Fortunately, some portions of Australia that lack surface water supplies have substantial amounts of underground water that may be tapped by wells and bores. The Great Artesian Basin of Queensland and portions of adjoining states is well known. The basin extends southward from the Gulf of Carpentaria to the Broken Hill-Cobar uplift and thus includes the Lake Eyre and Darling River drainage.
It has a total area of 550,000 square miles, and in places the waterbearing strata are more than a mile deep. The intake for the artesian strata lies among the moist highlands to the east. Temperatures of the artesian water increase at the rate of 1° for each 20 to 50 feet of depth, depending on the locality. Salinity increases generally toward the west or in the principal direction of underground movement. Under natural conditions the artesian basin drained slowly through saline springs in the vicinity of Lake Eyre.
The most important portion of the Great Artesian Basin is in Queensland, which claims nearly two-thirds of its area. The first deep bore was completed at Blackall in 1888 to a depth of 1663 feet. By 1900 there were 524 artesian bores, with an average depth of 1475 feet, producing 224,000,000 gallons of water daily. By 1910 state laws regulated the tapping and use of artesian water. By 1914 artesian water flow in Queensland reached a maximum of 355,000,000 gallons daily from about 1200 bores. Flows have decreased slowly since 1914, and despite the fact that there were over 2000 bores in 1945 the year's flow amounted to only 225,000,000 gallons.
By 1945 about one-third of Queensland's 2000 bores had ceased to flow. The average depth of bores was between 1500 and 1600 feet, and the average yield was about 160,000 gallons for each 24-hour period. An annual average decline in flow of 1 ¾ to 2 per cent may be expected at each bore because of diminished pressure. Water may be pumped after a bore ceases to flow, but that increases costs.
The greatest concentrations of bores in Queensland occur to the east of Cloncurry and to the west of Jericho. In New South Wales most of the bores are found to the north and east of Bourke. There are a few wells near Charlotte Waters and Oodnadatta in South Australia along the route between Alice Springs and Port Augusta.
Artesian water finds its principal use in watering stock and for domestic purposes. The bores make possible the use of pastures that lack surface water but have adequate feed. There is insufficient water to meet the needs of irrigation, and its high mineral content also tends to prohibit such use. Artesian water is usually distributed by ditches for stock-watering purposes. Since the ditches are not lined, seepage losses are great, and some water is also lost by evaporation. It is estimated that less than 5 per cent of the water delivered from the well is actually consumed by livestock. It is claimed, however, that the cost of distribution by pipe lines would not be justified by the returns from the pastoral industry. The present waste of water is enormous.