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Indicator description Percentage exceedences of ANZECC water quality guidelines for a suite of bacterial and chemical water quality parameters for inland waters relating to:- protection of aquatic ecosystems;,
- primary contact recreation;
- irrigation; and
- stock watering.
Exceedences are reported separately for each use. Why is it indicative Water has many environmental values, including recreation, irrigation, stock watering, and the protection of aquatic ecosystems. The maintenance of these values is a critical environmental issue. Environmental water quality is usually assessed against some criterion or guideline for each separate chemical or physical variable. The 'Australian Water Quality Guidelines for Fresh and Marine Waters' (ANZECC & ARMCANZ 2000) are applied in Tasmania. Given sufficient data availability, these guidelines take into account regional variations in the environmental values of water quality, baseline environmental conditions and allow for variation in the parameters measured and frequency of measurement for each water body. Guidelines are chosen based on the primary management aims for a water body. Water quality data which trigger guideline values indicate a need for remedial management action or the initiation of further investigations confirming inappropriate levels of water pollution. Within this document the term 'percentage exceedence' of water quality guidelines has been used to gain a relative and absolute indication of water quality at a site. Percentage exceedence is defined as the percentage of samples that exceeded the guideline value over the measurement period. Selected ANZECC water quality guidelines for surface waters
 |
Parameter |
Units |
Aquatic ecosystems |
Primary recreation |
Irrigation |
Stock watering |
|
pH |
- |
6.5-7.5 |
5-9 |
6-8 |
- |
|
Conductivity |
µsiemens/cm |
90 |
- |
- |
3,730 |
|
Temperature |
o
C |
- |
15-25 |
- |
- |
|
Turbidity |
NTU |
10 |
- |
- |
- |
|
- The guidelines used depended on the availability of water quality data.
- When choosing guideline values appropriate for Tasmanian conditions:
- All sites were regarded as upland sites. Given the distribution of current sampling sites it can be generalised that even coastal sites originate from steep elevations (Greg Dowson pers comm.). As the location of sampling sites increases or changes to include more lowland sites the choice of guidelines should be reviewed to include lowland specific values.
- Considering the naturally acidic waters of Tasmania, the pH aquatic ecosystems guidelines for humic waters were chosen.
- The ANZECC aquatic ecosystems guidelines for turbidity are defined by the range 2-25 NTU for south-eastern Australia. This rather large range was customised to Tasmanian conditions using Forestry Tasmania's dataset for unlogged sites. The maximum 80th percentile of turbidity data for all 13 sites was found to be 11.46 NTU. A turbidity guideline of 10 NTU was chosen as a general approximation for defining the trigger value for the turbidity guideline.
- The guidelines chosen for stock watering were dependent upon the type of animal. Guideline values for horses, pigs and chickens were not considered because the farming intensity of these animals is low in Tasmania, requiring comparatively low water supply. The most conservative of guidelines from the remaining animals (sheep, beef and dairy cattle) was chosen i.e. dairy cattle.
Source: adapted from ANZECC (2000)
The ANZECC guidelines recommended a more conservative approach when comparing toxicant test data with default guideline values. The more stringent approach is recommended here because, unlike physical and chemical stressors, toxicant default values are based upon actual biological effects data. Hence, even a single exceedence of the guideline indicates the potential for ecological harm. Water quality guidelines for toxicants (99% protection level i.e. 99% of species expected to be protected).
|
Parameter |
Aquatic ecosystems µg/L |
Primary recreation µg/L |
Irrigation
mg/L |
Stock watering mg/L |
|
Lead |
1 |
50 |
2 |
0.1 |
|
Manganese |
1,200 |
100 |
0.2 |
- |
|
Nickel |
8 |
100 |
0.2 |
1 |
|
Zinc |
2.4 |
5,000 |
2 |
20 |
|
Aluminium |
27 |
200 |
5 |
5 |
|
Cadmium |
0.06 |
5 |
0.01 |
0.1 |
|
Cobalt |
- |
- |
0.05 |
1 |
|
Copper |
1 |
1,000 |
0.2 |
- |
|
Iron |
- |
300 |
0.2 |
- |
|
Chromium |
- |
50 |
0.1 |
1 |
|
Source: ANZECC (2000)
What does the data show - Interpretation needs to take into account the distribution of sampling sites. Sampling sites are biased towards those catchments with little human impact (i.e. non-impacted catchments or those with limited logging) or those with major impacts from mining (the Savage River and Pieman catchments). There is a significant lack of sampling sites located in catchments with agricultural or urban land uses.
- Temperature: all sites were found to be outside the recommended water temperature range for primary recreation most of the time. The small number of sites in the north-east had marginally warmer waters.
- Turbidity: the percentage of measurements exceeding aquatic ecosystem guidelines for turbidity was high at Brid, Piper, and Savage River. Medium level exceedences occurred at Tahune, Bren, Johns and Leigh. All other sites did not exceed the guideline or had low exceedences. Flow data were only available for a subset of sites in the south-eastern part of the State. At these sites, higher turbidity levels occurred during higher flows.
