Western Queensland Road Trip #12
In front of the visitor centre in Cunnamulla, crystal clear water sparkles in the sunlight as it tumbles from a pipe into a small storage pool. Drawn from an underground source far below the surface of the earth, the water first fell to earth as rainfall two million years ago.
The water comes from the Great Artesian Basin, the largest and deepest underground reservoir in the world. It covers one-fifth of subterranean Australia – 1,700,000 square kilometres beneath four Australian states and territories. In some places up to 3,000 metres deep, the basin has a capacity 130,000 times greater than Sydney Harbour. For people who live in inland Australia, this is often their only source of fresh water.
While it’s not possible to see the Great Artesian Basin, a journey through the Artesian Time Tunnel inside Cunnamulla’s visitor centre is a fascinating alternative. Going more than 100 million years back in time, the adventure begins in an old opal mine lift. The screen counts back through the centuries in a flash before the doors open to reveal an underground landscape of ancient sandstone, complete with fossils of dinosaurs and other creatures who lived in the area at that time.
Further along the tunnel sits an old opal miner, who comes alive to tell stories of life on the opal fields of western Queensland. Beyond the tunnel, displays explain how the Great Artesian Basin has enabled outback towns to flourish.
To access fresh water supply from the basin, most towns have a bore. Wells are drilled down into the earth until the aquifer is reached. Often the pressure of the water is enough to bring it to the surface, without the need for pumps. At first the water was allowed to flow freely, but now the supply is controlled. The bore at Eulo, 69 kilometres west of Cunnamulla, draws water from a depth of 223 metres. It’s hot and often smells of sulphur, but the residents are grateful to have a regular supply.
It’s not only outback towns who rely on the water. Farmers on the vast cattle properties of the west use the valuable resource for their stock. Bores like the one at Paddabilla provide welcome relief for cattle and other animals.
In some places, water from the Great Artesian Basin rises naturally to the earth’s surface. Where a weakness or fault occurs in the rock layers, the natural pressure of the trapped water forces it upwards, sometimes with tremendous energy.
In the Eulo region, a group of mud springs brings life to the desert. Even when no water flows, moisture in the soil allows plants and wildlife to flourish. A ring of flotsam around the spring shows how far the flow can extend.
In a landscape where every drop is precious, the water of the Great Artesian Basin is an asset treasured beyond measure.