Conjunctive use - West Pilbara water supply

12 Conjunctive use -West Pilbara Scheme, Western Australia

The West Pilbara region of Western Australia has developed rapidly since the mid 1960s, through the growth of the iron ore industry and, more recently, the development of the North West Shelf Gas Project. New towns have been created at inland mining centres and coastal ports. The arid climate and the deliberately high standard of urban development have resulted in high per capita water demands, approximately double those for Perth -in the order of 500 m³/person/annum, excluding industry. Initial requirements were met in 1969 by pumping from a large and unique underground source, the Millstream aquifer, through a 105 km pipeline to the coast. This system has since been extended to other coastal towns and mining settlements. The Millstream aquifer, whilst large, is not unlimited in yield, and continuous depletion could lead to deterioration of water quality and environmental damage. Planning for future demands proceeded therefore on the basis of the conjunctive use of surface water and groundwater, with surface reservoirs being used for normal demand and the aquifer being drawn down only in periods of drought. The aquifer will be recharged from reservoir releases, as well as rain, when a drought has ended.

Public interest in the scenic and recreational values of the Millstream pool area and the special significance to Aboriginals of some rivers in the region necessitated the integration of environmental and social studies with the engineering investigations over several years -an interesting combination of technology and human values.

Australian Academy of Technological Sciences and Engineering