Goulburn Mulwaree
Indicator: Surface Water Quality
Results for this indicator are also available for [an error occurred while processing this directive]
What the results tell us for Goulburn Mulwaree
Goulburn Mulwaree Council covers some 3,232 km2 and includes the City of Goulburn, the villages of Marulan and Tarago, and other smaller settlements. The Council is located in both the Southern Rivers and Hawksesbury-Nepean Catchment Management Authorities. Goulburn Mulwaree has a variety of land uses including residential and industrial, with agriculture being the dominant land use which is sustained by the water from the river systems.
About half of the Council’s stormwater catchment is located upstream of Goulburn City. However of the stormwater generated in Goulburn approximately 65% of the total stormwater flow, from the south and east areas, drains to the Mulwaree Ponds. The remaining Goulburn stormwater drains from the northern areas to Wollondilly River and Kenmore Creek.
Goulburn has a formalised underground stormwater drainage network, which is fitted with 51 gross pollutant traps, to improve water quality along rivers and creeks. The management of stormwater is undertaken in accordance with Council’s Urban Stormwater Management Plan which was adopted in 2000. Other actions to improve water quality in the Management Plan include erosion and sedimentation control measures; a comprehensive education program; and the installation of sedimentation basins.(Goulburn Mulwaree WMS, 2008)
The town of Marulan has a system of channels and drains that run under roads or embankments, which discharges the stormwater runoff into Joarimin Creek. The town of Tarago uses natural drainage that flows into the Mulwaree River.
The Marulan Stormwater Management Plan also identifies activities in the town that have the potential to affect stormwater quality. These include:
- community involvement;
- behavioural and preventative strategies;
- natural ecology; and
- opportunities to filter or treat stormwater for reuse (Goulburn Mulwaree WMS, 2008).
Three key determinants of surface water quality are electrical conductivity, total phosphorus and turbidity levels. Goulburn Mulwaree Council have two monitoring sites. Data available from the Sydney Catchment Authority’s Annual Reports are also included with other physio-chemical parameters, including dissolved oxygen, pH, temperature and total suspended solids.
Trends in surface water quality
Goulburn Mulwaree's two surface water quality monitoring sites are at:
- Wollondilly River at Murray's Flat (site number E409), and
- Mulwaree River at Towers Weir (site number E457).
| Parameter* and location | Median values | Default trigger values ** | ||
|---|---|---|---|---|
| 1997– 2000 | 2000–04 | 2004-08 | ||
| Wollondilly River at Murray’s Flat (E409) | ||||
| Dissolved oxygen (mg/L) | - | - | - | |
| Dissolved oxygen saturation (%) | - | - | 74 | Between 90-110 |
| Electrical conductivity (µS/cm) | 191 | 145 | 1127 | 350 |
| pH | 8 | 6.7 | 7.6 | Between 6.5 - 7.5 |
| Temperature (degrees C) | - | - | 16 | |
| Total phosphorus (µg/L) | 80 | 9 | 21 | 20 |
| Total suspended solids (mg/L) | - | - | 2 | |
| Turbidity (NTU) | 64 | 2 | 2 | 25 |
| Mulwaree River at Towers Weir (E457) | ||||
| Dissolved oxygen (mg/L) | - | - | - | |
| Dissolved oxygen saturation (%) | - | - | 115 | Between 90-110 |
| Electrical conductivity (µS/cm) | 1001 | 587 | 693 | 350 |
| pH | 9.7 | 7.8 | 8.6 | Between 6.5 - 7.5 |
| Temperature (degrees C) | - | - | 10 | |
| Total phosphorus (µg/L) | 750 | 114 | 50 | 20 |
| Total suspended solids (mg/L) | - | - | 8 | |
| Turbidity (NTU) | 86 | 9 | 5 | 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 Murray’s Flat
The median value for electrical conductivity for electrical conductivity significantly increased over the current reporting period to more than three times the default trigger value (Table 1). The pH and total phosphorus are also slightly outside the limits for the current reporting period. The dissolved oxygen saturation is also significantly lower than the lower limit of the default trigger value.
Mulwaree River at Towers Weir
At Towers Weir the median value for electrical conductivity increased slightly over the currently reporting period. The value is almost twice the default trigger limit. However, this trend has been consistent with the previous two reporting periods between 1997 to 2000 and 2000 to 2004. The total phosphorus has significant decreased over the current reporting period, however the value is still more than twice the default trigger value. The dissolved oxygen saturation and pH median values are also both above the default trigger values, however, for the pH this has been a consistent trend over the three reporting periods.
Other studies
There is one Waterwatch site within the Goulburn Mulwaree Council.
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. 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 Water Environment and Conservation Council (ANZECC) and Agriculture 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 Council area 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
ANZECC - seeAustralian and New Zealand Water Environment and Conservation Council
ARMCANZ – see Agriculture and Resource Management Council of Australia and New Zealand
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 9 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
MDBC – see Murray Darling Basin Commission
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 - see NSW Environment Protection Authority
NSW NRA - see NSW Natural Resource Atlas
NSW Environment Protection Authority (2000) NSW 2000 State of the Environment Report – Waters Chapter
NSW Natural Resource Atlas (2008), New South Wales Natural Resource Atlas: NSW Provisional River Data, viewed at http://nratlas.nsw.gov.au on 9 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 9 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 9 October 2008
