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Understanding the Botany Aquifer

The Botany Aquifer is a large volume of underground water present in the sandy ground surrounding Botany Bay which runs from Centennial Park to the Botany Wetlands and into Botany Bay.

The Botany Aquifer is like a sandy sponge which holds water beneath the ground and was once Sydney's main water source.

The aquifer is recharged by rainwater percolating through sand and sandstone strata which act as natural filters to remove solid litter, silt and harmful nutrients. The water holding capacity of the sand aquifer is enormous and has been estimated to contain up to 300 litres of water per cubic metre of sand.

At its northern end under Centennial Park the water quality is very pure, however at the southern Botany Bay end of the aquifer over a century of industrial activity has caused significant chemical contamination to the water making it unsuitable for human use.

Centennial Parklands ponds form the upper catchment of the Botany Wetlands, an interconnected chain of ponds and dams which lie six kilometres downstream, where they eventually empty into Botany Bay.

These are the largest freshwater wetlands in inner-metropolitan Sydney. The ponds also play an important role in flood mitigation, acting as detention basins which slow the flow of water from the upper catchment into the lower wetlands.

The Centennial Park and Moore Park Trust (Trust) uses water from the aquifer extracted through bores for some of its irrigation needs. Bores are regulated by the NSW Department of Environment and Climate Change.

Centennial Park ponds and urban stormwater

Ten of the eleven interconnected ponds in Centennial Park, and a single pond in Moore Park, are fed by stormwater runoff from the surrounding catchment area which includes the suburbs of Paddington, Woollahra, Bondi, Queens Park, Waverley and Randwick. Only one pond, Lily Pond, is fed by a natural artesian spring.

The Trust is committed to providing good quality water which is not only important for the health of the ponds and the survival of native flora and fauna that rely on this environment but also for the health of the Botany Aquifer. The Trust uses stormwater captured in the ponds to supply a large proportion of its irrigation needs.

A number of measures have been introduced to limit pond pollution which include:

  • installing filter socks and gross pollutant traps to prevent litter entering the pond;
  • constructing concrete weirs at culvert entrances to slow water flow and better control silt entry
  • installing riparian (water’s edge) zones with native wetland plants to act as nutrient and silt filters regular sweeping of gutters and streets to minimise the amount of leaf litter and sediment being washed into the ponds; and
  • painting many of the drains in the Parklands with yellow messages to warn people that rubbish in the streets contributes to pond pollution.

You can help by:

  • sweeping your gutters and driveways with a broom rather than hosing rubbish down the drain;
  • washing your car on the grass; and
  • fertilising your lawn and garden using the minimum required rates as listed on the
    container.

Further information

For more information on the Botany Aquifer visit the NSW Department of Water and Energy website here.

Fig 1: Cross-section of the Botany Aquifer (image courtesy: University of New South Wales)

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