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The lower section of the Moorabool River between She Oaks and Batesford has nine private diversion weirs that are significant barriers to fish. These barriers have increased the extent of slow-flowing habitat and reduced habitat diversity.

The Moorabool is a water supply catchment for Barwon Water and Central Highlands Water. Releases from Lal Lal Reservoir for urban water supply contribute to environmental outcomes in reach 3a and 3b (upstream of Barwon Water’s diversion point at She Oaks) and allow more-efficient delivery of water for the environment to reach 4. Barwon Water and Corangamite CMA coordinate to make releases in tandem, where possible, to maximise these benefits.

Water allocated to the Moorabool River environmental entitlement is stored in Lal Lal Reservoir. The entitlement includes passing flows that are a significant component of annual streamflows and help maintain low flows through winter. The priority reaches for deliveries of water for the environment are between Lal Lal Reservoir and She Oaks Weir (reaches 3a and 3b, as shown in Figure 3.6.1), as that is where the small amount of available water can have the most benefit: water use is limited by both inflow to the reservoir and by a use cap specified in the entitlement. Environmental flows may also provide some benefits to flow-dependent values in the reach between She Oaks Weir and the confluence with the Barwon River.

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

Fish icon
Maintain self-sustaining populations of native fish (in particular short-finned eel, Australian grayling, spotted galaxias and tupong)
Landscape icon
Maintain physical habitat diversity
Platypus icon
Restore self-sustaining breeding populations of platypus and support the dispersal of juveniles
Plant icon
Maintain riparian vegetation communities.

Maintain in-stream macrophyte communities.
Insect icon
Maintain diverse waterbug communities
Water icon
Improve water quality

Environmental values

Despite substantial extraction and many years of drought, the Moorabool River retains significant environmental values. The 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 stream bank shrubland and riparian woodland ecological vegetation communities. Platypus, rakali (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.

Recent conditions

The Moorabool system typically behaves as a boom-orbust system and is very dependent on seasonal rainfall. The catchment has experienced dry conditions over the past two years, and the environment’s share of inflows has been low. High importance was therefore placed on maintaining low flows during summer near Batesford, where, without environmental flows, the river can stop flowing.

In 2019, the VEWH in partnership with Central Highlands Water, Barwon Water and the Corangamite CMA, secured additional water to use in the Moorabool River to mitigate the effects of drought. The additional water was from oneoff transactions that allowed the delivery of priority watering actions including an autumn fresh, which connected habitats along the river and improved water quality. As in previous years, the coordination of environmental flows with releases of water for operational or consumptive purposes greatly increased the efficiency of environmental watering. The ability to piggyback on operational releases means that less allocation of water for the environment is needed to meet target flows.

Scope of environmental watering

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

Potential environmental watering action1

Functional watering objective

Environmental objective

Summer low flows (> 5 ML/day during December to May)

  • Maintain pool and riffle habitats for fish, macroinvertebrates, platypus
    and submerged aquatic vegetation
  • Improve water quality in refuge pools
Fish iconPlatypus iconPlant iconInsect iconWater drop icon 

Winter low flows (> 5 ML/day during June to
November)

  • Maintain a clear flow path and allow fish movement throughout the reach
  • Control intrusions by terrestrial vegetation into the stream bed

Fish iconPlant icon

Spring fresh (one to two freshes of 80 ML/day for five days during September to November)

  • Trigger upstream migration of juvenile galaxias, tupong, short-finned eel
    and grayling
  • Provide connectivity between channels and pools to support fish
    movement
  • Scour biofilms and algae from stream bed and transport organic matter

Fish iconMountain iconsInsect icon

Winter fresh (80 ML/day for five days during May to August)

  • Allow fish and platypus to move through the reach and maintain access to habitat
  • Trigger downstream spawning migration of adult tupong
  • Scour biofilms and algae from the stream bed and transport organic matter
  • Promote the growth and recruitment of native riparian vegetation including woody shrubs, and promote strong vegetation zonation on the banks

Fish iconMountain iconsPlatypus iconPlant iconInsect icon

Autumn fresh (60 ML/day for five days during April to May)

  • Encourage downstream spawning migration of Australian grayling and
    short-finned eel
  • Allow fish and platypus movement through the reach and maintain
    access to habitat
  • Flush silt and scour biofilms and algae from the stream bed
  • Water the fringing vegetation

Fish iconMountain iconsPlatypus iconPlant iconInsect icon

Summer fresh (one to two freshes of 30–60 ML/day for three to five days during January to March)

  • Flush silt and scour biofilms and algae from the stream bed
  • Water the fringing vegetation

Fish iconMountain iconsPlant iconWater drop icon

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

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
  • Australian Platypus Conservancy
  • Geelong Landcare Network
  • Local community groups
  • Moorabool Stakeholder Advisory Committee
  • People for a Living Moorabool
  • Individual landholders who are on the Moorabool Stakeholder Advisory Committee
  • Barwon Water
  • Central Highlands Water
  • Department of Environment, Land, Water and Planning
  • Parks Victoria
  • Southern Rural Water
  • Victorian Environmental Water Holder
  • Individual recreational users who are on the Moorabool Stakeholder Advisory Committee
  • Wathaurung Aboriginal Corporation