Issue: Habitat scale influences - Water Quality (for surface and groundwater) - Other pollutants
This is an issue under the Inland waters theme of the Data Reporting System.
Why we need to know about this issue
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.
Although instances of toxic concentrations of chemicals, such as metals and pesticides, are not frequent, exceptions sometimes occur downstream of irrigation areas, industrial sites, disused sheep dip sites and old waste dumps.
Some principal sources of pollutants, other than excess nutrients, salt and sediments are wastewater from sewage treatment plants, pesticides and acidic discharge from mine sites or the acidification of soils in agricultural areas.
Wastewater from sewage treatment plants can contain pollutants in high enough concentrations to cause ecological harm. Sewage treatment plant discharges are also a major source of pathogens. Most sewage treatment plants disinfect their discharges to kill pathogens, but the effectiveness and reliability of disinfection varies with flow and age of the sewage treatment plant. Biological and chemical pollution of waterways can result in loss of aquatic species.
Pesticides are possibly the most widespread contaminants of inland waters. They are used extensively in agriculture, especially for the cultivation of cotton, rice, sugar cane and horticultural crops. Certain chemicals, such as atrazine and endosulfan, are regularly found in catchments where pesticides are applied to bare-soil cropping systems, as the result of runoff events that occur shortly after spraying.
Pesticides can find their way into inland waters via excess irrigation water discharged into rivers and streams, contaminated groundwater or drainage water, surface run-off from areas where pesticides have been used, over-spray and spray drift from aerial and ground spraying operations, irrigation channels where herbicides have been used to control terrestrial and aquatic weeds, volatilisation and precipitation, domestic use of pesticides on gardens and for termite control. While open water presents an immediate problem to health and aquatic organisms, groundwater contamination will persist for very long periods, and may affect future generations as well as current users.
Although acidification of inland waters is currently a localised problem, there is some evidence that this could become a significant problem in the future. As well as having direct impacts on aquatic flora and fauna, acidification of inland waters can increase the leaching of pollutants and nutrients from contaminated sediments as well as causing fundamental changes in the chemistry of rivers and streams. Naturally acid soils occupy about one-third of Australia, but many soils in agricultural areas have become more acidic.
Indicators
- IW-14 Volume of sewage discharge to surface waters by treatment category (primary, secondary, tertiary)
Wastewater from sewage treatment plants can contain pollutants in high enough concentrations to cause ecological harm.
Sewage treatment plant discharges are also a major source of pathogens. Most sewage treatment plants disinfect their discharges to kill pathogens, but the effectiveness and reliability of disinfection varies with flow and age of the sewage treatment plant.
Quantity of sewage discharge to inland waters is a direct measure of these pressures. - IW-15 Volume of sewage discharged to land
Discharge from sewage treatment plants can contribute to nutrient enrichment in rivers and streams. High nutrient levels, combined with the increased periods of low flow due to river regulation and water extraction, have caused blue-green algal blooms to become a persistent problem in some dams, wetlands and lakes.
Sewage treatment plant discharges are a major source of pathogens. Most sewage treatment plants disinfect their discharges to kill pathogens, but the effectiveness and reliability of disinfection varies with flow and age of the sewage treatment plant.
Wastewater from sewage treatment plants can contain pollutants in high enough concentrations to cause ecological harm. Discharge to land is often regarded as more environmentally beneficial because it reduces the impact on the waterways. Changes in quantity discharged to land, vis-à-vis quantities discharged to water may be indicative of an overall reduction in environmental pressure due to improvements in sewage management. - IW-16 Total pesticide use
Total pesticide use is a measure of one aspect of this pressure. - IW-21 Exceedance of pH water quality triggers
Number of exceedences of water quality triggers for pH is a direct measure of the pressure of acid soils and other pollution on inland waters. - IW-22 Exceedance of biological and chemical water quality triggers
Biological and chemical pollution of waterways can result in loss of aquatic species. Number of exceedences of water quality triggers for biological and chemical contaminants is a direct measure of the pressure of acid soils on inland waters. - CO-28 Quantity of discharges of different substances from humans activities to coastal and marine waters
A breakdown, as far as possible, of quantities of all substances discharged from coastal facilities either directly into coastal waters, or into coastal freshwater systems, gives an indication of the scale of the pressure of pollutants on freshwater systems.
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