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Centennial Parklands' ponds form the upper catchment of the Botany Wetlands, which lie six kilometres downstream. Botany Wetlands is the largest freshwater wetland system in inner-metropolitan Sydney – 59 hectares spread over a four kilometre corridor).

The Centennial Park ponds, covering an area of approximately 26 hectares, provide important habitat for water birds and aquatic life and are a significant feature of the formal design of Centennial Park.

The ponds also play an important role in flood mitigation, acting as a detention basin. Ten of the eleven interconnected ponds in Centennial Park, and single pond in Moore Park, are fed by stormwater runoff from the surrounding catchment area. This includes the suburbs of Paddington, Woollahra, Bondi, Waverley and Randwick. Only one pond, Lily Pond, is fed by a natural artesian spring.

How the ponds were formed

Prior to its establishment in 1888, the area now known as Centennial Park was known as the Lachlan Swamp. Water from this natural freshwater drainage area was channelled via Busby’s Bore to the settlement of Sydney. This water was Sydney’s main source of drinking water between 1837 and 1859, until mismanagement and poor maintenance of the bore compromised the water supply. Industry and the use of the Lachlan Swamp for livestock grazing gradually polluted the water supply.

Seven new dams, constructed to replace existing ones that were destroyed by large scale flooding in 1874, further worsened pollution. When Centennial Park was established these most recently constructed dams were remodelled into the ornamental ponds seen today. They are an integral part of the park’s Victorian design. Each pond has unique features and provides habitat for an array of aquatic wildlife.

Pond management

Management of Centennial Park ponds includes the following activities:

  • Water quality monitoring;
  • Control of environmental weeds;
  • Cleaning and disposing of waste from Gross Pollutant Traps and litter removal from pond edges;
  • Maintenance of water level control weirs;
  • Removing accumulated sediment;
  • Bank erosion control and maintaining structural integrity of walls;
  • Establishment of reed beds and planting native plants along pond edges and islands;
  • Control the presence of carp in ponds.

Gross Pollutant Traps (GPTs) are installed at stormwater entry points to reduce the amount of pollutants entering the system. Although the GPTs remove gross solids very well, they do not remove the dissolved nutrients and suspended particles present in the water column.Such pollutants can cause blue green algae blooms.

Macrophytes (aquatic plants) have been planted to provide improved habitat and to filter dissolved pollutants such as phosphorus in the water. Plantings and improvement works around the ponds’ edges have been carried out to assist with bank stabilisation. There are ongoing efforts to reduce numbers of European carp (an invasive species), and a native fish called Australian bass has been introduced.

Islands and underwater berms have been constructed to ensure that water movement around the pond is maximised to prevent areas from becoming stagnant. Adjustable weirs allow better control of water levels within and between the ponds in the system.

It is against Parklands Regulations to ‘bathe, wade, wash or swim, or operate a boat, canoe, kayak or any other water craft or vessel or flotation device, in any lake, pond or stream or in any ornamental water’. Dogs should not go in the water and must be on a leash within 10m of the ponds.

Preventing pond pollution

A number of measures have been introduced to prevent pond pollution. Gutters and streets are swept regularly to minimise the amount of leaf litter and sediment being washed into the ponds.

Everybody living in the Centennial Parklands catchments can assist in reducing pond pollution, and can make sure that our waterways are kept clean and healthy by doing the following:

  • Always sweep your gutters and driveways with a broom rather than hosing rubbish down the drain.
  • Always wash your car on the grass. Putting soapy water down the drain encourages the growth of algae and can sometimes poison our aquatic wildlife. Always pick up your dog’s poo.