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The Maribyrnong catchment is located to the north-west of Melbourne. Water flows from the headwaters around Mount Macedon to form Jacksons Creek, which flows into Rosslynne Reservoir near Gisborne. Water is released from Rosslynne Reservoir back into Jacksons Creek, and where it joins with Deep Creek (flowing from the north) the Maribyrnong River is formed at Keilor North. The river runs south through Yarraville in inner Melbourne before meeting the Yarra River and flowing into Port Phillip Bay.

The Maribyrnong system continues to be an important place for Traditional Owners and their Nations. The Registered Aboriginal Party (RAP) in the Maribyrnong River area is the Wurundjeri Land and Compensation Cultural Heritage Council Aboriginal Corporation. RAP representatives were involved in preparing the Maribyrnong system seasonal watering proposal.

System map

Maribyrnong system

Environmental watering objectives in the Maribyrnong River

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Maintain or rehabilitate in-stream vegetation and reduce invasive terrestrial plants from encroaching into the riparian zone
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Maintain and increase feeding and breeding habitat for native fish Protect and increase populations of native, small-bodied fish by providing flows for them to move upstream and downstream
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Support a wide range and high biomass of waterbugs to break down dead organic matter and support the river’s food chain
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Maintain water quality, particularly dissolved oxygen concentrations, by flushing pools

Environmental values

The upper Maribyrnong catchment contains areas of intact streamside vegetation, which provide important habitat for native fish including migratory short-finned eels, common and ornate galaxias, flathead gudgeon, tupong and Australian smelt. A large population of waterbugs provides an abundant food source for a significant platypus population in several reaches in the Maribyrnong system.

Social and economic values

The Maribyrnong River, fed by Jackson's Creek and Deep Creek, is located in the western suburbs of Melbourne and supplies water (primarily from Rosslynne Reservoir on Jacksons Creek) to urban and rural users.

From Gisborne to Yarraville, the river corridor's parklands, creeks and rivers provide opportunities for boating, fishing, cycling, walking and picnicking. The river at Keilor is used for canoeing and has three ponding points, which have been designed to enable children and adults to catch fish with a hand net. There are nine boat landings along the river (most notably at Canning Reserve, Maribyrnong Park and Fairbairn Park) and the river hosts water-based events including the University of Melbourne intercollegiate regatta, Canoeing Victoria's Winter Marathon Series and Scouts Australia paddling events.

Conditions 2018

Rainfall and run-off into storages and waterways of the Maribyrnong system have remained below average since summer 2016–17. Dry conditions through winter/spring 2017 meant that winter/spring low-flow requirements in reaches 6 and 7 were either not met or only partially met.

Conditions remained dry over summer and into autumn 2018. Water for the environment was used to deliver freshes to reaches 6 and 7 in autumn 2018, to prevent adverse water-quality conditions. Maintaining adequate dissolved oxygen concentrations is essential for fish and waterbugs and for platypus, which feed on waterbugs. The autumn freshes also provided opportunities for fish to move throughout the reaches and helped support aquatic plants.

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for the Maribyrnong River

Potential environmental watering1

Environmental objectives

Summer/autumn freshes (up to 5 events of 20–40 ML/day for up to 7 days) in December–May

  • Maintain water quality by flushing pools
  • Support the in-stream vegetation
  • Provide passage for smallbodied native fish

Winter/spring high flows (20–40 ML/day) in June–November

  • Maintain or rehabilitate in-stream vegetation and disturb invasive terrestrial vegetation
  • Provide passage for smallbodied fish

Summer/autumn low flows (4–6 ML/day) in December–May

  • Maintain waterbug habitat by providing suitable depth over riffles

1 The range in flow requirements represent the target flow requirements for reaches 6 and 7.

Risk management

In preparing its seasonal watering proposal, Melbourne Water considered and assessed the risks of environmental watering and identified mitigation strategies. Program partners continually reassess risks and mitigation actions throughout the water year.

Engagement

Table 2 shows the partners, stakeholder organisations and individuals Melbourne Water consulted when preparing the Maribyrnong system seasonal watering proposal.

Seasonal watering proposals are informed by longer-term regional catchment strategies, regional waterway strategies, environmental flow studies, water management plans and other studies. These incorporate a range of environmental, cultural, social and economic perspectives and longerterm integrated catchment and waterway management objectives. For further details, refer to the Port Phillip and Western Port Regional Catchment Strategy and Melbourne Water's Healthy Waterways Strategy.

Table 2 Partners and stakeholders engaged in developing the Maribyrnong system seasonal watering proposal 

Partner and stakeholder engagement
  • Department of Environment, Land, Water and Planning 
  • Environment groups (Landcare and friends' groups, including Jacksons Creek EcoNetwork and Friends of the Maribyrnong Valley) 
  • Keilor irrigators 
  • Melbourne Water (Diversions Group) 
  • Southern Rural Water 
  • Victorian Environmental Water Holder 
  • Western Water 
  • Wurundjeri Land and Compensation Cultural Heritage Council Aboriginal Corporation