Saline land and water is a natural feature in many parts of Australia, but the changes we have brought about in land and water management caused large-scale increases in the salinisation of land and rivers across much of the continent. In the 2001 State of the Environment (SoE) report for Australia, salinisation of land and water was highlighted as an issue of growing concern—5.7 million hectares of land were identified as showing signs of salinisation, with 17 million hectares predicted to be at risk by 2050. The 2006 SoE report identified salinisation as a major pressure on biodiversity, with particular severity in the southern Murray–Darling, along the south-east coast and in catchments in south-west Western Australia. Through this period, a widespread belief developed that salinisation was among the greatest pressures on our environment, and major national programs (e.g. the National Action Plan for Salinity and Water Quality) were developed to mitigate or reverse these impacts.
In recent years, salinisation of land and water seems to have a lower profile in the national conversation about our environment. It does not appear among the priority outcomes for investment in the 2008–13 Caring for Our Country program, and is only referred to in passing as a concern. Does this mean that the threat is diminished?
With the end of national-level support for salinity management, the close, coordinated watch that was kept on the issue and thus our ability to answer that question also ended. However, in regions with previously identified salinity risks, it is widely reported that shallow, saline groundwater levels (one of the fundamental drivers of secondary salinisation) are falling. There seem to be fewer reports of spreading land salinisation.
These changes, if real, are unlikely to be due to the success of the National Action Plan for Salinity and Water Quality or other investments in salinity management, according to an analysis by Pannell & Roberts.30 This program did, however, identify where we can expect to have ongoing salinity issues. Recent changes in salinity are most likely reflecting a changing balance between saline groundwater levels and dilution flows due to the widespread drought across southern Australia. Less rainfall can mean drops in local saline groundwater levels, thus reducing the delivery of salt to soil and streams. On the other hand, reduced river flows can mean local increases in salinisation, as occurred in the Lower Murray Lakes and the Coorong during the drought.
The Murray–Darling Basin Plan is still legislatively required to have a water quality and salinity management plan. There is also a Basin Salinity Management Strategy and an Independent Audit Group for Salinity. Dryland salinity is of greatest extent in the South-west Coast division, but public concern and government or community initiatives to redress the issue have diminished over the past five years.
It will be very important to monitor how the widespread floods in the south-east of Australia in 2010 and 2011 change the salt balances in soil and rivers.