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Location Australia, Victoria
Central coordinates 144o 33.16' East  38o 1.58' South
IBA criteria A1, A4i
Area 3,666 ha
Altitude 0 - 10m
Year of IBA assessment 2009

BirdLife Australia

Summary The IBA supports regular numbers of the critically endangered Orange-bellied Parrot, and more than 1% of the world population of Blue-billed Duck, Australian Shelduck, Freckled Duck, Australasian Shoveler, Chestnut Teal, Musk Duck, Pink-eared Duck, Hoary-headed Grebe, Red-necked Stint and Sharp-tailed Sandpiper.

Site description The Werribee & Avalon IBA consists of wetlands from the mouth of the Werribee River to Avalon saltfields, on the shores of Port Philip Bay, south-west of Melbourne. Much of the area consists of the sewage treatment ponds of the Western Treatment Works, combined with coastal mudflats past the Point Wilson Explosives Area, to include all of the Avalon saltworks and Limeburners Bay. The sewage treatment works treats 60% of Melbourne's wastes in a series of aerobic and anaerobic lagoons and Lake Borrie, with patches of reeds and other wetland vegetation, and irrigates treated effluent onto adjacent pastures. The coast includes saltmarshes, intertidal mudflats and a small area of mangroves. The site is flat, has an annual rainfall of about 750 mm and mean maximum temperatures of 24°C in January and February to a mean minimum of 7°C in July. All of this area except for the Avalon saltworks is included within the Port Phillip Bay & Bellarine Peninsula Ramsar Site which also includes extensive areas of pastoral grasslands of little ornithological value within the Western Treatment Plant.

Key Biodiversity Significant populations of Banded Stilt (max 1846 in 2004), Curlew Sandpiper (declining, max 5074 in 2004 but previously 13,323), Red-capped Plover (max 202 in 1996), Double-banded Plover (max 519 in 1996 but subsequent counts below 310; previous max 955 and long-term mean 508), Black-fronted Dotterel (max 303 in 1983), Pied Oystercatcher (max 159 in 1985) and Red-necked Avocet (max 1166 in 2003), Black Swan (max 6879 in 2006), Hardhead (max 9784 in 2004), Pacific Black Duck (max 2231 in 2001), Great Crested Grebe (max 633 in 2005), wetland passerines, raptors, foraging site for Fairy Tern, breeding site for Pied (700 pairs; Environment Australia 2001) and Little Pied Cormorants and regular records of Australasian Bitterns, but probably not breeding (ARI database on behalf of Melbourne Water Corporation and Australian Wader Studies Group Database). Vunerable Fairy Tern recorded in 31 of 196 (16%) and near threatened Flame Robin recorded in eight of 196 (4%) Atlas of Australian Birds surveys from 1998 to 2008 (Atlas of Australian Birds database). Striated Fieldwrens are common in suitable habitat (G. Dutson pers. obs 2007); recorded in 67 of 196 (34%) Atlas of Australian Birds surveys from 1998 to 2008 (Atlas of Australian Birds database).

Non-bird biodiversity: Contains numbers of the Striped Legless Lizard and Growling Grass Frog (threatened in Australia) and Fat-tailed Dunnart (threatened in Victoria).

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Freckled Duck Stictonetta naevosa unknown  2001-2007  57-595 individuals  good  A4i  Least Concern 
Australian Shelduck Tadorna tadornoides unknown  2001-2007  3,081-18,230 individuals  good  A4i  Least Concern 
Pink-eared Duck Malacorhynchus membranaceus unknown  2001-2007  17,028-50,985 individuals  good  A4i  Least Concern 
Australian Shoveler Spatula rhynchotis unknown  2001-2007  6,608-17,433 individuals  good  A4i  Least Concern 
Chestnut Teal Anas castanea unknown  2001-2007  5,799-10,064 individuals  good  A4i  Least Concern 
Blue-billed Duck Oxyura australis unknown  2001-2007  1,784-13,000 individuals  good  A1, A4i  Near Threatened 
Musk Duck Biziura lobata unknown  2001-2007  1,436-2,103 individuals  good  A4i  Least Concern 
Hoary-headed Grebe Poliocephalus poliocephalus unknown  2001-2007  14,055-24,881 individuals  good  A4i  Least Concern 
Red-necked Stint Calidris ruficollis non-breeding  1981-2007  5,603-15,110 individuals  good  A4i  Near Threatened 
Sharp-tailed Sandpiper Calidris acuminata non-breeding  1981-2007  586-4,060 individuals  good  A4i  Least Concern 
Orange-bellied Parrot Neophema chrysogaster non-breeding  1978-2007  20 individuals  medium  A1  Critically Endangered 

