allowed the settlement of thousands of square kilometres of country away from rivers in inland New South Wales, Queensland, and South Australia, that would otherwise have been unavailable for pastoral activities. In 1915, 1,500 bores across the basin provided 2,000 megalitres of water per day but by the 21st Century had dropped to 1,500 megalitres per day. Many bores were unregulated or abandoned, causing large water wastage over decades. In 2007 the Australian government announced more funding to bring them under control.
Many mound springs in South Australia dried up due to a drop in water pressure, probably resulting several invertebrate species going extinct. The large Olympic Dam copper and uranium mine in South Australia was allowed to extract up to 42 million litres of water daily from the Great Artesian Basin under the Roxby Downs (Indenture Ratification) Act 1982.
