VEWH - Moorabool River

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.

Water allocated to the Moorabool River environmental entitlement is stored in Lal Lal Reservoir. The entitlement references passing flow, a significant component of annual streamflow and helps maintain a low flow through winter. Water use is limited by inflows to the reservoir and by a use cap specified in the entitlement. 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. Environmental flows may also benefit flow-dependent values in the reach between She Oaks Weir and the confluence with the Barwon River.

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 the Corangamite CMA coordinate operational and environmental releases, where possible, to optimise these benefits.

Proportion of water entitlements in the Moorabool River held by private users, water corporations and environmental water holders on 30 June 2020

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

Maintain channel form and processes

Maintain physical habitat diversity

Maintain and improve a self-sustaining breeding population of platypus and support the dispersal of juveniles and the movement of adults

Maintain in-stream macrophyte communities

Maintain streamside vegetation communities and promote recruitment

Maintain the abundance and diversity of waterbug communities

Maintain water quality

Prevent hypoxic blackwater events

Increase the distribution, abundance and diversity of migratory species (tupong, short-finned eel, common galaxias, spotted galaxias, short-headed lamprey and Australian grayling)

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

Environmental values

The Moorabool River is a highly flow-stressed system, but it 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 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. The Moorabool River flows into the Barwon River, connecting it to the Ramsar-listed lower Barwon wetlands.

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 Moorabool Yulluk (Moorabool River) and place high cultural value on it. The Wadawurrung Traditional Owners Aboriginal Corporation (WTOAC) is a key partner in advocating for additional water recovery to help support a healthy river and associated cultural water objectives.

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

In 2019, the WTOAC partnered with the 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 that identify the types of flows needed to support environmental values in a river system. The 2019 flows study also identified cultural values in all waterways within Wadawurrung Country, including Moorabool Yulluk (Moorabool River).

The values include:

significant aquatic species such as wad-dirring/peridak (platypus), buniya (short-finned eel), turrpurt (tupong), ware-up (river blackfish), tark (common reed) and bal-yan (bull rush), which are traditional sources of food, materials and medicines
waterway confluences and deep pools, which are places for meeting, ceremonies, trade and marking clan boundaries.

In early 2023, a meeting was held between the Corangamite CMA and WTOAC to discuss proposed 2023-24 environmental flows in the Moorabool Yulluk (Moorabool River). WTOAC supports the proposed environmental flows and may partner with the Corangamite CMA to coordinate the delivery of summer/autumn freshes and some winter/spring freshes to coincide with cultural events.

Social, recreational and economic values and uses

In planning the potential environmental watering actions in Table 3.6.1, the 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.

If the timing or management of planned environmental flows may be modified to align with a community benefit, this is acknowledged in Table 3.6.1 with the following icon.

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 the Moorabool River and are planned to coincide with school and public holidays where possible. This freshened flow improves riverside and water-based recreation opportunities, particularly camping and fishing.

Scope of environmental watering

The term ‘environmental watering’ refers to the active delivery of water for the environment to support particular environmental objectives by altering the flow in a river or the water level in a wetland. While other terms are also used to describe the delivery of water for the environment, ‘environmental watering’ is deliberately used here and in seasonal watering statements to ensure consistency in the legal instruments that authorise the use of water for the environment in Victoria.

Table 3.6.1 describes the potential environmental watering actions in 2023-24, their expected watering effect (that is, the intended physical or biological effects of the watering action) and the longer-term environmental objectives they support. Each environmental objective relies on one or more potential environmental watering actions and their associated physical or biological effects.

Table 3.6.1 Potential environmental watering actions, expected watering effects and associated environmental objectives for the Moorabool system

Potential environmental watering action	Expected watering effects	Environmental objectives
Winter/spring low flow (5-60 ML/day during June to November)	Maintain in-stream vegetation Maintain connectivity and allow fish movement through the reach Maintain pool and riffle habitat for platypus and native fish Reduce intrusion by terrestrial vegetation into the stream bed
Autumn/winter/spring freshes (two to three freshes of 80-90 ML/day for five to 10 days during May 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) Temporarily inundate the lower part of the riverbank 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
Summer/autumn low flow (5-40¹ ML/dayduring December to May)	Maintain refuge pools and riffle habitat for fish, waterbugs and platypus and submerged aquatic vegetation Maintain water quality for aquatic life by reducing periods of low oxygen, high temperature and high salinity
Small summer/autumn fresh (one fresh of 30-60 ML/day for three days during February to March)	Maintain pool and riffle habitat and the condition of streamside vegetation and water-fringing marginal zone vegetation, and promote recruitment Allow fish movement through the reach
Large summer/autumn fresh(es) (one to two freshes of 60-80 ML/ day for five days during December to May)	Trigger the 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 by reducing periods of low oxygen, high water temperature and salinity
Year-round freshes (trigger-based, of 30 ML/ day for three days) Triggers: oxygen below 5 mg/L; electrical conductivity above 10,000 μs/cm; water temperature above 25°C	Maintain water quality by reducing periods of low oxygen, high water temperature and salinity

Page last updated: 01/07/22