Upper Lachlan
Indicator: Surface Water Quality
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What the results tell us for Upper Lachlan
The majority of the Upper Lachlan Shire’s rivers form part of the Lachlan River catchment, however, some of the Shire area also drains into the Hawkesbury River catchment. Water from these river systems also sustains much of Upper Lachlan Shire’s 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 one water quality monitoring site in Upper Lachlan Shire. Other physio-chemical parameters are also reported, including dissolved oxygen, pH, temperature and total suspended solids.
The water quality monitoring site is in the Hawkesbury River catchment, on Wollondilly River at Golden Valley. Other water quality sites are sampled in the Lachlan River catchment, such as Lachlan River at Numby and Abercrombie River at the Camping Ground, however no data was reported for these sites during the current reporting period.
Trends in surface water quality
Surface water quality in the Upper Lachlan Shire monitored at Wollondilly River at Golden Valley (site E450).
| Parameter* and location | Median values | Default trigger values ** | |||
|---|---|---|---|---|---|
| 1997–2000 | 2000–04 | 2004-08 | |||
| Wollondilly River at Golden Valley (E450) | |||||
| Dissolved oxygen (mg/L) | - | - | - | ||
| Dissolved oxygen saturation (%) | - | - | 83 | Between 90-110 | |
| Electrical conductivity (µS/cm) | 908 | 450 | 326 | 350 | |
| pH | 9.2 | 8.2 | 7 | Between 6.5 - 7.5 | |
| Temperature (degrees C) | - | - | 15 | ||
| Total phosphorus (µg/L) | 890 | 11 | 10 | 20 | |
| Total suspended solids (mg/L) | - | - | 2 | ||
| Turbidity (NTU) | 627 | 2 | 2 | 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: Sydney Catchment Authority, 2007
Wollondilly River at Golden Valley
The median value for electrical conductivity at Golden Valley reduced over the current reporting period, to an acceptable limit lower than the default trigger value (Table 1). The electrical conductivity trend has been consistent with the previous two reporting periods, falling significantly each time. The pH and total phosphorus for the current reporting period were also within the default trigger values. A similar trend for these two physio-chemical parameters exists for the previous two reporting periods.
The dissolved oxygen saturation was below the lower limit of the default trigger value for the current reporting period. No trend for this parameter is able to be established, as it has not previously been reported.
Overall the water quality has improved marginally in Upper Lachlan Shire for the current reporting period.
Other studies
No information was available on the Waterwatch monitoring programs for Upper Lachlan Shire.
About the data
Data for these sites were supplied and monitored by the Sydney Catchment Authority.
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 Boorowa 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 Enviroment Conservation Council and Agricultural and Resouce Manangement Council 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 Department of Water and Energy (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 potential sources of water quality monitoring data include the Community Access to Natural Resources Information (CANRI) website and the Waterwatch program.
References
Australian and New Zealand Water Environment and Conservation Council (ANZECC) (1992) Australian Water Quality Guidelines for Fresh and Marine Waters, Prepared for the National Water Quality Management Strategy
ANZECC and Agricultural and Resource Management Council of Australia and New Zealand (ARMCANZ) (2001) Australian Water Quality Guidelines for Fresh and 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 10 October 2008
Cullen, P.1986, Managing nutrients in aquatic ecosystems: the eutrophication problem, in Deckker P. and Williams W.D. (eds) Limnology in Australia, CSIRO, Melbourne, pp.539–554.
Donnelly, T.H., Caitcheon, G.G. and 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 Commiaaion, 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 Environment Protection Authority (2000) NSW 2000 State of the Environment Report – Waters Chapter
NSW Natural Resource Authority (2008), New South Wales Natural Resource Atlas: NSW Provisional River Data, viewed at http://nratlas.nsw.gov.au on 10 October 2008
Sydney Catchment Authority (2008), Annual Water Quality Monitoring Reports, New South Wales Government, Sydney Catchment Authority, viewed at http://www.sca.nsw.gov.au/water-quality/water-quality-monitoring-reports on 10 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 10 October 2008
