VEWH - Lower Broken Creek

Lower Broken and Nine Mile creeks have been regulated for over a century. Before regulation, the creeks would have had most of their flow in winter/spring and contracted to isolated pools or dried out during summer/autumn. The adjacent floodplain would have also flooded regularly. The creeks now have numerous weirs that maintain a relatively constant water level from mid-August until mid-May to support irrigated agriculture and little flow during the non-irrigation season. These modifications have changed the way native species use the creek and favour invasive species (such as arrowhead). Previously, native fish would have moved into the creek when it was flowing and returned to the Murray River as it dried. Both creeks now provide year-round habitat for native fish, and fish passage structures allow fish to move between weir pools. Water for the environment is used to support these permanent fish habitats by providing flows to trigger fish movement and support fish passage, encourage the growth of native plants, promote in-stream productivity, control water quality and flush the water fern azolla as necessary.

Regulated water is delivered to lower Broken Creek from the Goulburn and Murray systems via the irrigation channel network. Lower Broken Creek is operated separately from upper Broken Creek and Broken River, which are both supplied from Lake Nillahcootie on upper Broken River.

Water for the environment can be provided to lower Broken Creek from the Goulburn system through the East Goulburn Main Channel and from the Murray system through the Yarrawonga Main Channel. Water is released into lower Broken Creek from several irrigation regulators along the length of lower Broken Creek. The main priority for environmental flows in the lower Broken Creek system is to maintain a minimum flow throughout the year to maintain suitable habitat for native fish. Particular attention is given to reaches 1 and 2 during the non-irrigation season when the flow can stop. The next priority is to deliver freshes in winter/spring to trigger fish movement and spawning, maintain water quality and manage azolla accumulations in reaches 3 and 4. Rices Weir is the measurement point for environmental flows in lower Broken Creek.

Some of the environmental flow targets for lower Broken Creek are partly or wholly met by operational water releases: intervalley transfers (IVTs) from the Goulburn to the Murray or Barmah Choke bypass that are delivered to meet downstream demands. These operational deliveries mainly occur during peak irrigation demand periods between spring and autumn. Water for the environment may be used to supplement these operational releases and to deliver recommended flow components that are not met by operational releases.

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

System map

Environmental watering objectives in the Lower Broken Creek

Protect and increase native fish populations, including the threatened Murray cod, golden perch and silver perch

Protect platypus populations, particularly outside the irrigation season

Protect rakali (water rat) populations, particularly outside the irrigation season

Protect turtle populations, particularly outside the irrigation season

Avoid the excessive build-up of azolla

 Increase the cover and condition of native in-stream and littoral vegetation communities

Increase the diversity and abundance of waterbug populations

Maintain oxygen levels suitable for aquatic animals

Environmental values

Lower Broken Creek and Nine Mile Creek support a diverse and abundant native fish community, including the threatened Murray cod, golden perch, silver perch, unspecked hardyhead and Murray-Darling rainbowfish.

Sections of lower Broken and Nine Mile creeks have been reserved as state park and natural feature reserves. The associated floodplain and wetland habitats support box-dominated grassy woodland communities and numerous species of state and national conservation significance, including river swamp wallaby grass and the Australasian bittern.

Traditional Owner cultural values and uses

Lower Broken Creek flows on Yorta Yorta Country.

Each year, the Goulburn Broken CMA meets with the Yorta Yorta Nation Aboriginal Corporation to discuss water for the environment in lower Broken Creek. A meeting was held in early 2023 to discuss 2023-24 environmental watering priorities. The planned environmental flows for 2023-24 in the lower Broken Creek are supported by the Yorta Yorta Nation Aboriginal Corporation. The flows will support in-stream vegetation and native fish, along with other aquatic plants and animals. The Goulburn Broken CMA will continue to work with Yorta Yorta People to identify how the management of water for the environment can better support cultural values.

In 2021, the Yorta Yorta Nation Aboriginal Corporation provided the following statement about the cultural values of the Broken River system including lower Broken Creek: “The Broken River and Broken Creek hold many cultural values. Common reed contained within the slack water provides important material for tools while also providing refuge for culturally important fish species (large and small-bodied). The creek also has significant stands of old-growth river red gum containing important habitat and exhibiting scars made from carving out canoes and coolamons.” The Yorta Yorta Nation Aboriginal Corporation has raised concerns about flow regulation in all their waterways, which is affecting their Country and cultural knowledge.

The Yorta Yorta Nation Aboriginal Corporation continues to pursue the Yorta Yorta People’s inherent rights to water for Country. Rights to water will improve their spiritual, cultural, environmental, social and economic needs, in line with the Yorta Yorta Whole-Of-Country Plan 2021-2030.

Social, recreational and economic values and uses

In planning the potential environmental watering actions in Table 5.5.3, the Goulburn Broken CMA considered how environmental flows could support values and uses, including:

water-based recreation (such as canoeing, fishing, game hunting and kayaking)
riverside recreation and amenity (such as aesthetic and amenity values that are particularly important for the community’s mental health and wellbeing during dry periods and for passive recreation)
community events and tourism
socioeconomic benefits (such as consumptive water users, Goulburn-Murray Water irrigators and diverters and Goulburn Valley Water customers).

Scope of environmental watering

The term ‘environmental watering’ refers to the active delivery of held environmental water to support particular environmental objectives by altering the flow in a river or the water level in a wetland. While other terms are sometimes used to describe the delivery of environmental water, ‘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 5.5.3 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 5.5.3 Potential environmental watering actions, expected watering effects and associated environmental objectives for the lower Broken Creek

Potential environmental watering action	Expected watering effects	Environmental objectives
Winter low flow (20-40 ML/day during May to August)¹	Provide native fish with passage through fish ladders Provide suitable foraging habitat for platypus and rakali (water rats), and support the conditioning of females in preparation for the breeding season Provide habitat for turtles, including protection from exposure during their winter dormancy Provide flowing-water habitat and avoid winter drying of weir pools for fish, vegetation, waterbugs, platypus and turtles Maintain water over submerged aquatic plants so they are protected from drying and frost Reduce the stagnation of weir pools
Spring/summer/autumn low flow (70-250 ML/ day in reaches 1 and 2 and 200-450 ML/day in reaches 3 and 4 during August to May)	Provide habitat for native fish, platypus, rakali (water rats), turtles and waterbugs Support the movement and recruitment of fish Maintain oxygen levels in summer Additional benefits when delivered from December to February (at 250-450 ML/day): mobilise azolla and increase oxygen levels during high-risk periods
Winter/spring fresh(es) (one to three freshes of 300-450 ML/day for one to two weeks during July to November)	Flush and mobilise azolla if it has accumulated to maintain water quality Trigger the movement and spawning of fish Encourage the germination and growth of littoral and in-stream vegetation Reduce the stagnation of weir pools

¹This flow may be difficult to achieve when channel maintenance work is being completed. If maintenance work is required, waterway managers will work with the storage manager to minimise impacts where possible. Possible mitigation actions include closing fishways to maintain water in weir pools and scheduling works to minimise the duration of impacts on flow.

Page last updated: 01/12/22