Tumut
Indicator: Surface Water Quality
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What the results tell us for Tumut
Tumut Shire’s rivers and creeks are part of the Murrumbidgee River catchment. The water in the Shire’s rivers sustains the areas irrigated agriculture.
This assessment is based primarily on the results for three key determinants of surface water quality, electrical conductivity, total phosphorus and turbidity levels, at five sites in Tumbarumba. Other physio-chemical parameters such as dissolved oxygen, pH, temperature and total suspended solids are also reported.
Trends in surface water quality
Tumut has several water quality monitoring sites at:
- Gilmore Creek at Gilmore (site number 410059)
- Goobarragandra River crossing at Little River Road (site number 41010924)
- Murrumbidgee River at Long Plain (site number 41010152)
- Tumut River at Oddys Bridge (site number 410073)
- Tumut River at Snowy River Highway (site number 41010976)
| Parameter* and location | Median values
|
Default trigger values ** | ||
|---|---|---|---|---|
| 1997– 2000 | 2000–04 | 2004-08 | ||
| Gilmore Creek at Gilmore (410059) | ||||
| Dissolved oxygen (mg/L) | - | 10 | 9 | |
| Dissolved oxygen saturation (%) | - | 94 | 93 | Between 90-110 |
| Electrical conductivity (µS/cm) | - | 64 | 69 | 350 |
| pH | - | 7.3 | 7.2 | Between 6.5 - 7.5 |
| Temperature (degrees C) | - | - | 15 | |
| Total phosphorus (µg/L) | - | 21 | 25 | 20 |
| Total suspended solids (mg/L) | - | 7 | 10 | |
| Turbidity (NTU) | - | 6 | 7 | 25 |
| Goobarragandra River crossing at Little River Road (41010924) | ||||
| Dissolved oxygen (mg/L) | - | - | 10 | |
| Dissolved oxygen saturation (%) | 98 | 96 | 96 | Between 90-110 |
| Electrical conductivity (µS/cm) | 47 | 48 | 43 | 350 |
| pH | 7.6 | 7.5 | 7.4 | Between 6.5 - 7.5 |
| Temperature (degrees C) | - | - | 15 | |
| Total phosphorus (µg/L) | 12 | 17 | 24 | 20 |
| Total suspended solids (mg/L) | 2 | 1 | 4 | |
| Turbidity (NTU) | 3 | 4 | 4 | 25 |
| Murrumbidgee River at Long Plain (41010152) | ||||
| Dissolved oxygen (mg/L) | 9 | 9 | 9 | |
| Dissolved oxygen saturation (%) | 98 | 95 | 98 | Between 90-110 |
| Electrical conductivity (µS/cm) | 19 | 17 | 15 | 350 |
| pH | 7.1 | 7.1 | 7.1 | Between 6.5 - 7.5 |
| Temperature (degrees C) | - | - | 12 | |
| Total phosphorus (µg/L) | 11 | 12 | 16 | 20 |
| Total suspended solids (mg/L) | 2 | 1 | 5 | |
| Turbidity (NTU) | 8 | 4 | 4 | 25 |
| Tumut River at Oddys Bridge (410073) | ||||
| Dissolved oxygen (mg/L) | 9 | 10 | 9 | |
| Dissolved oxygen saturation (%) | 89 | 91 | 90 | Between 90-110 |
| Electrical conductivity (µS/cm) | 31 | 28 | 30 | 350 |
| pH | 7.2 | 6.8 | 6.5 | Between 6.5 - 7.5 |
| Temperature (degrees C) | - | - | 12 | |
| Total phosphorus (µg/L) | 116 | 23 | 17 | 20 |
| Total suspended solids (mg/L) | 1 | 1 | 2 | |
| Turbidity (NTU) | 2 | 2 | 1 | 25 |
| Tumut River at Snowy River Highway (41010976) | ||||
| Dissolved oxygen (mg/L) | - | - | 10 | |
| Dissolved oxygen saturation (%) | 94 | 97 | 90 | Between 90-110 |
| Electrical conductivity (µS/cm) | 47 | 48 | 29 | 350 |
| pH | 7.6 | 7.5 | 6.6 | Between 6.5 - 7.5 |
| Temperature (degrees C) | - | - | 13 | |
| Total phosphorus (µg/L) | 15 | 9 | 10 | 20 |
| Total suspended solids (mg/L) | - | 1 | 2 | |
| Turbidity (NTU) | 2 | 2 | 1 | 25 |
* µS/cm = microsiemens per centimetre; µg/L = microgram per litre; NTU = nephelometric turbidity unit; ** For information on default trigger values, see About the Data
Source: NSW Provisional River Data, 2008
At each site the water quality is assessed by comparing the median values of the electrical conductivity, total phosphorus and turbidity over the reporting period to the default trigger values (Table 1). Tumut Shire met the majority of these trigger values, however, the following observations are made:
- The median value of total phosphorus concentration was greater than the default trigger value for Gilmore Creek and Goobarragandra River. At both of these sites, the value was greater for the current reporting period than previous reporting periods.
