Upper Barwon River

The operation of the West Barwon Reservoir regulates flows in the upper Barwon River. Water can be released directly from the reservoir into the west branch or into the east branch via a diversion tunnel. The junction of the two branches is near Boundary Creek. Downstream of the reservoir, operational water can be diverted into the Wurdee Boluc inlet channel, a 57 km concrete-lined channel that transfers water to Wurdee Boluc Reservoir.

Barwon Water releases passing flow in the order of 1-5 ML per day in both the upper east and west branch from the West Barwon Reservoir. These releases may increase to 15 ML per day in September in a wet year. When the reservoir holds more than 40,000 ML, all the natural flow is passed down the east branch between January and March. Flood spills from the reservoir and natural inflows from unregulated and regulated tributaries add to the passing flow in the west branch. Regulated and unregulated tributaries add to the passing flow in the east branch.

The Upper Barwon River Environmental Entitlement 2018 enables water for the environment to be made available from the West Barwon Reservoir. The entitlement provides an average of 1,000 ML per year and up to 2,000 ML of the total storage capacity at full supply. Water for the environment was first delivered to the upper Barwon River in 2018-19. The current entitlement provides only enough water to meet the highest-potential environmental watering actions in the upper Barwon east branch (reach 4) and the upper Barwon west branch (reach 3) under particular climatic conditions.

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

System map

Environmental watering objectives in the Upper Barwon River

Maintain the abundance of platypus populations

Maintain the abundance of waterbugs as a food source for fish, frog and platypus populations

Maintain water quality for native fish, waterbugs, aquatic vegetation and other water-dependent animals

Maintain the abundance of migratory fish species, including short-finned eels, Australian grayling and tupong

Maintain the abundance of resident freshwater fish, including several species of galaxias, Australian smelt, big-headed gudgeon, Yarra pygmy perch, southern pygmy perch and river blackfish

Maintain the condition and extent of in-stream vegetation to provide structural habitat for waterbugs and various fish species

Maintain the condition, extent and diversity of emergent macrophyte vegetation and streamside vegetation to provide structural habitat and stabilise the channel and lower banks

Environmental values

The upper Barwon River is home to native fish species, including the Australian grayling, river blackfish, short-finned eel, southern pygmy perch, Australian smelt and various galaxias. The system retains some submerged aquatic vegetation, undercut banks, overhanging vegetation and riffle-pool sequences, which provide important habitat for fish and other aquatic animals.

Long-term environmental objectives for the upper Barwon system are based on delivering watering actions recommended
in the Upper Barwon, Yarrowee and Leigh rivers Environmental FLOWS Study. These include improving the breeding
and recruitment of various fish, platypus and macroinvertebrate species, as well as improving the condition, extent and diversity of in-stream, emergent, streamside and floodplain vegetation. However, due to the limited entitlement to water for the environment and channel constrictions, the recommended flow magnitudes have been modified to less than the known channel constraints. It is unlikely that there will be significant improvements in the river’s ecological condition by delivering the watering actions in this plan. Until works are carried out to address channel constraints and other factors (such as unrestricted livestock access and weed infestation), this plan’s potential environmental watering actions aim to maintain the current ecological condition and prevent cease-to-flow events.

Traditional Owner cultural values and uses

The reaches of the Barwon River that can be most influenced by water delivered from the West Barwon Reservoir sit on Eastern Maar Country.

In February 2020, the Eastern Maar Aboriginal Corporation (EMAC) received Registered Aboriginal Party (RAP) status under the Victorian Aboriginal Heritage Act 2006 over a large portion of land in south-west Victoria, including the Barwon River upstream of Winchelsea. In 2023 Eastern Maar gained formal recognition of their rights under the Commonwealth Native Title Act 1993 for over half of the RAP area, adding to initial recognition in 2011 under the Native Title Act, though further areas remain in negotiation. Native Title determination acknowledges Eastern Maar’s ongoing connection and intrinsic relationship to Country across south-west Victoria, including parts of the Barwon River catchment.

Eastern Maar obligations to Country and objectives for Country are described in the Eastern Maar Country Plan Meerreengeeye Ngakeepoorryeeyt. Eastern Maar assertions for parreeyt (water) are further documented in Eastern Maar’s Nation Statement (Water is Life: Traditional Owner Access to Water Roadmap 2022).

In early 2023, a meeting was held between the Corangamite CMA and EMAC to discuss proposed 2023-24 environmental flows in the upper Barwon River. EMAC also reviewed and provided feedback about the Corangamite CMA’s upper Barwon seasonal watering proposal, which outlined proposed environmental flows for the year ahead.

The Corangamite CMA is also working with Wadawurrung Traditional Owners Aboriginal Corporation (WTOAC) to understand opportunities to provide for cultural values and uses and other aspirations for the management of water for the environment in the Barwon River downstream of Winchelsea, on Country where WTOAC holds Registered Aboriginal Party status. In early 2023, the Corangamite CMA met with WTOAC to discuss environmental flows management in the Barwon River.

EMAC and WTOAC have formal plans for how to heal Country in the region, and the Corangamite CMA continues to work with them to identify their cultural objectives and associated values and uses that align with environmental flows.

Social, recreational and economic values and uses

In planning the potential environmental watering actions in Table 3.7.1, the Corangamite CMA considered how environmental flows could support values and uses, including:

water-based recreation (such as canoeing, kayaking, swimming and fishing, particularly for river blackfish)
riverside recreation and amenity (such as birdwatching, camping and walking)
socioeconomic benefits (such as for diverters for stock needs and domestic use: water levels and water quality can rely on the delivery of water for the environment, particularly in summer).

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 3.7.1 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 environmental objectives they support. Each environmental objective relies on one or more potential environmental watering actions and their associated physical or biological effects.

Table 3.7.1 Potential environmental watering actions, expected watering effects and associated environmental objectives for the upper Barwon River

Potential environmental watering action	Expected watering effects	Environmental objectives
Upper Barwon River (targeting reach 3 – west branch)
Winter/spring low flow (3-30 ML/day during June to November)	Maintain permanent water in the channel/pools to provide habitat to support resident and migratory fish, platypus and waterbugs With a low flow of 30 ML/day: maintain an adequate depth of permanent water in the channel to promote the recruitment of aquatic and streamside plants and to limit the encroachment of terrestrial species provide minimum velocity to mix and flush pools
Summer/autumn low flow (3-30 ML/day during December to May)
Upper Barwon River (targeting reach 4 – east branch)
Winter/spring low flow (1-9 ML/day during June to November)	Maintain an adequate depth of permanent water in the channel and pools to provide habitat to support resident and migratory fish, platypus and waterbugs Maintain an adequate depth of permanent water in the channel to promote the recruitment of aquatic and streamside plants and to limit the encroachment of terrestrial species Provide sufficient flow velocity to mix pools
Summer/autumn low flow (0.5-5 ML/day during December to May)	Maintain an adequate depth of permanent water in the channel/pools to provide habitat to support resident and migratory fish, platypus and waterbugs Reduce encroachment by terrestrial plants into the aquatic zone Provide minimum velocity to mix pools
Summer/autumn freshes (two to three freshes, of 6-9 ML/day for two days during December to May)	Increase the water depth in the channel and pools to provide habitat to support resident and migratory fish, platypus and waterbugs Provide a mosaic of wetted areas to improve emergent and streamside vegetation Provide minimum velocity to mix pools With freshes of 9 ML/day: provide longitudinal connectivity where the water depth exceeds 0.2 m over riffles to allow platypus to move between pools to breed, feed and find new habitats

Page last updated: 01/07/22