Yarralumla Creek Catchment

  • Five priority projects have been chosen for the Yarralumla Creek catchment, including ponds and rain gardens.
  • An estimated $16.3 million will be invested in the catchment over three years.
  • Research indicates the combined projects will remove 49% of total suspended solids, 8% of total phosphorus and 6% of total nitrogen from Yarralumla Creek waterways.
  • The frequency and severity of erosion in Yarralumla Creek will be reduced and severe erosion in the lower reaches will be stabilised.

Proposed priority projects

Pond and potential stormwater use – Athllon Drive, Mawson

The proposed project opposite Marist College consists of a pond which may be combined with an irrigation system to use the stormwater that is captured.  It will involve landscaping such as understorey planting and provide opportunities to improve amenity to enhance the existing open space.

Rain garden, Reynolds Street, Curtin

The proposed rain garden will take advantage of an existing open space between walking paths in Reynolds Street, Curtin.  The area will be landscaped to incorporate vegetation and filtering media such as geo-sand to remove nutrients and sediment.  The project will also enhance the area and increase its appeal as a recreational space for the local community.

Rain garden -  Flood Memorial site near Service Street, Curtin

The proposed rain garden will be located in a highly visible open site in the Yarra Glen arterial corridor near Service Street in Curtin.  The area will be landscaped to incorporate vegetation and filtering media such as geo-sand to remove nutrients and sediment. The northern section of the garden will feature a boardwalk which will replace the footpath that runs east-west to a residential area.  An existing cycle path will be realigned to go around the garden.

Pond and potential stormwater use – Corner of Wilkins and Beasley Street, Mawson

The proposed pond will be established at the Mawson District Playing Fields Wilkins Street, Mawson. The project will significantly enhance the outdoor sports and recreation area and potential exists to provide irrigation water to help maintain the playing surfaces.  The pond will be landscaped to enhance amenity and habitat diversity.  The site has been chosen to minimise the removal of existing vegetation.

Creek stabilisation – Yarralumla Creek, Lady Denman Drive, Yarralumla

The proposed project will involve stabilising and revegetating the banks of Yarralumla Creek where it enters the Molonglo River just downstream of Scrivener Dam, Lady Denman Drive.  Lower banks will be landscaped with rock work to prevent ongoing erosion which is a significant problem.  The upper banks will be revegetated to improve stability and filter runoff.

Catchment facts

  • The primary waterway is Yarralumla Creek, draining from the south to the north, to the lower Molonglo River. The tributary Long Gully Creek drains the eastern part of the catchment.
  • A stormwater system was built in the 1970s to transfer water from the urban area out of the catchment as quickly as possible. This can cause dangerous fast-flowing run-off, as evidenced by a lethal flash flood that occurred in the early 1970’s.
  • The majority of the catchment is covered by long-established urban development, with an old-style stormwater network of well-connected pipes and concrete-lined channels.
Total Area – 34.35 km2

Land Use Zone

Area (km2)

Area (ha)

Area (%)

Pervious Area

14.58

1458.49

41.11%

Low Density Residential

0.04

4.37

0.12%

Medium Density Residential

10.98

1097.62

30.94%

High Density Residential

0.04

3.52

0.10%

Commercial and Industrial

2.59

258.73

7.29%

Transport

7.25

724.72

20.43%

Yarralumla Creek - Totals

35.47

3547.45

100%

Water quality issues

  • Yarralumla Creek discharges high sediment and nutrient loads into the Molonglo River.
  • Water flowing from stormwater drains is of poor quality, containing soil and sediment, organic matter (leaves and garden waste) and animal faeces.
  • The large proportion of hard surfaces in the catchment readily transports nutrients into the stormwater system, even during light falls of rain.
  • The catchment is characterised as a 'flashy system', capable of generating high loads of sediment and nutrients, and causing rapid soil erosion.
  • Water quality research indicates significant pollution comes from the upstream tributaries – Long Gully Creek and Upper Yarralumla Creek.
  • New development (urban infill) and climate change are likely to place increased pressure on the catchment.

Catchment options

The ACT Government is currently consulting on options that may be suitable for this catchment.

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