Blue Mountains swamps

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, tunnelling 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 expects 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 Narrabeen sandstone layers. However when the water reaches the thin layers of impermeable claystone and ironstone interspersed among the thicker layers of Narrabeen 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 start 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.

Swamp remediation

‘Save our Swamps’ (S.O.S) program
Blue Mountains City Council's Upland Swamp Rehabilitation Program was commenced in 2006 after Blue Mountains Swamps were listed as part of the Temperate Highland Peat Swamps on Sandstone endangered ecological community, with the aim of protecting and restoring Blue Mountains Swamp across the local government area (LGA).

In August 2008 Blue Mountains City Council and Lithgow City Councils formed a partnership to deliver the ‘Save our Swamps’ (S.O.S) project to restore Temperate Highland Peat Swamps on Sandstone across both LGAs supported by grant funding of $250,000 over 3 years from the Urban Sustainability program of the NSW Environmental Trust.

The ‘Save our Swamps”’ project has been assisting in the management and conservation of the nationally threatened Temperate Highland Peat Swamps on Sandstone ecological community across the Blue Mountain and Lithgow LGAs. The SOS project has delivered a three part program that includes

  • education and community awareness raising
  • community and agency capacity building and;
  • an on-ground program of Temperate Highland Peat Swamps on Sandstone EEC (THPSS) swamp rehabilitation across both LGAs.

In 2009 the ‘Save our Swamps’ project received a $400,000 federal ‘Caring for Country’ grant to expand the program to incorporate Wingecarribee Shire Council and Gosford City Council. The partnership of the four councils resulted in the ‘Save our Swamps’ model being rolled out over 95% of the extent of the THPSS EEC.
 
The innovative integrated and landscape scale approach to the management of THPSS has resulted in the ‘Save our Swamps ‘project receiving four awards including:

  1. National Governments Local Government Award for Innovation in Natural Resource Management 2010
  2. United Nations World Environment Day Award for Excellence in Overall Environmental Management 2011 (Special Commendation)
  3. NSW Sustainable Cities award for Biodiversity Conservation 2010
  4. National Keep Australia Beautiful (Tidy Town award) for Biodiversity Conservation 2011

Soft engineering for swamp remediation

As part of a collaborative approach to information and skill sharing the practical knowledge and lessons learnt from the Save Our Swamps project, BMCC has developed a practical set of guidelines entitled
 
Download the 'Soft engineering solutions for swamp remediation: 'how-to' guide' below
 
The guide was created by Blue Mountains City Council with the assistance of Lithgow City Council, Gosford City Council, Wingecaribee Shire Council.
 
This publication comprehensively covers soft engineering swamp rehabilitation applications, techniques and materials. It also covers background information on swamp geomorphology, threats and impacts to Temperate Highland Peat Swamps on Sandstone swamps.

Current restoration works

Current works under the program include soft engineering and/or weed control at the following sites on Public Lands:

  • Marmion Swamp- major instream works, weeding and planting
  • Yosemite Creek - bank stabilisation and water spreading below stormwater outlets
  • Connought Swamp, Blackheath - instream works to stabilise headcutting after post-fire erosion of channel
  • San Jose Swamp, North Lawson - track closure and remediation of damage caused by illegal 4WD use
  • Wilsons Glen - track closure and weeding
  • Pine Avenue, Wentworth Falls - treatment of stormwater outlet, water spreading, track closures, and remediation of incised channels
  • Bass Road, Wentworth Falls- sediment control below stormwater device. Major remediation of deeply incised channels and piping.
  • Jamison Creek - comprehensive treatment of weeds