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The Moorabool River is a tributary of the Barwon River. It flows south from the Central Highlands between Ballarat and Ballan to join the Barwon River at Fyansford just north of Geelong. The Moorabool River is a highly regulated catchment with major storages that include Lal Lal, Moorabool and Bostock reservoirs. Despite substantial extraction and many years of drought, the river retains significant environmental values.

The Moorabool River and its tributaries continue to be an important place for Traditional Owners and their Nations. The Registered Aboriginal Party (RAP) in the region is the Wathaurung Aboriginal Corporation. RAP representatives were engaged in the preparation of the Moorabool system seasonal watering proposal.

Water for Victoria identifies the Moorabool River as a priority for restoration. The Living Moorabool project includes activities to protect and improve riparian land and to remove fish barriers in the Moorabool River catchment. Complementary water management activities such as these are needed to optimise the environmental outcomes achievable with environmental flows.

Storage operator
Environmental water holder

System map

Moorabool System
Grey river reaches have been included for context. The numbered reaches indicate where relevant environmental flow studies have been undertaken. Coloured reaches can receive environmental water.

Environmental watering objectives in the Moorabool River

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Maintain remnant vegetation communities including a range of macrophytes (large water plants) within the river channel; these plant communities provide shade and food for organisms further up the food chain
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Protect and increase native fish populations including Australian grayling, southern pygmy perch, spotted galaxias, tupong and shortfinned eel by maintaining habitat throughout the catchment and by providing flows for fish to move upstream and downstream as well as suitable conditions for fish to spawn
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Flush silt and scour biofilms in the stream bed, scour pools and maintain channel form to ensure fish and other water animals have a range of habitat pools and places to shelter
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Improve water quality during the year, particularly during summer
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Maintain a wide range and high biomass of waterbugs to break down dead organic matter and support the river’s food chain

Environmental values

The Moorabool River is home to native fish species including the Australian grayling, river blackfish, Australian smelt, flat-headed gudgeon, southern pygmy perch, short-finned eel, spotted galaxias, and tupong. The system contains extensive areas of endangered remnant vegetation including streambank shrubland and riparian woodland ecological vegetation communities. Platypus, water rats and a range of waterbugs are also present. The Moorabool River flows into the Barwon River, connecting it to the Ramsar-listed lower Barwon wetlands.

Social and economic values

The Moorabool River has important social, cultural, recreational and economic values. It supplies potable water to large communities in and around Ballarat and Geelong. The surrounding catchment is heavily farmed, with about three-quarters of the catchment area used for agriculture. Its confined valley provides spectacular scenery and its reaches include parks, picnic sites, lookouts, swimming holes, fishing and camping spots and historic bridges. Many local people in the region have a connection to and a long history with the river. They have been active in protecting and restoring the river, and are strong advocates for the Moorabool River Environmental Entitlement 2011.

Conditions 2018

High rainfall in 2016 filled Lal Lal Reservoir and ensured strong allocations against the environmental entitlement for the start of the 2017–18 water year. Water for the environment was used to deliver a winter/spring fresh, winter/spring low flow, two summer freshes and summer low flows.

Monitoring as part of the Victorian Environmental Flows Monitoring and Assessment Program (VEFMAP) indicates that in-stream and fringing vegetation along the Moorabool River has benefited from flow management and that freshes have been sufficient to eradicate many exotic species.

While passing flows were delivered for all of 2017 and into the early months of 2018, dry summer/autumn conditions meant there were reduced or no passing flows from Lal Lal Reservoir. Water for the environment provided the only flow downstream of Lal Lal Reservoir from late summer and into autumn.

As a response to the continued dry conditions in autumn, the duration of summer low flows was extended to prevent flows ceasing. This meant that water use exceeded the planned 2,500 ML for the year. The environmental entitlement allows for this greater use; a maximum 7,500 ML can be used in any consecutive three years, and water use in the previous two years totalled 2,205 ML. However, the decision to use extra water in 2017–18 will potentially restrict the volume of water that can be delivered in 2018–19 and 2019–20.

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for the Moorabool system

Potential environmental watering1

Environmental objectives

Summer/autumn low flows (5–20 ML/day in December–May)

  • Maintain pool and riffle habitat for fish, waterbugs, platypus and submerged aquatic vegetation
  • Maintain water quality

Winter/spring low flows (10–86 ML/day in June–November)

  • Allow fish movement throughout the system
  • Restrict spread of land-based vegetation into the river channel

Summer/autumn freshes (1–2 freshes targeting 30–60 ML/day for 3–5 days in December–May)

  • Allow fish and platypus movement and maintain access to habitat 
  • Flush silt and scour biofilms and algae from stream bed 
  • Maintain vegetation on the riverbank 
  • Trigger downstream spawning migration of adult short-finned eel and Australian grayling 
  • Maintain water quality, top-up refuge pools and avoid critical loss of biota

Winter/spring fresh (1 fresh targeting 80–162 ML/day for up to 10 days in May– November)

  • Allow fish and platypus movement and maintain access to habitat 
  • Trigger downstream spawning migration of adult tupong and upstream migration of juvenile galaxias, tupong, short-finned eel and Australian grayling 
  • Flush silt and scour biofilms and algae from the streambed and transport organic matter 
  • Increase the growth and recruitment of native riparian vegetation including woody shrubs and maintain vegetation zonation on the banks

1 The target reaches for environmental watering are reach 3a, 3b and 4 of the Moorabool system unless otherwise stated.

Risk management

CMA 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 and stakeholder organisations with which Corangamite CMA engaged when preparing the Moorabool 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 Corangamite Regional Catchment Strategy and the Corangamite Waterway Strategy.

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

 

Partner and stakeholder engagement
  • Barwon Water 
  • Central Highlands Water 
  • Department of Environment, Land, Water and Planning 
  • Moorabool Stakeholder Advisory Committee (with representatives of People for a Living Moorabool, Geelong Landcare Network, Southern Rural Water, Central Highlands Water, Parks Victoria, Barwon Water, the Victorian Environmental Water Holder and the local community) 
  • Parks Victoria 
  • People for a Living Moorabool and other local community groups 
  • Southern Rural Water 
  • Victorian Environmental Water Holder 
  • Wathaurung Aboriginal Corporation