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TRANSBOUNDARY WATER MANAGEMENTFirst steps towards wider cooperationDeveloping environmental consciousness has beenspurred by periodic droughts. For example, in the 1980sone such severe drought over the eastern half of thecontinent (initiating dust storms, water restrictions andhorrific fires) resulted in economic loss of around $A3billion. Accompanied by mounting evidence of decline,this episode instigated many inquiries, reports and calls foraction. Essentially, a shared understanding developed thatconsumption levels were more than the river system couldstand year-by-year; and there was a sufficiently compellingcase for wider cooperation for the greater good.As a more holistic view developed of the interconnectednessof all the water resources and the peopledependent upon them, the signatories to the thenMurray–Darling Basin Agreement began workingtowards more effective, coordinated and equitable plandrought)can result in limited flow to the floodplains of the lowerreaches and out of the Murray mouth in South Australia.Sufficient flow is vital as, in an average year, 2 million tonnes ofsalt leaches out of old soils and rocks and flows down the Murray–Darling. Without flushing flows salinity levels quickly build up,causing ecosystem damage, threatening agricultural production andreducing drinking water quality. Since the European development ofthe basin, flow has reduced by 75 per cent on average. The Murraymouth silts up and, during drought, remains open only by constantdredging of a narrow channel.In Australia’s federal system (whereby independent coloniesbecame states, which then joined to become the Commonwealthin 1901), water management has until very recently remained apower of the individual state/territory governments. While thesegovernments have cooperated to jointly manage the basin’s waterresource (through two key agreements: the River Murray WatersAgreement of 1914 and the Murray–Darling Basin Agreement of1987 and 1992), the primary focus has been on the fair distributionof water for consumption. States and the Commonwealth alsoworked together to construct dams, locks and weirs to secure watersupplies, prevent undesirable flooding and improve navigability.However, this river regulation and a quadrupling of surfacewater consumption between the 1930s and 1990s unintentionallyresulted in escalating environmental problems. Water storage andconsumption has disrupted the pattern of flow and prevents mostnaturally occurring small-to-medium-sized flood events. In thelower reaches of the system, many wetlands experience‘man-made droughts’ in over 60 per cent of years(compared to 5 per cent natural droughts pre-development).Consequently, there is a reduced area of healthywetland, frequent algal blooms and (without flow triggersfor spawning) declining native fish numbers. Theremoval of tree cover combined with irrigation led torising water tables, mobilizing yet more salt.Case study: environmental benefit from cooperative effortImage: Arthur Mostead, 2008The above image shows the Coorong during the millennium drought. The bright orange patches indicate the presence of iron sulphide. Ifleft undisturbed and covered with water, sulphidic sediments pose little threat. However, when exposed to oxygen, such as under droughtconditions, chemical reactions may lead to the generation of sulphuric acid. When this is wet again and released back into the rivers, itcauses substantial environmental damage and serious impacts on water supplies and human health[ 78 ]