Lawson Creek

Lawson Creek is a significant mid-Mountains stream as it supplies moisture and nutrients to  South Lawson Park, Blue Mountains National Park and the World Heritage Area, supporting  flora and fauna diversity in these areas. It also contributes to the amenity of the popular and scenic bushwalking track between Adelina and Junction Falls. The Creek is a tributary of the Erskine Creek catchment.

Lush riparian vegetation Lawson Creek Photo: V Hong

Lush riparian vegetation Lawson Creek Photo: Vera Hong

Lawson Creek is perennial and rises south of Lawson shopping centre and the GWH, via a series of minor tributary streams and drain lines that flow into a probably quite altered swamp/lagoon complex. Originally there were many fine swamps in this area but they are now largely degraded or non-existent, although remnant peaty soils still contribute to surface seepage into the main stream. However the swamps further downstream are in a reasonable condition and as members of a protected ecological community (EPBC Act C’wlth 1999; Threatened Species Act NSW 1995) they are the subject of regular Streamwatch monitoring and ongoing bush regeneration work by a BMCC bush regeneration team.

After forming into a single, distinct channel, the Creek flows to Lawson Swamp, which is located approximately one kilometre south of the main Blue Mountains (GWH) ridge. This swamp stores and feeds a constant supply of water via Lawson Creek to two spectacular downstream waterfalls, Adelina and Junction Falls. Lawson Creek then receives significant volumes of water from Ridge and Cataract Creeks. A further two kilometres south the Creek discharges into Bedford Creek, which flows into Glen Erskine Creek to form Erskine Creek, which connects to the Hawkesbury-Nepean system.

Junctio Falls Lawson Creek. Photo: V Hong

Junction Falls, Lawson Creek. Photo: Vera Hong

Erskine Creek catchment Photo: V Hong

Erskine Creek catchment Photo: Vera Hong

Lawson Creek is in a broadly healthy condition, but the upper reaches are permanently stressed by regular adverse urban impacts such as weed growth, and these adverse impacts are often compounded in severity by specific degradation events. Such an event occurred in 2009-10, when a combination of heavy rains and massive stormwater flows, urban construction work, vegetation clearing and a collapsed track led to massive siltation of the Creek, upstream of Adelina Falls. Water flow was reduced to a trickle and macroinvertebrate life forms (bugs) disappeared for several years.

The bushcare group observed this situation and notified BMCC. A series of rehabilitative sediment control structures were installed in the Creek, to control sand flows and to create pools of water for bug habitat improvement. The Creek slowly regained its natural forms and macroinvertebrate life returned to normal levels after several years.

To some extent this massive flow of sediments was a natural event resulting from very heavy rainfall, but the concentration of stormwater flows into narrow pipes and gutters and other urban development factors such as the creation of hard surfaces and the removal of natural vegetation cover caused the flow to completely overwhelm the Creek.

2010

Stormwater overwhelmed by sand Feb 2010

Lawson Creek pipeline overwhelmed by sand Feb 2010  Photo: P.Ardill

Coir logging Feb 2010

BMCC contractors installed coir logging to enable sand dispersal Feb 2010 Photo: P.Ardill

 

 

 

 

 

 

 

Main creek channel clogged by sand Aug 2010

Lots of sand, shallow depth, poor bug habitat. Lawson Creek Aug 2010 Photo: P.Ardill

 

Remediating collapsed track Sept 2010

BMCC contractors reconstructed the collapsed section of track Sept 2010 Photo: P.Ardill

Due to its proximity to urban areas and influences, Lawson Creek requires constant monitoring for adverse aquatic impacts. Bushcare activites can provide this on-site monitoring role as well significantly helping to mitigate these adverse influences by improving vegetative ground cover quality.

For further detailed reading see Lawson Creek Condition Report 2013 at http://bmcc.nsw.gov.au/sustainableliving/environmentalinformation/livingcatchments

The Greater Sydney Local Land Services website is also a useful resource: http://greatersydney.lls.nsw.gov.au

2016

Minimal sand, sandstone bedrock, healthy Spiny Crayfish. Lawson Creek, 2016

Minimal sand, sandstone bedrock, healthy Spiny Crayfish, Lawson Creek 2016 Photo: P.Ardill

Improved condition, Lawson Creek, Nov 2016. Much less sand, more vegetative matter, better bug habitat

Improved condition, Lawson Creek, Nov 2016. Much less sand, more vegetative matter, better bug habitat Photo: P. Ardill

In 2016 BMCC bush regeneration contractors commenced swamp rehabilitation and stormwater control works at the eastern end of Ferris Lane, adjacent to the carpark. Large stands of Privet, a declared noxious weed, have been removed and a stormwater detention basin will be built, managing stormwater and weed seed flows into the upper reaches of Lawson swamp.

Unmanaged stormwater on track, flowing through weeds and carrying seed into Lawson Creek, Waratah Street, June 2007

Unmanaged stormwater  flowing through weeds and carrying seed into Lawson Creek and swamp  June 2007 Photo: P.Ardill

Stormwater and swamp works, Ferris Lane, Lawson, Oct 2016

Stormwater and swamp works, Ferris Lane Lawson Oct 2016 Photo: P.Ardill

 

 

 

 

 

 

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