Increasing salinity
Australia's landscape is old and is naturally more saline than other continents. Since Europeans arrived, salinity has increased within the landscape and in waterways.
There are two major causes of increasing salinity: removing native vegetation and large-scale, low efficiency irrigation systems. Both result in the water table moving closer to the surface, bringing salt with it.
High salinity can leave soil impossible to cultivate, render water unsuitable for drinking, stock watering and irrigation, and kill aquatic plants and animals living in streams and wetlands.
More information on salinity is available at the Department of Sustainability and Environment's website or alternatively at Murray Darling Basin Commission's website.