Creating a Billabong

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Billabong

Creating a Billabong

Billabongs are crescent shaped sections of a river that were once part of the main channel but have been cut off by a shift in the river’s course. Natural billabongs underpin the biodiversity and health of our river systems. They teem with life, and provide homes for an amazing number of birds and animals.

Wouldn’t it be marvellous to have a billabong in the backyard, and bring a little bit of the bush to the suburbs! Don shows how to create a spectacular piece of Australiana which will attract all the native flora and fauna to your place.

Tools Required

  •  Wheelbarrows
  • Shovels
  • Buckets
  • Levels
  • Water-based line marking paint
  • Scissors
  • Fork
  • Garbage Bin (for mulch)
  • Garden Trowel
  • Rake
  • Spade
  • Wooden Concrete Float

Creating the Billabong

  • Clear the area of weeds and rubbish.
  • Check for and locate any services that may be in the way.
  • Mark out on the ground the shape of the billabong and positions for the feature boulders using the water based marking paint, then place the liner over the marked area to ensure that it is big enough.
  • Excavate the marked area to a depth of about 450mm (18″), this allows for the sand base, liner and rock layers. The final water depth should be 300mm (12″) which is the maximum allowed by law.
  • Use excavated material to create planting mounds around the billabong. Once the basic shape has been dug out, finish excavations by hand, making sure the sides are as smooth as possible.
  • Use excavator to pick up boulders and place them into position. In the excavated hole place brickies sand to the required depth (we laid the sand to a minimum depth of 50mm or 2″). This fine sand is used to reduce the risk of puncture to the liner.
  • Smooth over with the wooden concrete float.
  • Place liner into position. Place river sand and pebbles into the base and sides of ponds.
  • Position logs in appropriate places. Logs in streams naturally trap and retain accumulated leaf litter and finer particles, so place some sand around the logs in your billabong to give the impression that it’s been washed up there by the river. Install aquatic plants. Fill billabong with water.
  • Before trimming the liner ensure that there is an overhang of at least 300mm or 12″ (see diagram), trim liner, then anchor and disguise the overhang with river pebbles.
  • Wait for the water to settle then add the fish. (Tip: Use Australian Pet Supplies Water Clarifier to speed up the settling process.)
  • Place the plastic bag containing the fish in the pond for about an hour before releasing the fish, to allow the temperatures between the bag water and the pond water to equalise. Complete planting around the billabong.
  • Mulch planted areas and water in well.

Retail Costing

Rubber Liner (E.P.D.M.) (6m x 3.5m) $18 per square metre
Sand, Brickies (1 tonne) $38 per tonne
Double Washed River Sand (0.5 tonne) $32 per tonne
Lucky Stones (1.5 tonne) $44 per tonne
Nepean River Pebbles (0.5 tonne) $44 per tonne
Granite boulders (3x) $140 each
Leaf mulch (1m3) $34 per metre square
Excavator – Hire and float (4 hrs) $360. Excavators can be hired for a half or a full day (check your local Yellow Pages). We used J. Wheeler Excavations, Cowan, NSW. Phone: (02) 9985 7777, fax: (02) 9985 7377, Mob: 0418 449 833.
Australian Rainbow Fish (Melanotaenia fluviatilis), (13x) $6.50 each
Plants (see plant lists below) $1380
Quik Mark – water-based inverted marking paint. Available in four lead-free fluorescent colours, it is manufactured by Krylon and stocked at selected Mitre10 stores for around $14 for a 340g (12oz) spray can.
Alum approx. $15 for a 2kg bag, Water clarifier $18 for a 500ml bottle
Delivery charges $30 per load

Plants

The existing garden was extended using bird-attracting native plants such as grevilleas and banksias. Banksia spinulosa has orange/yellow cylindrical flowers in autumn and winter. It will grow in all but the very hot and very cold areas of Australia

The drainage at the site was not perfect so Don positioned the plants higher than usual in the ground, making sure that at least some of the roots would be above moisture level when it rained. Because coolibah trees (Eucalyptus microtheca) don’t grow in Sydney, we planted three scribbly gums (Eucalyptus haemastoma) next to our billabong. They were placed in a clump or grove leaning out over the water, to give a Namatjira or Heysen kind of effect. These trees have beautiful smooth, white and grey mottled bark with distinctive “scribbles”. The marks often look like some mysterious form of writing, but they’re actually the tunnels of moth larvae. Scribbly gums grow in all areas except Hobart, the mountains and the tropics.

Don pointed out that plants always look good overhanging water, and also that with native plantings nothing should be symmetrical – when in doubt, make it messy. Plants were mulched with leaf mulch to a depth of 75-100mm thick (3-4″).

The aquatic plants ideally should be put in before the pond is filled, otherwise just use a few handfuls of sand to tuck them into pockets between the rocks. Some people put aquatic plants into ponds pots and all, but they do look better without the pots.

For a natural effect, Don planted rushes (Lepironia articulata) in the sort of spots where a seed would catch as it came down the river. These plants are available in metre strips and can be chopped up as required. Lepironia grows in all areas of Australia, except Hobart and the mountains.

All the plants used in our segment are listed below, along with pot sizes and the approximate retail cost. You can create your own billabong more economically by choosing slightly smaller sized pots (which are more readily available), as per the budget plant list.

Plant List (as per our segment)

Acacia fimbriata ‘Dwarf’ – 5 x 200mm (8″)
Banksia ericifolia – 2 x 300mm (12″)
Banksia spinulosa – 6 x 300mm (12″)
Brachyscome ‘City lights’ – 16 x 150mm (6″)
Eucalyptus haemastoma – 3 x 25lt

Grevillea ‘Superb’ – 3 x 250mm (10″)
Lomandra longifolia var ‘Katrinus’ – 7 x 200mm (8″)
Lomandra longifolia var ‘Cassica’ – 5 x 200mm (8″)
Poa labillardieri var ‘Eskdale’ – 14 x 200mm (8″)
Westringia ‘Zena’ – 4 x 200mm (8″)

Aquatic Plants

Lepironia articulata – 3 strips
Marsilea mutica – 3 x 160mm (6″)
Nymphoides spimula sperma – 1 x 160mm (6″)
Villarsia reniformis – 1 x 160mm (6″)

Total plant cost: $1380.00

Budget Plant List

Acacia fimbriata ‘Dwarf’ – 5 x 200mm (8″)
Banksia ericifolia – 2 x 200mm (8″)
Banksia spinulosa – 6 x 200mm (8″)
Brachyscome ‘City lights’ – 16 x 150mm (6″)
Eucalyptus haemastoma – 3 x 200mm (8″)

Grevillea ‘Superb’ – 3 x 200mm (8″)
Lomandra longifolia var ‘Katrinus ‘ – 7 x 150mm (6″)
Lomandra longifolia var ‘Cassica ‘ – 5 x 150mm (6″)
Poa labillardieri var ‘Eskdale ‘ – 14 x 150mm (6″)
Westringia ‘Zena’ – 4 x 200mm (8″)

Aquatic Plants

Lepironia articulata – 3 strips
Marsilea mutica – 3 x 160mm (6″)
Nymphoides spimula sperma – 1 x 160mm (6″)
Villarsia reniformis – 1 x 160mm (6″)

Total plant cost: $746.00

Further information

Landscaping materials (stones, river pebbles etc.) may vary depending on local availability. Ours were supplied by Australian Native Landscapes. Phone: (02) 9450 1444. Pond liners, aquatic plants and fish are available from water garden specialists and aquatic plant suppliers.