Indicator: IW-19 Exceedance of total nitrogen and phosphorus water quality triggers

Data

Exceedance of water quality guidelines for Total Nitrogen
Major exceedances Significant exceedances Number of basins assessed
NSW 1 2 3
Vic 17 6 25
Qld 5 4 11
WA 2 3 7
SA 2 3 5
ACT 5 0 5
Total 19 19 50

Adapted from source: National Land and Water Resources Audit 2001, Australian Water Resources Assessment 2000. Surface water and groundwater - availability and quality, Land and Water, Canberra, viewed 5 Dec 2005, http://audit.ea.gov.au/ANRA/water/docs/national/Water_Quality.html.

Exceedance of water quality guidelines for Total Phosphorus
Major exceedances Significant exceedances Number of basins assessed
NSW 16 7 27
Vic 18 4 25
Qld 4 5 15
WA 1 4 7
SA 3 1 4
ACT 0 0 0
Total 42 20 75

Adapted from source: National Land and Water Resources Audit 2001, Australian Water Resources Assessment 2000. Surface water and groundwater - availability and quality, Land and Water, Canberra, viewed 5 Dec 2005, http://audit.ea.gov.au/ANRA/water/docs/national/Water_Quality.html.

Widespread exceedances of water nutrient guidelines occur across Australia. They affect the majority of the more intensively developed basins in the North-East Coast, Murray-Darling, South-East Coast and South-West Coast Drainage Divisions. Basins with nutrient levels within guidelines are generally the relatively well-vegetated and less developed ones within areas such as north Queensland, north-eastern Victoria and south-western Western Australia.

The available trend data suggests that:

  • six of the basins with exceedances in the Murray-Darling Drainage Division had decreasing nutrient concentration trends, while two basins had increasing nutrient concentration trends;
  • six affected basins within the southern Victorian section of the South-East Coast Drainage Division showed increasing nutrient concentration trends, and three basins showed decreasing nutrient concentration trends; and
  • one basin in the North-East Coast Drainage Division (Tweed) also showed a clear increasing nutrient concentration trend.

Source: National Land and Water Resources Audit 2001, Australian Water Resources Assessment 2000, Land and Water Australia, Canberra, viewed 13 Apr 2005, http://audit.ea.gov.au/ANRA/water/docs/national/Water_Use.html.

What the data mean

Nutrients are a major water quality issue in about 60% of the assessed basins.

Data Limitations

NLWRA data have not been updated since its report was published in 2001.

Issues for which this is an indicator and why

Inland Waters - Habitat scale influences - Water Quality (for surface and groundwater) - Nutrients 

Nitrogen and phosphorus levels can limit the availability of water resources and the indicator provides information that will help managers meet current and future needs. Eutrophication and toxic algal blooms can make surface water unsuitable for drinking or recreational purposes and can impact on ecosystems. The measure of total nitrogen and total phosphorus gives an estimate of eutrophication potential and high concentrations in surface waters are linked to algal blooms. Number of exceedences of water quality triggers for total nitrogen and total phosphorus is a direct measure of this pressure.

Other indicators for this issue:

Inland Waters - Habitat scale influences - Water Quality (for surface and groundwater) - Sediment and turbidity 

Changes in nitrogen and phosphorus concentrations, through erosion and surface runoff, can impact on water quality. Sediments can transport nutrients. Number of exceedences of water quality triggers for suspended solids is an indirect measure of this pressure.

Other indicators for this issue:

Biodiversity - Pressures on biodiversity - Pressures on marine biodiversity: pressures of coastal activities 

In addition to placing pressure on freshwater biodiversity, nitrogen and phosphorus loads reaching the coasts, place pressure on coastal and marine biodiversity.

Other indicators for this issue:

Coasts and Oceans - Direct pressure of human activities on coasts and oceans - Direct pressure of coastal activities (other than shipping and fishing) 

Agricultural land use disturbs soils and can change loads of nitrogen and phosphorus entering inland waters and ending up in coastal waters where in can place pressure aquatic and estuarine species as well as on other coastal species that rely on the water source. Quantities of nitrogen and phosphorus concentrating in surface water catchments are a direct measure of this pressure.

Other indicators for this issue:

Human Settlements - Liveability of human settlements - Water quality 

Water quality can be diminished through increased nitrogen and phosphorus loads. Number of exceedences of water quality triggers for nitrogen and phosphorus is a direct measure of this pressure on both human and environmental water supply.

Other indicators for this issue:

Further Information