Georges River
Water Quality and River Flow Objectives
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At a Glance |
This section gives the Water Quality Objectives (WQOs) and the River Flow Objectives (RFOs) for the Georges River catchment, which should be used to develop plans and actions affecting water quality and river health. Only the priority RFOs are listed in this section, but the remaining objectives still need to be considered when developing flow management plans or dealing with particular local river conditions.
The Woronora River supplies town water to southern Sydney and was teh subject of a Healthy Rivers Commission inquiry, which made specific recommendations. .
Mainly forested areas
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Streams in mainly forested areas are often valued for their conservation or recreational values. They often have relatively natural flows and water quality. Many are in national parks or state forests.
Map: The objectives apply to streams running through areas coloured green on the map (state forests, national parks and nature reserves), and through other forested areas, if any are defined locally.
Water Quality Objectives
Protection of:
River Flow Objectives
Supporting information
- This category covers Heathcote and Botany Bay national parks and Towra Point Nature Reserve.
- For creeks flowing mainly through forest, woodland or other natural vegetation, often the only action required to achieve WQOs is to limit faecal contamination. Little, if any, action is likely to be necessary to achieve all RFOs. High-level protection should be given to flows and water quality in these least-affected streams and in other streams with high conservation values such as O'Hares Creek.
- Some mainly forested parts of the Holsworthy Military Reserve may also be considered to be included in this category rather than the 'Uncontrolled streams' category, below.
- River flow has been affected by the construction of weirs. This factor should be taken into account to meet the RFOs for this part of the catchment.
Waterways affected by urban development
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Streams within urban areas are frequently substantially modified and generally carry poor quality stormwater. Local communities are often keen to see these waterways returned to more natural conditions.
Map: Urban development areas are shown in orange on the map.
Water Quality Objectives
Protection of:
River Flow Objectives
Supporting information
- A large part of the catchment falls within this category. Existing programs to improve water quality will be complemented by stormwater initiatives and improvements in environmental management of small industrial and commercial premises.
- In some urban waterways aquatic ecosystems are considerably modified. A return to pristine aquatic ecosystems in these areas is unlikely and impractical. However, water quality conditions for existing ecosystems can be improved greatly for the benefit of local species and broader catchment health. Data from other local aquatic ecosystems of similar type, in areas that are not urbanised, may provide achievable criteria for these modified aquatic ecosystems.
- WQOs recommended may not be achievable in the short term. Primary contact recreation may not be achievable.
- Leachate from former waste tips, excess nutrients, other pollutants from stormwater and weeds affect the Botany and Rockdale wetlands. Although extremely altered by development, they have some conservation importance as remnant wetlands in a mostly urbanised area.
- The Liverpool weir restricts fish passage on the Georges River, but a fishway has been built.
Uncontrolled streams
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Uncontrolled streams and waterbodies are waterways that are not in the other categories or the estuary. Their flow patterns are largely natural but may have been altered in some way.
Map: Uncontrolled streams are shown as blue lines on the map.
Water Quality Objectives
Protection of:
River Flow Objectives
Supporting information
- Drinking water objectives apply only to the Prospect Reservoir.
- This part of the catchment includes rural and semi-rural catchments of the Georges River, O'Hares Creek and the environs of Prospect Reservoir. This part of the catchment is rapidly urbanising and potential developments should take into account the environmental objectives.
- Forested areas in the O'Hares Creek sub-catchment and the Holsworthy Military Reserve should already meet the objectives. These areas have high conservation values and should be protected. O'Hares Creek is part of Sydney Water's declared Special Area, but has not been used for drinking water supply. (Special areas may be declared under section 44 of the Sydney Water Catchment Management Act 1998 to protect the quality of stored waters, whether intended for use for drinking or other purposes, or to maintain the ecological integrity of the land.)
- There is limited use of water from these sections of the catchment, but increasing intensity of development means loss of wetlands and their connection with the river.
Estuary
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As the estuary is dominated by saline conditions, its hydraulic and water quality characteristics, and potential problems, are often very different from those of freshwater systems.
Map: The estuary is outlined in purple on the map.
Water Quality Objectives
Protection of:
River Flow Objectives
Supporting information
- Urbanised streams affect the estuarine system of the Georges River.
- Activities within Botany Bay, such as shipping and the airport, significantly affect the quality of water in Botany Bay. Industrial activities and previous land uses, such as waste tips, have polluted the groundwater, which can also affect water quality in the Bay.
- Parts of the lower estuarine reaches are underlain by potential acid sulfate soils, which should not be disturbed. Dredging and disturbance of bottom sediments (i.e. those below water level) can also have major impacts in these areas for the same reason.
- In the medium term (5-10 years), the environmental value of aquatic foods (cooked) may be achievable. The environmental objective of 'Commercial shellfish production' has not been recommended for the Georges River as the water quality in the catchment is such that there is marginal scope for this production to continue in the future.
- In the long term (10 years or more), primary contact recreation may be achievable.
- Botany Bay has had its estuarine processes considerably modified by the building of runways at Kingsford Smith Airport, and by building and activities associated with Port Botany. These actions have caused or accelerated erosion at several locations, such as Towra Point and Lady Robinson Beach. Important fish habitat such as seagrasses has been diminished in area.
- Estuarine wetlands at Towra Point are internationally important (Ramsar-listed) and should be protected from changes to the estuarine processes.
This page was published 1 May 2006
About the Objectives
