The Western region includes the Avoca, Wimmera-Avon (including the Avon-Richardson River), Millicent Coast, Glenelg, Portland Coast, Hopkins, Lake Corangamite and Otway Coast river basins and the southern half of the Mallee river basin. Major towns include Horsham, Stawell, Ararat, Hamilton, Warrnambool and Portland.
Bulk water provider Southern Rural Water, along with five regional urban water corporations (Wannon Water, Grampians Wimmera Mallee Water (GWM Water), Barwon Water, Central Highlands Water and Coliban Water) supply water to the Western region's cities and towns. The CMAs responsible for this region are Corangamite, Glenelg Hopkins, Wimmera, Mallee and North Central.
Water resources vary throughout this region, with the south having a relatively reliable rainfall. The south and west of the region have good groundwater reserves, and conditions are drier to the north. On average there is 2,946 GL a year of surface water available in the region and about 246 GL of groundwater available for extraction. The majority (80 per cent) of the surface water is reserved for environmental use, while irrigation water use relies on groundwater sources.350 The supply systems transfer some of the water from areas with more reliable water resources to support towns, farms and industry in drier parts of the region. Notably, the Wimmera-Mallee pipeline system is one of the largest piped stock and domestic systems in Australia.
Climate variability and drought create uncertainty about future water supplies, particularly away from the wetter coastal areas. Water management needs to consider the risks associated with possible repeats of past drought years. Other pressures include increased demand from towns, agriculture and industry, and activities that intercept water before it reaches rivers and aquifers.
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350. Victorian Department of Sustainability and Environment (2011a)