- There was no significant change in the overall water quality in Tumut Shire reported for the current period.
Other studies
Two Waterwatch sites are monitored in Tumut Shire Council, at Darlows Creek (at Yaven Creek Road) and Wee Jasper.
About the data
Data for the monitoring sites covered in this report were from the NSW Department of Water and Energy (DWE) http://www.dwe.nsw.gov.au/
Data is routinely reported at http://nratlas.nsw.gov.au. DWE is 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 catchments associated with Tumut Shire. Although individual Councils are free to assign additional or different value 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 Australian and New Zealand Environment Conservation Council (ANZCC) and Agricultural and Resource Management Council of Australia and New Zealand (ARMCANZ) (2001). The values applicable to the Australian Capital Region are those for "south-east Australia for slightly disturbed ecosystems" (ANZECC and ARMCANZ 2001). 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.
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 (2001). 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.
The data was firstly sourced from the NSW Natural Resource Atlas, if the relevant data wasn’t available from this resource, the information supplied from the NSW DEW was used. The data from the NSW Natural Resource Atlas generally provided daily data on stream flow and electrical conductivity, amongst others. Whereas the data supplied by the DEW had periodic samples of the data, however did include values for the turbidity and total phosphorus.
Electrical conductivity is a measure of the ability of water to conduct an electric current. This is considered an appropriate indicator of salinity, as it is proportional to the concentration of total dissolved salts in water.
Phosphorus is considered as a key indicator of eutrophication in Australian freshwaters because it is typically a limiting nutrient for primary production under natural conditions (Cullen 1986; Donnelly et al. 1992). Total phosphorus is analysed as it represents an aggregation of all fractions of phosphorus reaching the water column from various processes and it represents the potential maximum concentration of phosphorus available for biological uptake (NSW EPA 2000).
Australia has naturally turbid waters, owing to deeply weathered soils rich in clay-sized particles. These particles are readily transported to streams during storms. Because of their colloidal nature they remain suspended in the water column, resulting in high turbidity (Cullen 1986). In addition to natural causes, the turbidity of many waters has increased as a result of human-induced erosion through practices such as land clearing (agriculture and forestry), urbanisation, extractive industries and river regulation (Walker 1985). Turbidity is a measure of light scattering and absorptive properties of water, which are roughly proportional to the type and concentration of suspended matter. It is therefore commonly used as an indicator of the amount of suspended matter in the water column, although quantitative relationships between the two are difficult to define, because various types of suspended material have different light-scattering properties.
Additional data
Other sources of water quality monitoring data include the Community Access to Natural Resources Information (CANRI) website and the Waterwatch program.
References
Australian & New Zealand Water Environment & Conservation Council (ANZECC) (1992) Australian Water Quality Guidelines for Fresh & Marine Waters, Prepared for the National Water Quality Management Strategy
ANZECC & Agricultural and Resource Management Council of Australia and New Zealand (ARMCANZ) (2001) Australian Water Quality Guidelines for Fresh & Marine Waters, Prepared for the National Water Quality Management Strategy
Australian Government (2008), Australian Natural Resources Atlas, viewed at http://www.anra.gov.au/index.html on 7 October 2008
Cullen, P. 1986, ‘Managing nutrients in aquatic ecosystems: the eutrophication problem’, in Deckker P. & Williams W.D. (eds) Limnology in Australia, CSIRO, Melbourne, pp.539–554.
Donnelly, T.H., Caitcheon, G.G. & Wasson, R.J. 1992, ‘Algal blooms in inland Australian water systems: sourcing nutrients and turbidity’, in CSIRO Division of Water Resources Divisional Report 92/4, CSIRO, Canberra, pp.74–81
Murray Darling-Basin Commission, 2008, Sustainable Rivers Audit – A report on the Ecological Health of rivers in the Murray-Darling Basin, 2004-2007, Murray Darling Basin Commission, SRA Report 1, June 2008. Viewed at http://www.mdbc.gov.au/SRA on 10 October 2008.
NSW EPA (2000) NSW 2000 State of the Environment Report – Waters Chapter
NSW NRA (2008), New South Wales Natural Resource Atlas: NSW Provisional River Data, viewed at http://nratlas.nsw.gov.au on 7 October 2008
Walker, K.F. 1985, ‘A review of the ecological effects of river regulation in Australia’, Hydrobiologia vol.125, pp.111–129
Waterwatch NSE (2006), Waterwatch NSW, view at http://www.waterwatch.nsw.gov.au/index.html on 7 October 2008
