Grawin Goodooga Rd
50Km west of Lightning Ridge<

The Great Artesian Basin is 670,000 sq mi (1,735,300 sq km) in area and makes up one fifth of the area of Australia. It extends from the Gulf of Carpentaria at the top end of Queensland right through to the north east of South Australia and the north west of New South Wales. It is the world's largest artesian water-bearing area. The basin receives its water supply from the Eastern Highlands as rain is absorbed through the porous layers of sandstone rock and then flows underground. It contains some 64 900 million Megalitres of water with millions of bores. These bores supply an endless amount of water without aid of a pump in most cases. The Great Artesian Basin was once part of a hugh inland sea. It is not uncomon to find opalised fossils of many types of prehistoric sea creatures when mining for opal. All of Australia's precious opal is found wthin the confines of this basin. This of course, includes Lightning Ridge.