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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, which supply potable water to communities in and around Ballarat and Geelong. Lal Lal Reservoir is used to supply water to the Ballarat area. Water from Lal Lal is also delivered via the Moorabool River to She Oaks Weir to supply towns in the Geelong area.

The surrounding catchment is heavily farmed, with about three-quarters of the catchment area used for agriculture. Despite substantial extraction and many years of drought, the river still retains significant environmental values.

There are several large water storages including Lal Lal Reservoir in the upper reaches of the river. In the lower reach (between She Oaks and Batesford), there are nine private diversion weirs that are a significant barrier to fish. These barriers have increased the extent of slow-flowing habitat and reduced habitat diversity in the lower reach of the Moorabool, reducing the diversity and abundance of migratory fish in this part of the river.

The Moorabool is a water supply catchment for Barwon Water and Central Highlands Water. Releases are made for urban water supply by Barwon Water from Lal Lal Reservoir to She Oaks Weir. These releases contribute to environmental outcomes in reach 3a and 3b and allow more-efficient delivery of environmental water to reach 4. Barwon Water and Corangamite CMA work together to optimise these benefits.

Water allocated to the Moorabool River environmental entitlement is stored in Lal Lal Reservoir and includes passing flows that help maintain flows in the river. Passing flows are a significant component of annual streamflow and are important in maintaining baseflows through winter. The priority reaches for environmental water delivery are the reaches between Lal Lal Reservoir and She Oaks Weir (reaches 3a and 3b), as these are where the small amount of available environmental water can have the most beneficial impact. Environmental water delivered also provides benefits to significant flow-dependant values in reach 4 (which flows from She Oaks Weir down to the confluence with the Barwon River in Geelong).

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 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 providing flows for fish to move upstream and downstream and suitable conditions for fish to spawn
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Reshape the riverbank and riverbed and 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 provide energy, 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 streambanks 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, cultural and economic values

The Moorabool River has important social, cultural, recreational and economic values. 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 long history with the river. They have actively helped protect and restore the river, and strongly advocated the establishment of the Moorabool River Environmental Entitlement 2010.

Local Aboriginal Victorians and their Nations also have a strong connection with the waterway and place a high cultural value on it, including those represented by the Wathaurung Aboriginal Corporation (Wadawurrung).

Conditions mid-2017

High rainfall in September and October 2016 filled Lal Lal Reservoir and increased the volume of environmental water available under the entitlement from 10 percent to 100 percent full capacity. Passing flows from Lal Lal Reservoir were delivered for most of 2016. In late 2016, the reservoir was 100 percent full and spilling for a short period, which also contributed to river flows. Winter high-flow and bankfull events were achieved naturally in 2016, which allowed the Corangamite CMA to focus environmental water delivery on summer low flows and summer fresh targets in 2017.

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

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 the streambed
  • Maintain the vegetation on the riverbank
  • Trigger downstream spawning migration of adult short-finned eel and grayling
  • Maintain water quality, top up habitat refuge pools and avoid critical loss of biota

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

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

Winter/spring freshes (2–3 freshes targeting 80–162 ML/day for 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 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

Waterway managers meet communities on environmental watering regionally, although other program partners also play a role.

In each region of Victoria, community engagement on environmental watering happens when environmental watering objectives and priorities are scoped (long term and annually), when delivering environmental water, and when reporting on environmental watering results.

In the Corangamite region communities are involved in decisions about the Moorabool river and Lower Barwon wetlands. This happens through formal advisory groups including a Moorabool stakeholder advisory and the Lower Barwon community advisory committees.

Who is engaged and how

Recreational users

Through formal advisory groups, recreational user representatives (Field & Game Australia; Geelong Gun and Rod Association; VRFish) provide advice and communicate their priorities. They are informed of environmental water deliveries and provide data that assists with reporting the outcomes of environmental watering.

Field & Game Australia (Geelong branch) has been a key advocate for environmental watering, providing assistance in monitoring activities and on-ground works.

Environment groups

Through formal advisory groups, environmental groups (People for a Living Moorabool; Geelong Environment Council; Geelong Landcare Network; Environment Victoria; Geelong Field Naturalists) provide local knowledge and advocate for the environment - specifically on seasonal watering proposals and longer term Environmental Water Management Plans. Environmental groups also receive email updates during environmental water delivery.

Landholders/farmers

Through formal advisory groups, landholders (specifically those who own land with river frontage, and commercial eel fishers in the lower Barwon wetlands) provide local knowledge and advice regarding environmental watering. They are also informed of environmental water deliveries and provide data that assists with reporting on the outcomes of environmental watering.

Traditional Owners

Traditional Owners are invited to participate in engagement activities regarding the Moorabool River and the Lower Barwon wetlands.

Councils

The City of Greater Geelong and Moorabool Shire have been invited to join formal advisory groups.

General public

The Corangamite Catchment Management Authority website and media releases on environmental watering are the main mechanisms for communications and engagement with the general public on environmental watering.

The Catchment Management Authority engages with the general public on environmental watering via their website and media releases.