Water is one of South Australia's most precious resources, for environmental, social and economic reasons. The natural occurrence of surface water and groundwater shaped Aboriginal and European settlement, providing us with fresh water for drinking, agricultural and industrial use, as well as habitats for our aquatic ecosystems. However, our use of these resources and activities near them have had some negative effects, and a State Water Plan (http://www.dwlbc.sa.gov.au/publications/ waterplan.html) has been developed to guide the management of water resources throughout the state.

Rivers, wetlands and streams support unique communities of plants and animals that are not found elsewhere. Rivers and streams are generally flowing water habitats, although they may dry out seasonally. In the arid zone rivers may only flow occasionally but can flood across vast areas. Wetlands are the swamps and marshes found along rivers and on floodplains and occasionally in arid areas, where they occur as mound springs and seasonal lakes. Wetlands can also be found along the coast as mudflats and salt marshes and generally comprise areas of standing water rather than flowing water. They can be permanently, seasonally or episodically full, with periods of complete drying.

Since European settlement, damming, diversion and the extraction of water for agricultural, domestic and industrial use has left many of our rivers, streams and wetlands deprived of water. This has affected the health of aquatic plants and animals and resulted in a decline in water quality. The return of wastewater, rising salinity and agricultural runoff has further reduced the quality of the water that remains in many regions. Habitat destruction in streams and the riparian zone (the area immediately alongside a watercourse) and the introduction of exotic plants and animals have also had severe impacts on water resources.

The most significant of these problems can be seen in the River Murray, where regulated flows have dramatically altered river ecology and water quality. There are significant opportunities to improve water use efficiency and land management practices to reduce the impacts on this river system.

South Australians mainly use water from two source types - groundwater and surface water, in particular water from the River Murray. Groundwater is water that occurs naturally below ground level. This is accessed via pumping from bores and wells. Surface water is any water that occurs on the land surface including run-off, creeks, streams, dams and reservoirs. There has been a more integrated approach to water use and management in South Australia, particularly via the Catchment Water Management Boards, over the last five years. Use of groundwater is currently above the estimated sustainable limit on the northern Adelaide Plains and parts of the South East, while use of surface water is currently above the estimated sustainable limit in the Mount Lofty Ranges. Water use in other areas is either within sustainable limits or uncertain.