One of Australia’s greatest hidden gifts to the life that colonised it is an enormous water resource far below the ground. Spanning four states and territories over a fifth of the continent and continuing out into the Gulf of Carpentaria it is the Great Artesian Basin, and is the largest and deepest artesian water basin in the world. In some places it does resemble a basin, but it is mostly solid rock with water stored in the pores.
The GAB’s water is ancient, falling as rain or leaks from rivers west of the Great Dividing Range over a million years ago. That water takes a slow journey of one to five metres a year percolating through cracks in sandstone sheets (aquifers) held together under pressure from the impermeable stones (aquitards) above and beneath. As well as heading roughly west the water also trickles down under gravity.
Over time water is stored in vast quantities. It emerges to the ground naturally under pressure through springs and geological faults. Native plants and animals relied on springs in parched landscapes, particularly in the south-west where the Basin is shallower. Humans arrived on the continent 50,000 years ago and quickly fanned out to every corner. It is likely they swiftly found this precious resource. Burial sites 20,000 years old showed evidence of trading posts alongside artesian springs. Use of bore water dramatically increased with the arrival of Europeans into central Australia.
The first bore in 1878 found water 53m below the surface at Killara in north-west New South Wales. Within ten years, substantial finds were made at Cunnamulla and especially Barcaldine, both in Queensland. The Barcaldine bore pumped 700,000 litres a day unleashing a drilling boom and pastoral settlement in the central west. By 1900 there were more than 500 bores in the Basin thought it wasn’t easy to find water and not all were successful.
Enough reliable water was pumped out to support 120 towns and hundreds of properties in Outback Australia. Initially the pastoral industries took the most water but more recently water release by oil and gas has caught up. Mining of copper, uranium, coal, bauxite and opals also depends on water, much of it artesian, while tourist spas are also an intensive user of Basin water.
Human activity will unlikely ever dry up the Basin. In 120 years of bores about 0.1 percent of the total water was extracted from the Basin. But what it has done is lower the pressure declining the flow of water, sometimes by 80%. A third of bores have stopped flowing altogether. The springs have been severely damaged by excavation, stock and humans while exotic pests degrade the area around springs. Early bore technology was flawed too with many leaking and most were uncontrolled in their discharge of water, and 95% of the water ended up into open drains.
Diminishing flow was recognised as early as 1912 when New South Wales introduced licensing of bores and eventually vested groundwater to the state. They also brought in bore construction standards. In 1990 governments agreed on a Great Artesian Basin Sustainability Initiative (GABSI) to cap and pipe bores. Across Australia capping programs rehabilitated free-flowing bores and replaced drains with pipes but the majority of the 3000 uncontrolled bores and 34,000km of open drains remain in place.
A Strategic Management Plan was put in place in 2000 and agreed by the Council Of Australian Governments. But just like the Murray Darling (river) Basin plan, the issue of licences and multiple jurisdictions means the issue is inescapably political. The jury remains out on the impact of the extraction of large use of water for mining, especially coal seam gas mining. Graziers have to be convinced capping and piping will help them decrease their operating costs as well as increasing the pressure of the water and the reliability of its supply.
In Queensland the GAB is managed by a 10-year-plan which expires in June this year. Queensland’s government wants to cap and pipe all its uncapped bores and bore drains in the next 10-year cycle. It is, as the government policy maker I spoke to told me, “an aspirational target” but it helps show the state is serious about the problem. The new draft plan (now out for community consultation) allows for action if a licence holder fails to comply with conditions.
There are estimated to be more than 25,000 bores tapping the Queensland GAB, taking 315,000 ML a year. A diagram from the draft plan I saw at a Mount Isa community meeting showed that in 2016 around 90,400 ML was accounted for in losses through seepage and evaporation from uncontrolled bores and open bore drains. This exceeds the amount extracted by stock and domestic of 66,000 ML and the oil and gas industries 64,000 ML with other uses accounting for 93,000 ML.
Since 1989 almost 1000 bores have been rehabilitated under government-funded program but an estimated one in five uncapped bores in Queensland remain untreated while 28% of bore drains have yet to be replaced with pipelines. Under the plan all stock and domestic water users will be required to deliver water through water-tight delivery systems by the time the plan expires in 2027. Stock and domestic licences that permit free flowing bores or bore drains will require a bore management plan outlining what steps will be taken to deliver a water-tight delivery system.
The future of the Great Artesian Basin is exciting if it is managed properly. GAB water has a future as an energy source. Birdsville already has a geothermal power plant and other towns such as Winton are looking to copy it. It will make water available for future development and social and cultural activities that depend on water, including for the aspirations of Indigenous peoples in native title areas. It is crucial it is not destroyed in the same way humans are destroying Australia’s other natural wonder: the Great Barrier Reef.