Surface Water Quality
What the results tell us for Snowy River
Rivers in Snowy River Shire are part of the Snowy River and Murrumbidgee river catchments. The quality of surface waters for the latter catchment in the shire was good for most parameters during the current reporting period and had improved slightly since the last period. No data were available for surface waters in the Snowy River catchment within the shire.
This assessment was based on results from two monitoring site on the Murrumbidgee River for a variety of physico-chemical parameters that are key determinants of surface water quality. Apart from the median value of ammonia nitrate at one site (where it exceeded the default trigger value), the median value of all other parameters at both sites were within default trigger values.
The ammonia nitrate exceedence provides an alert to natural resource managers to take action necessary to rectify the situations giving rise to the high value recorded during the current reporting period.
The main environmental value for most water bodies in Snowy River Shire was the protection of aquatic ecosystems (see Interpreting the data). These ecosystems sustain a diverse range of plants and animals and provide a focus for water-based recreational activities and eco-tourism. Their water also sustains much of the shire's irrigated agriculture.
Trends in surface water quality
The two monitoring sites located in the council area for which data were available are below. They are both in the Murrumbidgee River catchment:
- Murrumbidgee River at Bolaro (site 41010073)
- Murrumbidgee River at Yaouk Bridge (site 41010336)
These sites were classified as upland streams.
Water quality at each site was assessed by comparing the median values of parameters for the reporting period with the appropriate default trigger values. This approach acts as a warning system to alert natural resource managers of when management changes may be needed. Although individual parameter values often exceeded the default trigger values at the time of monitoring, this did not change the median value sufficiently to trigger management action.
The median value for ammonium nitrate was above the default trigger value at the Murrumbidgee River at Bolaro site for the current reporting period, but had improved substantially since the last period (see Table 1). The median values of all other parameters at both sites were within default trigger values during the current reporting period, and many had improved slightly since the last period (see Table 1).
|Parameter* and location||Median values||Default trigger values**|
|Murrumbidgee River at Bolaro (site 41010073) view graph|
|Ammonia nitrogen (µg/L)||50||20||13|
|Dissolved oxygen (mg/L)||9||–|
|Dissolved oxygen saturation (%)||104||91||Lower limit 90 |
Upper limit 110
|Electrical conductivity (µS/cm)||32||29||350|
|pH||8||7||Lower limit 6.5|
Upper limit 7.5
|Total dissolved phosphorus (µg/L)||5||5|
|Temperature (degrees C)||17||14|
|Total oxidised nitrogen (µg/L)||6||9||15|
|Total phosphorus (µg/L)||10||16||20|
|Total suspended solids (mg/L)||1||5|
|Murrumbidgee River at Yaouk Bridge (site 41010336) view graph|
|Dissolved oxygen (mg/L)||9||10|
|Dissolved oxygen saturation (%)||101||94||Lower limit 90 |
Upper limit 110
|Electrical conductivity (µS/cm)||25||21||350|
|pH||7.6||7.2||Lower limit 6.5|
Upper limit 7.5
|Total oxidised nitrogen (µg/L)||5||8||15|
|Total phosphorus (µg/L)||8||8||20|
|Total suspended solids (mg/L)||1||1|
* µS/cm = microsiemens per centimetre; µg/L = microgram per litre; NTU = nephelometric turbidity unit; mg/L = milligram per litre; ** For information on default trigger values, see Interpreting the data.
About the data
The water quality sites covered in this report were monitored by the NSW Department of Infrastructure Planning and Natural Resources (DIPNR), which is also responsible for quality control and on-going maintenance of the data collected in its databases.
Interpreting the data
- Default environmental value
- The Water Quality and River Flow Interim Environmental Objectives (EPA 1999) for NSW, which are still current, indicate that protection of aquatic ecosystems is the default environmental value for most water bodies in the Murrumbidgee catchment (in which the shire is partly located). Although individual councils are free to assign additional or different values through local processes and based on site-specific information, so far no councils in the Australian Capital Region have done so.
- Default trigger values
- The default trigger values used in this report were those values set out in ANZECC and ARMCANZ (2000). The values applicable to the Australian Capital Region are those for 'south-east Australia for slightly disturbed ecosystems' (ANZECC and ARMCANZ 2000). The default trigger values for different water quality parameters for the protection of aquatic ecosystems are based on the type of water body in question. Compared to most other environmental objectives, the protection of aquatic ecosystems is one that requires more stringent water quality guidelines.
- Type of waterbody
- For the purposes of this State of the Environment Report, an appropriate water body type—lowland coastal rivers below 150 metres altitude or upland streams above 150 metres altitude—was assigned to each monitoring site in the shire.
The median value (i.e. middle value of a data series) for each monitoring site in the shire over the reporting period was compared with the default trigger value from the guideline values suggested in ANZECC and ARMCANZ (2000). This approach was recommended when no environmental values were set, water quality objectives were not determined, local reference sites were unavailable and local site-specific information could not be sourced. This broad reporting approach cannot be used to assess 'compliance'; it is merely a warning system to alert natural resource managers.
Other potential sources of water quality monitoring data include the Community Access to Natural Resources Information (CANRI) website and the Waterwatch program. A search of Waterwatch Australia's web-based database in July 2005 did not provide any surface water quality data relevant to Snowy River Shire.
The NSW Department of Environment and Conservation also carries out surface water quality monitoring in Kosciusko National Park. This data will be included in the next State of Environment report.
ANZECC and ARMCANZ (2000) Australian and New Zealand Guidelines for Fresh and Marine Water Quality, National Water Quality Management Strategy No. 4, Australian and New Zealand Environment and Conservation Council and the Agriculture and Resource Management Council of Australia and New Zealand, October 2000.
Environmental Protection Authority (NSW) (1999) Water Quality and River Flow Interim Environmental Objectives: Murrumbidgee River and Lake George, NSW Environment Protection Authority, Sydney, on-line at http://www.epa.nsw.gov.au/ieo/Murrumbidgee/index.htm.
EPA—see Environmental Protection Authority (NSW)