Catchments and Water
Nature & People
Water for People and Nature
The Great Dividing Range forms the boundary between rivers flowing inland from those rivers flowing to the east coast (black line on map). These catchments capture some of Australia’s most reliable rainfall. There are many water storages in the Great Eastern Ranges corridor, supplying fresh drinking water to 93% of the population of eastern Australia. The maintenance of the health of these catchments is essential for the future health and wellbeing of our cities, towns and industries located in and adjacent to the Great Eastern Ranges.
The capacity of large dams in New South Wales is more than 25,000 gigalitres which is 50 times the capacity of Sydney Harbour. By far, the majority of these dams are located in the Great Eastern Ranges. The Snowy Mountains Hydroelectric Scheme uses snowmelt and rainfall to generate electricity and supply water for irrigating crops inland along the Murray and Murrumbidgee river systems. The electricity generated provides peak power to the national electricity grid.
How Do the Great Eastern Ranges Make Rain?
The Great Eastern Ranges act as a barrier to the moisture-laden clouds carried by winds from the Tasman Sea and Southern Ocean. They force the moisture upwards and release it as rain, snow, mist or fog that feeds the many creeks and rivers. The headwaters of many of Australia's best-known rivers such as the Murrumbidgee, Macquarie, Pages, Macleay, Nymboida, Deua, Snowy, Coxs, Richmond and Goulburn are in the Great Eastern Ranges.
As these rivers flow off the mountains and escarpments they carve their way through different geological formations creating a wide variety of highly scenic landscape features such as the intricately carved sandstone plateaus and cliffs or deep caves and sinkholes where limestone deposits formed from ancient coral reefs have been dissolved by water over millions of years.
Northern Ranges
The Northern Ranges from the Hunter Valley to the Queensland border contain several key river systems including two rivers listed as "Wild Rivers" (the Hastings and Forbes). The large areas of intact catchment are an important source of water for several municipal water supplies. Of these the Chichester Dam at 22,500 ML is the largest, and is an important water supply for Newcastle.
Sydney Basin
The Sydney Basin includes a number of protected water catchment networks and connected water supply stores providing water to over 4 million people in the greater Sydney region. Sydney Catchment Authority operates a network of 21 storages with a capacity of 2.5 million ML. Warragamba Dam provides much of Sydney with water, and at capacity can store about 2 million megalitres. The catchment area of approximately 9,000 km² receives an average of 840 mm of rain each year.
Australian Alps
The headwaters of rivers in the Australian Alps flow east and west from the crest of the Great Dividing Range in southern New South Wales, the Australian Capital Territory and Victoria. The catchment area of the strategically important Snowy Mountains Hydroelectric Scheme is about 15,500 km², of which about 8,940 km² is in NSW most of which is in Kosciuszko National Park.  The Snowy Mountains Scheme supports 16 major dams with a total storage capacity of 7,000 gigalitres. Eucumbene dam is the largest water supply store, with an active capacity of 4,366,500 ML, almost 9 times the water in Sydney Harbour. These dams provide water to Tumut and Cabramurra and also supply water to the Murray-Darling Basin, which includes 70% of all irrigated land in Australia. The Snowy Mountains Hydroelectric Scheme sends up to 3,800 megawatts of power into the national electricity grid.
South Eastern Highlands
There are 4 significant catchment water supply structures in the south-east New South Walses section of the Great Eastern Ranges. Brogo, Deep Creek, Cochrane and Yellow Pinch dams have a combined capacity of 19,600ML
Yellow Pinch Dam is an off-peak holding dam that does not collect much water from its own catchment, but depends on a gravity-fed pipeline from Tantawangalo Creek when it is in high flow. The catchment for Tantawangalo Creek is protected within the South East Forests National Park which is located along the Great Escarpment. The Tantawangalo water supply, including Yellow Pinch Dam, supplies water to Candelo, Wolumla, Tura, Merimbula, Pambula and parts of Eden, while the main water store is in the forested catchment feeding Tantawangalo Creek.
