Indicator: IW-17 Exceedance of turbidity water quality triggers

Data

Exceedance of water quality guidelines for turbidity, 2000
Major exceedances Significant exceedances Number of basins assessed
NSW 11 4 21
Vic 17 2 23
Qld 11 4 18
WA 2 0 3
SA 2 1 3
ACT 2 3 5
Total 41 10 67

Adapted from 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, Tables 6-11

Australia’s variable rainfall and stream flow, and highly erodible soils and streambanks combine to create naturally high turbidity levels in surface waters.

High turbidity levels are a widespread water quality issue in Australia. The affected areas include most inland and lower rainfall basins of the North-East Drainage Division, the majority of the Murray-Darling Drainage Division and the more intensively developed basins of the southern South-East Coast Drainage Division. Basins for which turbidity was not an issue include relatively well forested, less developed and higher rainfall coastal basins within the North-East Coast, South-East Coast and South-West Coast Drainage Divisions.

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, Tables 6-11

What the data mean

Turbidity is a major water quality issue in 61% of the assessed basins.

Existing widespread exceedances and predominantly increasing trends suggest that turbidity is a worsening water quality issue for Australia.

Data Limitations

NLWRA report on water resources has not been updated.

Issues for which this is an indicator and why

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

Turbidity is an indicator of the amount of soil and organic matter suspended in water. Turbidity is also an indicator of potential nutrient pollution (through the suspended material), which is an important factor in the development of algal blooms. Number of exceedences of water quality triggers for turbidity is a direct measure of this pressure.

Other indicators for this issue:

Inland Waters - Catchment scale influences - Land and vegetation condition - Erosion 

Catchment erosion and consequent sedimentation can significantly alter the physical habitat of instream environments. This produces shallowing of pools and buries coarse bottom sediments leading to a loss of habitat and spawning sites for gravel bed dependent fish. This can produce flow on effects through food chain linkages.

Turbidity is in part a measure of instream sedimentation. Number of exceedences of water quality triggers for turbidity is a measure of this pressure.

Other indicators for this issue:

Inland Waters - Catchment scale influences - Land and vegetation condition - Nutrients and sediments - sources and loads 

Erosion and surface runoff, can impact on water quality through increases in nitrogen and phosphorus loads. Number of exceedences of water quality triggers for turbidity is a direct measure of this pressure on human water supply.

Other indicators for this issue:

Human Settlements - Liveability of human settlements - Water quality 

Water quality can be diminished through increased turbidity.

Other indicators for this issue: