The Maribyrnong catchment lies north-west of Melbourne.
It covers an area of 1,408 square kilometres, of which:
10% retains its natural vegetation
80% is used for agriculture
10% is used for urban development – confined to greater Melbourne and larger townships within the catchment
The catchment includes the 160-kilometre Maribyrnong River – the second major river in the Port Phillip and Westernport region – which begins on the southern slopes of the Great Dividing Range, near Lancefield.
Rivers and creeks in this catchment tend to be deeply incised and have highly variable flows, with long periods of low flows. They usually have poor water quality and have lost riverbank and aquatic habitat.
The Maribyrnong catchment contains two sub-catchments:
- Upper Maribyrnong system
- Lower Maribyrnong system
Upper Maribyrnong system
The major waterways in the Upper Maribyrnong system are:
Number 3 Creek
Most of these begin in forested catchments that house significant animal and plant species, including several communities of Yarra pygmy perch and platypus. Other features special to the local community include birds of prey, grasslands and Aboriginal scar trees.
Challenges for waterway health in this system include:
the impacts of more intensive land use – such as urbanisation and agriculture
balancing the area’s social and environmental needs
Condition of key values
|Current: very low, 20-year: very low, Long-term: moderate||Platypus populations are very vulnerable, and have declined significantly since we began monitoring in 1998. We aim to stabilise populations over the next 20 years and improve them long-term.|
|Current: low, 20-year: moderate, Long-term: high||Fish populations have been fairly stable since the 1990s. There is a diverse community of fish, but only a moderate proportion of these are native. We aim to improve the numbers and abundance of native species.|
|Current: high, 20-year: high, Long-term: very high||There is a high number of frog species, though this has declined as recently as the 1990s. Our habitat works aim to improve the distribution of species.|
|Current: low, 20-year: moderate, Long-term: high||The abundance and variety of waterway-dependent bird species is low. Our vegetation works will help by expanding the area and quality of habitat.|
|Current: low,20-year: moderate, Long-term: high/td>||Most streamside vegetation is of very low to moderate quality; however some small areas (mostly in the hilly headwaters) are very high. We will continue focusing on vegetation to improve this rating.|
|Current: moderate, 20-year: moderate, Long-term: high||Macroinvertebrate conditions have remained stable since the 1990s – though this varies, with the highest being in forested waterways. We aim to maintain this, and improve it long term.|
|Current: moderate, 20-year: high, Long-term: very high||Amenity will improve in key areas as we establish natural vegetation along waterways.|
Lower Maribyrnong system
The major waterways in the Lower Maribyrnong system are:
Waterways are greatly valued by the community, who have highlighted environmental features such as remaining native vegetation, platypus and growling grass frogs. They also particularly value recreational opportunities including boating, kayaking, fishing, rowing and bike riding.
Improving waterway condition is a challenge. Water quality has been significantly reduced due to the impacts of urbanisation and development and extensive land clearing, which has left little natural streamside vegetation.
Condition of key values
|Current: very low, 20-year: very low, Long-term: low||Platypuses are in very low numbers and at high risk of extinction. Significant improvement in conditions, including flows and habitat, are needed to ensure their survival.|
|Current: low, 20-year: moderate, Long-term: high||Fish species numbers and the ratio of native to introduced species are low, though this condition has been stable since the 1990s. Works to improve fish migration and flows will improve this score.|
|Current: low, 20-year: moderate, Long-term: moderate||Frog species numbers are low but have been stable over the past decade. Their condition will improve over 20 years by linking habitat, though constraints on extensive habitat connectivity limit their long-term potential.|
|Current: low, 20-year: low, Long-term: moderate||Streamside birds are in moderate condition, with small improvements since the 1990s. Their long-term potential is limited due to constraints on extensive habitat connectivity.|
|Current: low, 20-year: moderate,Long-term: high||Native vegetation is in very low condition, though some remnant vegetation is scattered along the Maribyrnong River and Jacksons Creek, particularly in the Organ Pipes National Park and Sydenham Park.|
|Current: moderate, 20-year: moderate, Long-term: moderate||Macroinvertebrates are in moderate condition. We aim to maintain this and overcome the impacts of further urbanisation, though this limits long-term outcomes.|
|Current: low, 20-year: moderate, Long-term: high||Amenity enjoyed from waterways is low. We aim to improve vegetation along waterways, which provides a sense of naturalness and is a key influence on amenity.|