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The lower section of Moorabool Yulluk (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 system 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 (above 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 optimise these benefits.

Water allocated to the Moorabool Yulluk (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 inflows 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.

Traditional Owners
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

Landscape icon
Maintain channel form and processes

Maintain physical habitat diversity
Platypus icon
Maintain and improve a self-sustaining breeding population of platypus and support the dispersal of juveniles and the movement of adults
Plant icon
Maintain in-stream macrophyte communities Maintain streamside vegetation communities and promote recruitment
Insect icon
Maintain the abundance and diversity of waterbug communities
Water icon
Maintain water quality

Prevent hypoxic blackwater events
Fish icon
Improve and increase the distribution, abundance and diversity of migratory species (tupong, short-finned eel, common galaxias, spotted galaxias, short-headed lamprey and Australian grayling)

Maintain and increase the distribution, abundance and diversity of non-migratory species (flat-headed gudgeon, Australian smelt, southern pygmy perch and river blackfish)

Environmental values

Moorabool Yulluk (Moorabool River) is a highly flow-stressed system, but it does retain 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 also contains extensive areas of endangered remnant vegetation including streambank shrubland and streamside woodland ecological vegetation communities. Platypus, rakali (water rats) and a range of waterbugs are also present. Moorabool Yulluk (Moorabool River) flows into the Barwon River, connecting it to the Ramsar-listed lower Barwon wetlands.

Recent conditions

Rainfall in the Moorabool system catchment was close to the long-term average throughout most of 2020-21, but above average in late winter to early spring and during summer. Lal Lal Reservoir filled and spilled in early October 2020, when each entitlement holders total share of reservoir capacity was reached.

Water for the environment was used to help meet target low flow in early winter, but natural catchment inflows dominated flow patterns through late winter and spring. The natural spill at Lal Lal Reservoir in October 2020 delivered a peak flow of 1,040 ML per day at Morrison’s gauge, which was sufficient to connect low-lying parts of the floodplain, support channel-forming geomorphological processes and provide migration triggers for native fish. Total monthly rainfall over January 2021 contributed significantly to catchment inflows, delivering a natural fresh of 50 ML per day earlier in the month and again in early February.

These and other associated rain events helped meet many of the recommended summer/autumn freshes. Summer/autumn low- flow targets were largely met with a combination of passing flows and operational water transfers, with limited amounts of water for the environment used to make up deficits only where required.

Environmental watering in the Moorabool system was managed according to an average climate scenario throughout 2020-21, and all planned watering actions were met. About 2,100 ML was delivered in 2020-21, which ensures water availability of about the same volume or more could be delivered next year depending on catchment conditions and inflows.

Traditional Owner cultural values and uses

The Wadawurrung are the Traditional Owners of the land of Moorabool Yulluk (Moorabool River) and parts of the Barwon, Leigh and Yarrowee rivers.

Wadawurrung Traditional Owners have a strong connection to the river and place high cultural value on Moorabool Yulluk. They are a key partner in advocating for additional water recovery to help support environmental outcomes and cultural water objectives.

In 2020, the Wadawurrung Traditional Owners released Paleert Tjaara Dja – Let’s make Country good together 2020 – 2030Wadawurrung Country Plan. Waterways, rivers, estuaries and wetlands – Yulluk – are identified as key values to look after.

In 2019, the Wadawurrung partnered with Corangamite CMA to complete an environmental flows study for the upper Barwon, Yarrowee and Leigh rivers. Environmental flows studies are essential technical references for river managers, which identify the types of flows needed to support environmental and cultural values in a river system. The cultural values identified in the flows study apply to all waterways within Wadawurrung Country, including Moorabool Yulluk (Moorabool River). The values include:

  • significant aquatic species such as Buniya (eels), Ware-up (river blackfish), Tark (common reed) and Bal-yun (cumbungi) which are traditional food, materials or medicinal sources
  • waterway confluences and deep pools, which are places for meeting, ceremonies and trade and mark clan boundaries.

Social, recreational and economic values and uses

In planning the potential watering actions in Table 1, Corangamite CMA considered how environmental flows could support values and uses including:

  • water-based recreation (such as camping, fishing, kayaking and swimming)
  • riverside recreation and amenity (such as birdwatching, bushwalking, camping, picnicking and lookouts)
  • community events and tourism
  • socio-economic benefits (such as domestic stock users).

If the timing or management of planned environmental flows may be modified to align with a community benefit, this is acknowledged in Table 1 with the following icon.

Camping icons

Watering planned to support peaks in visitation (e.g. camping or other public activities on long weekends or school holidays)

Summer/autumn freshes provide a freshening flow in Moorabool Yulluk (Moorabool River) and are planned to coincide with school holidays and public holidays where possible. These flows improve opportunities for riverside and water-based recreation, in particular camping and fishing.

Scope of environmental watering

Table 1 Potential environmental watering actions, expected watering effects and associated environmental objectives for Moorabool Yulluk (Moorabool River)

Potential environmental watering action

Expected watering effects

Environmental objectives

Winter/spring low flow (10-60 ML/day continuous from June to November)

  • Maintain in-stream vegetation
  • Maintain connectivity and allow fish movement through the reach
  • Reduce intrusion by terrestrial vegetation into the stream bed
Fish iconPlant icon

Winter/spring fresh(es) (one to three freshes of 80-162 ML/day for five days during June to November)

  • Maintain pool and riffle habitats and provide connectivity to support fish and platypus movement through the reach
  • Trigger downstream spawning migration of tupong (May-August) and upstream migration of juvenile Turrpurt (galaxias), tupong, Buniya (short-finned eel) and Australian grayling (September-November)
  • Provide flow variability to maintain species diversity of the fringing vegetation and promote the growth and recruitment of streamside vegetation
  • Flush silt, scour pools and remove biofilms from hard substrates and the stream bed to maintain waterbug communities and transport organic matter to prevent blackwater events

Fish iconPlant iconPlatypus iconMountain iconsInsect iconWater drop icon

Summer/autumn low flow (5-10 ML/day continuous from December to May)

  • Maintain pool and riffle habitat for fish, waterbugs platypus and submerged aquatic vegetation
  • Maintain water quality for biota by reducing periods of low oxygen, high temperature and high electrical conductivity

Fish iconMountain iconsInsect iconPlant iconPlatypus iconWater drop icon

Summer/autumn fresh(es) (one to three freshes of 30-60 ML/day for three to five days from December to May)

Camping icons

  • Trigger downstream spawning migration of adult Buniya (short-finned eel) (January-February), tupong (May-August), Australian grayling (April-May) and short-headed lamprey
  • Maintain pool and riffle habitat and the condition of streamside vegetation, and promote recruitment
  • Allow fish and platypus to move through the reach to access habitat
  • Flush silt and scour biofilms and algae from the stream bed and substrates to improve habitat quality for waterbugs
  • Maintain water quality for biota by reducing periods of low oxygen, high water temperature and salinity

Fish iconMountain iconsPlatypus iconPlant iconInsect iconWater drop icon

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
  • Barwon Water
  • Central Highlands Water
  • Department of Environment, Land, Water and Planning - Water and Catchments
  • Southern Rural Water
  • Parks Victoria
  • Landholders on the Moorabool Stakeholder Advisory Committee
  • Recreational users on the Moorabool Stakeholder Advisory Committee
  • Wathaurung Aboriginal Corporation

Page last updated: 22/01/21