- Conductivity: the percentage of measurements exceeding aquatic ecosystem guidelines were high for the Brid, Cook, Piper, Leigh, Johns, Lune Lower, Savage River Station, and Huskisson River. Medium level of exceedence occurred at the Huon River. The percentage of measurements exceeding stock watering guidelines for conductivity was zero at all sites.
- pH: the percentage of measurements exceeding aquatic ecosystems guidelines were high for all smaller, upland rivers. Larger rivers had low exceedence levels for pH. The percentage of samples exceeding primary recreation pH guidelines was zero for all sites. The percentage of samples exceeding irrigation guidelines was variable. Larger streams tended to have lower exceedences. Surface waters within Lake Pieman catchment had high levels of guideline exceedences (with the exception of the Huskisson River which was lower). Moderate levels of guideline exceedences occurred at the Savage River sites.
The following summaries apply to sites only within the Pieman and Savage River mining areas: - Aluminium: aquatic ecosystem, primary recreation, stock watering and irrigation guidelines were generally exceeded at all sites.
- Cadmium: aquatic ecosystem, stock watering and irrigation guidelines were exceeded at all sites. Guidelines for primary recreation were not exceeded.
- Copper: aquatic ecosystem, stock watering and irrigation guidelines were exceeded at all sites. Lower exceedences of aquatic ecosystem guidelines occurred at Pieman compared to Savage River sites. Guidelines for primary recreation were not exceeded.
- Chromium: guidelines for primary recreation were not exceeded. There were low exceedences for stock watering. All samples at all sites exceeded chromium guidelines for irrigation.
- Manganese: a high percentage of samples exceeded guidelines for primary recreation at Savage River sites. At Pieman sites exceedences were low. All sites and all samples exceeded guidelines for irrigation. No guidelines for aquatic ecosystems were exceeded.
- Nickel: aquatic ecosystem, primary recreation, stock watering and irrigation guidelines were highly exceeded at all sites.
- Lead: guideline exceedences for aquatic ecosystems and irrigation were low at Savage River sites but high at Lake Pieman sites. No samples exceeded guidelines for primary recreations and all samples exceeded guidelines for stock watering.
- Zinc: guideline exceedences for aquatic ecosystems and irrigation were high at all sites. Low exceedences of stock watering guidelines occurred for Savage River at Pump Station and Savage River at Doody's Creek with high exceedences elsewhere. No samples at any site exceeded guidelines for primary recreation.
- Iron: guidelines for irrigation were exceeded at all sites, for all samples. Guidelines for primary recreation were low at Pieman sites and high at Savage River sites.
Data Only sites which had greater than 24 samples taken between 1996-2001 have been used. Data from the expanded network of water quality monitoring sites as shown in the first map shown below were not available in time to include with this indicator. Summary of data sources
|
Monitoring program |
Program objectives |
Manager |
|
Continuous water quality monitoring or baseline monitoring |
Develop surrogate measures to enable state of the river reporting |
DPIWE (Water Assessment Section) |
|
State of river monitoring/reporting |
Collect ambient WQ information |
DPIWE (Water Assessment Section) |
|
Bulk water supply monitoring |
Operational monitoring |
Esk Water |
|
Bulk water supply monitoring |
Operational and compliance monitoring |
Hobart Water |
|
Savage River study |
Mine site rehabilitation |
DPIWE (Environment Division) |
|
Pieman River study |
Rehabilitation and environmental assessment |
DPIWE, Hydro, councils and mining companies |
|
Huon District sampling program |
Baseline monitoring to assess forestry management techniques against code of practice conduct |
Forest Tasmania (and Forest Practices Board???) |
|
Exceedences of ANZECC guidelines for conductivity Surface water monitoring and salinity status in Tasmania's 48 planning and management catchments
Exceedences of ANZECC guidelines for pH Savage River and Pieman River
Data for toxic parameters were only available for the Savage River and Pieman River where the impacts of historic and current mining activities have resulted in intensive study and remediation. Data were available for both filtered and total concentrations of most heavy metals. Where both types of data are available and the percentage exceedences of guidelines are high, ANZECC (2000) recommends the reporting of filtered data (which have a greater bioavailability and therefore give a better indication of the toxicity of waters). Map: Location of Savage River and Pieman River Exceedences of ANZECC guidelines for aluminium (filtered) Exceedences of ANZECC guidelines for cadmium (filtered) Exceedences of ANZECC guidelines for cobalt (filtered) Exceedences of ANZECC guidelines for copper (filtered) Exceedences of ANZECC guidelines for chromium (filtered) Exceedences of ANZECC guidelines for manganese (filtered) Exceedences of ANZECC guidelines for nickel (filtered) Exceedences of ANZECC guidelines for lead (filtered) Exceedences of ANZECC guidelines for zinc (filtered) Exceedences of ANZECC guidelines for iron (filtered) Related case studies
Acknowledgment Core inland water indicator IW8 (ANZECC 2000) |
