Surface Water Quality
What the results tell us for Palerang
Most rivers and creeks in Palerang Council Area are part of the catchments of the Murrumbidgee and Shoalhaven rivers. The quality of surface waters in the council area was good during the current reporting period except in the upper Molonglo River.
Mongarlowe River, Tomboye
This assessment is based on three monitoring sites for a variety of physico-chemical parameters that are key determinants of surface water quality. The median values of all parameters were within default trigger values at one of the three monitoring sites. At the Googong storage inflow, one parameter marginally exceeded the default trigger value. At these sites, some parameters had improved since the last reporting period, while others had remained stable or deteriorated slightly. At the third site—Molonglo River at Burbong—the median values of two parameters did not meet the default trigger values.
The two exceedences over the current reporting period provide a warning for land managers to take action to rectify the situations giving rise to the high median values recorded in the upper Molonglo River area.
The main environmental value for most water bodies in Palerang Council Area 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. Water from the council area's rivers also sustains much of its irrigated agriculture.
Trends in surface water quality
The three monitoring sites located in the council area for which data were available are:
- Googong storage river inflow (site 41010199) (Murrumbidgee catchment)
- Molonglo River at Burbong (410705) (Murrumbidgee catchment)
- Shoalhaven River at Warri (215002) (Shoalhaven catchment)
All three 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 (see Table 1), this did not change the median value sufficiently to trigger management action.
Apart from median pH which was marginally over the default trigger value at the Googong Storage, the median value of all other water quality parameters at the Googong storage river inflow site and the Shoalhaven River at Warri site were within the default trigger values during the current reporting period (see Table 1). Some parameters had improved since the last reporting period, while others had remained stable or deteriorated slightly.
At the Molonglo River at Burbong site, the median value for dissolved oxygen saturation was below the lower limit for the default trigger value during the current reporting period, while the median value for electrical conductivity was above the default trigger value. Other water quality parameters at this site were well within the default trigger values for the current period (see Table 1). No comparative data were available for the previous reporting period at this site.
|Parameter* and location||Median values||Default trigger values**|
|Googong storage river inflow (site 41010199) view graph|
|Dissolved oxygen (mg/L)||9||10|
|Dissolved oxygen (% saturation)||98||96||Lower limit 90 |
Upper limit 110
|Electrical conductivity (µS/cm)||88||74||350|
|pH||8.1||7.7||Lower limit 6.5|
Upper limit 7.5
|Total oxidised nitrogen (µg/L)||5||10||15|
|Total phosphorus (µg/L)||9||14||20|
|Total suspended solids (mg/L)||2||2|
|Molonglo River at Burbong (410705) view graph|
|Dissolved oxygen (% saturation)||–||79||Lower limit 90 |
Upper limit 110
|Electrical conductivity (µS/cm)||–||372||350|
|pH||–||7.4||Lower limit 6.5|
Upper limit 7.5
|Total phosphorus (µg/L)||–||11||20|
|Total suspended solids (mg/L)||–||2|
|Shoalhaven River at Warri (215002) view graph|
|Electrical conductivity (µS/cm)||104||116||350|
|Total phosphorus (µg/L)||15||13||20|
* 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; – = no 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 catchments associated with the Australian Capital Region. 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 council area.
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 (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 for Palerang Council Area.
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, NSW Environment Protection Authority, Sydney, on line at http://www.epa.nsw.gov.au/ieo.
EPA—see Environmental Protection Authority (NSW)