Blue Mountains City Council

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Swamps and Swampcare

Blue Mountains Swamps are a biologically diverse plant community that occurs nowhere else in the world. The vegetation in these swamps range from low buttongrass clumps to large shrubs such as Hakea and Grevillea species. The swamps provide essential habitat to several Threatened Species, such as the Blue Mountains Water Skink (Eulamprus leuraensis) and the Giant Dragonfly (Petalura gigantea).

Blue Mountains swamps play a vital part in maintaining the water flows in the areas creeks and waterfalls, by storing water and slowly releasing it over time. Swamps also act as filters, purifying water prior to the release into creeks. Other threatened species such as Epacris hamiltonii and Microstrobos fitzgeraldii rely on the continued seepage from hanging swamps for survival in their specialized habitats.

There are less than 3,000 ha of Blue Mountains Swamp in existence. As they predominantly comprise many small areas, they are very susceptible to edge effects.
As the urban footprint expands to the edges of the plateau, the swamps are coming under ever increasing pressure.

The predominant threats to Blue Mountains Swamps are:

  • Sediment deposition, tunneling and channelisation from stormwater discharges
  • Nutrient enrichment
  • Weed invasion
  • Clearing for urban development
  • Mowing
  • Grazing
  • Water extraction (bores, tapping natural springs and building dams)
  • Fire (both ‘wild’ and hazard reduction)

Why are Blue Mountains Swamps often called Hanging Swamps?

One generally expect swamps to occur in low lying flat areas with poor drainage. However Blue Mountains swamps often ‘hang’ on steep valley sides where logic would suggest they shouldn't be able to occur. They are able to form because of the unique geology of the upper and mid Mountains. Rainwater penetrates the soil and then starts to seep through the permeable Narabeen sandstone layers. However when the water reaches the thin layers of impermeable claystone and ironstone interspersed among the thicker layers of Narabeen Sandstone the vertical passage of water is impeded resulting in the water being shunted sideways. Where the impermeable layers outcrop on the valley sides the groundwater trickles out continuously providing the constant moisture required to maintain swamp vegetation. Over millennia the peaty swamp soils develop from the decay of the swamp vegetation and starts extending down the slope. Have a look at a hanging swamp from a distance and often the distinctive line of the impermeable claystone layer can be seen at the top of the hanging swamp.

Swampcare

The Swampcare program has been established as part of the existing Bushcare program. Swampcare consists of:

  • Educational workshops directed at increasing the awareness and understanding of Blue Mountains Swamps and the threatened species that rely on them for their continued existence.
  • Practical workshops directed at providing community volunteers with the specialized skills needed to work in fragile swamp environments and to rehabilitate degraded swamps with soft engineering techniques.
  • On-ground work days designed to channel community energy into on-ground rehabilitation of Blue Mountains Swamp systems particularly if they are known Blue Mountains Water Skink and Giant Dragonfly sites.
  • Swampcare is the flagship program for all Blue Mountains Swamp related programs and includes Swampcare activities, Swampwatch and the Blue Mountains Water Skink and Giant Dragonfly Monitoring Program.

Fact Sheets and Posters

In February 2008, Blue Mountains City Council received World Wetlands Day funding from the Hawkesbury-Nepean Catchment Management Authority. Part of this funding was used to develop a range of fact sheets and display materials to help provide the local community with relevant information about Blue Mountains Swamps. These factsheets and posters may be downloaded, at right.