Inland Waters Theme Report
Australia State of the Environment Report 2001 (Theme Report)
Prepared by: Jonas Ball, Sinclair Knight Merz Pty Limited, Authors
Published by CSIRO on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06750 7
Water quality and sources of pollution
This section reports on the following environmentals, which are defined in Fairweather and Napier (1998):
| Environmental Indicator | |
|---|---|
| IW 2.1 | Human criteria exceedances |
| IW 2.3 | Wastewater treatment |
| IW 3.1 | Guideline trigger levels reached |
| IW 3.2 | Algal blooms |
| IW 3.3 | a | b | c | | Nutrient loads |
| IW 3.5 | a | b | c | | Pesticide exposure |
| IW 3.6 | a | b | c | d | | Pollution point sources |
| IW 3.7 | Minesite remediation |
| IW 3.8 | Bloom contingency plans |
| IW 3.9 | Polluter pays principle |
| IW 3.11 | Waterwatch participation |
| IW 3.13 | Instream salinity trends |
Australia has limited inland surface water and groundwater resources suitable for human uses, so the protection of the quality of these waters is important. Equally important is protecting water quality to ensure that the health of Australia's inland aquatic ecosystems and endemic flora and fauna is protected. The major water quality threats to human uses of water and the health of aquatic ecosystems are: increasing instream salinity and land salinisation; siltation, nutrient enrichment and algal blooms; increasing water acidity; and pollutants such as metals and pesticides.
Salinity of surface waters
The increasing salinity of soils and inland waters is a major threat to the health of terrestrial and aquatic ecosystems and water resources in many catchments. The impacts on inland waters from increasing land and instream salinity include:
- mortality or stress of salt-sensitive plant and animal species (e.g. fish), changes in plant and animal community structures, loss of riparian vegetation, and salinisation of freshwater wetlands. These impacts are discussed in greater detail in Aquatic ecosystems. Some of the effects of salinisation can affect water quality in other ways, for example the loss of riparian vegetation can increase streambank erosion which in turn results in nutrient enrichment of inland waters.
- increased costs of water treatment and loss of water resources for human uses such as irrigation, agriculture, drinking water, recreation and industrial use. Instream salinity guidelines have been established for the different human uses of water.
The major cause of land and water salinisation in Australia is dryland salinity, and the area of land affected is predicted to triple in size over the next fifty years. Secondary salinisation can be caused by over-irrigation; however, its effects are often localised and can be more easily managed.
It should be noted that certain Australian waters have relatively high levels of salt as a result of natural influences. For example, the western zone of the Murray and many parts of south-west Western Australia are underlain by sediments of marine origin, which yield regionally saline groundwaters. Groundwater inflow into rivers, streams and wetlands in these areas provides most of the baseflow so many of these inland waters are naturally brackish or saline.