IBA Monitoring

2008 medium not assessed not assessed
Good - based on reliable and complete / representative data

Climate change and severe weather storms and floods likely in long term (beyond 4 years) small area/few individuals (<10%) slow but significant deterioration low
Human intrusions and disturbance recreational activities happening now some of area/population (10-49%) no or imperceptible deterioration low
Invasive & other problematic species, genes & diseases invasive non-native/alien species/diseases - named species happening now some of area/population (10-49%) slow but significant deterioration medium
Natural system modifications other ecosystem modifications happening now some of area/population (10-49%) slow but significant deterioration medium
Pollution domestic & urban waste water - type unknown/unrecorded happening now some of area/population (10-49%) slow but significant deterioration medium
Pollution industrial & military effluents - oil spills likely in short term (within 4 years) some of area/population (10-49%) slow but significant deterioration medium

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
The Spit Nature Conservation Reserve - Wildlife Reserve (no hunting) 588 protected area overlaps with site 431  


IUCN habitat Habitat detail Extent (% of site)
Artificial - aquatic Other artificial wetlands  major
Coastline Intertidal mud, sand & salt flats; Salt marshes  major
Wetlands (inland) Freshwater lakes & pools  major

Land ownership A mix of State and private ownership - Melbourne Water is responsible for Sewage Treatment areas; Victorian Parks for reserves, intertidal areas and Bay waters; Cheetham Salt Company owns the salt works.

Land use

Land-use Extent (% of site)
nature conservation and research minor
Notes: Spit Reserve
not utilised minor
Notes: Coastal waters and mudflats
urban/industrial/transport major
Notes: Sewage treatment and salt harvesting lagoons
military minor
Notes: Point Wilson Explosives Area.

Protection status The Spit Nature Conservation Reserve.

Access/Land-Owner requests Access to the Western Treatment Plant for birdwatching is available only between 06:30-21:00 by permit ($20 for a two-year permit plus a deposit for a key). Applications can be obtained by telephoning Melbourne Water on 131722 (08:00-17:30 Monday to Friday) or over the counter at 89 Millers Road, Brooklyn, 09:00-16:00 on week days; see

Acknowledgements The nomination was prepared by Kevin Wood. The Australasian Wader Studies Group provided shorebird data. Waterfowl counts made by Bob Swindley and Arthur Rylah Institute for Environmental Research, DSE, on behalf of Melbourne Water Corporation (through Will Steele); data compiled by Phoebe Macak and Richard Loyn.

References Department of Sustainability and Environment (2003) Port Phillip Bay (Western Shoreline) and Bellarine Peninsula Ramsar Site: Strategic Management Plan, Government of Victoria.

DEWHA (2008) Directory of Important Wetlands in Australia. accessed 2008.

Hamilton, A.J. (2007) Potential microbial and chemical hazards to waterbirds at the Western Treatment Plant. Ecological Management and Restoration 8: 38-41.

Lane, B.A., Schulz, M. and Wood, K.L. (1984) Birds of Port Phillip Bay, Coastal Unit Technical Report No. 1, Ministry for Planning and Environment, Victoria.

Lane, B.A., Carr, G.W. and Orscheg, C. (1999) Conservation and Ramsar Management Plan, Western Treatment Plant, The Spit Conservation Reserve and Adjacent Habitats, Ecology Australia for Melbourne Water.

Melbourne Water (2000) Western Treatment Plant and The Spit Nature Conservation Reserve Conservation Management Action Plan. Melbourne Water: Melbourne.

Schulz, M., Beardsell, C. and Sandiford, K. (1991) Sites of Faunal Significance in the Western Wetlands of Melbourne, Wildlife Branch, Department of Conservation and Environment, Victoria.

Weston, M., McMahon, A.R.G., Fearnside, P. and Starks, J. (1995) Avalon Airshow Avifauna Study: The Effects of Aircraft Activity on Waterbirds in the Point Wilson Area. Report prepared by Ecology Australia, Royal Australasian Ornithologists Union and Carr.

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Werribee and Avalon. Downloaded from on 21/10/2016

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