An ancient underground water basin the size of Libya is crucial for Australia to avoid a water crisis caused by climate change. Australia's Great Artesian Basin, covering 1.7 million sq km and lying beneath one-fifth of the country, holds 65 million gigalitres of water - about 820 times the amount of surface water in Australia. This basin, slowly replenished with 1 million megalitres of rainwater filtering through porous sandstone rock each year, could potentially meet Australia's water needs for 1,500 years if fully utilized. John Hillier, a hydrogeologist who recently completed the Great Artesian Basin Resource Study, emphasizes the vast water resources stored underground. However, he and other experts caution that the basin's water supply is at risk due to declining artesian pressure, which results in water being brought to the surface through bores and springs. If the artesian pressure drops too low, primarily because of excessive water extraction, the ancient water source will become inaccessible without expensive pumping. Some parts of the basin are as deep as two km underground, with certain areas reaching depths of 3 km from top to bottom. The basin, formed between 100 and 250 million years ago, is composed of layers of water-bearing sandstone aquifers and non-water-bearing siltstones and mudstones. Water from the basin is extracted through bores and is the sole source of water for mining, tourism, and grazing in Queensland, New South Wales, South Australia, and the Northern Territory. The Great Artesian Basin Coordinating Committee states that the underground water from the basin contributes A$3.5 billion (US$2.4 billion) annually to farming, mining, and tourism. The mining and petroleum industry utilizes 31,000 megalitres of water from the basin each year for production purposes. BHP-Billiton, a major mining company, uses 11,680 megalitres annually from the basin for its operations at the Olympic Dam mine in South Australia, with plans to increase water usage in the future. Xstrata Plc, a Swiss-based miner, is considering using water from the basin for a large coal mine in Queensland that would produce 20 million tonnes annually for 30 years. The pastoral industry is the largest consumer of water in Australia, using 500,000 megalitres annually to irrigate some of the country's most productive farmlands. Angus Emmott, who owns a cattle property in central Queensland, depends on basin water during droughts. He believes that the bores are crucial for the social and economic value of the region, which previously lacked permanent fresh water. With the increasing impact of climate change, there is a growing reliance on the Great Artesian Basin, making it important to use the water efficiently and avoid wastage. Since its inception in 1878, an estimated 87 million megalitres of water has been extracted from the basin, with up to 90 percent of it being wasted. Due to a decrease in water pressure, over 1,000 natural springs have disappeared and one-third of the original artesian bores no longer flow. The extraction of ancient basin water contributes to Australia's greenhouse gas emissions by releasing 330,000 tonnes of CO2 annually. A 15-year project called the Great Artesian Basin Sustainability project, which began in 1990, aims to protect the water supply and hydraulic pressure needed to access it. Currently, around 3,000 bores continue to pour water into 34,000 km of open bore drains, with 90 percent of the water evaporating due to the outback heat. However, more than 1,052 bores have been controlled, and many kilometers of open drains have been removed and replaced with pipelines, saving 272 gigalitres of water each year. Farmers are now using technology to control livestock access to bores and manage bore flows, leading to improved land management and pasture quality. According to Emmott, this new approach has resulted in previously dried-up bores starting to flow again. The capping and piping program has also helped prevent issues such as bogging of domestic animals, drainage maintenance costs, and soil salination. Farmers and scientists emphasize the importance of sustainable water usage to prevent a future water crisis in the Great Artesian Basin due to increased demand. Emmott emphasized the importance of taking care of communities to ensure their existence, noting that the Great Artesian Basin requires careful management as it takes a long time to recharge. A long-term sustainability report on the Basin, costing A$17 million, will focus on ensuring water availability for future mining, pastoral, and environmental development. With the increase in mining activity in the region due to the global commodities boom, authorities are anticipating a rise in extraction by the mining industry. Andy Love from Flinders University in Adelaide will lead a study on how to meet the increased demand for groundwater allocations for economic development in the area. Love stated that it is important to find a balance between development and environmental protection, but this cannot be accomplished without a better understanding of how much groundwater can be extracted safely.