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 flow 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 have introduced invasive species such as arrowhead (Sagittaria graminea). 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 minimum flows throughout the year. Particular attention is given to reaches 1 and 2 during the non- irrigation season when 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. The measurement point for environmental flows in lower Broken Creek is at Rices Weir.

Some of the environmental flow targets for lower Broken Creek are partly or wholly met by operational water releases — inter-valley transfers (IVTs) from the Goulburn to the Murray or Barmah Choke bypass flows — that are delivered to meet downstream demands. These operational deliveries mainly occur during peak irrigation demand 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.

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

Maintain the diversity and abundance of waterbug populations

Maintain dissolved 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

Goulburn Broken CMA consulted with the Yorta Yorta Nation Aboriginal Corporation (YYNAC) during the planning of deliveries of water for the environment in lower Broken Creek. The following cultural values were identified for lower Broken Creek.

“The Broken Creek holds many cultural values. Common reed contained within the slack water provides important material for tools whilst 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” (YYNAC, 4 March 2021).

Yorta Yorta Nation Aboriginal Corporation continues to pursue their inherent rights to water for country to improve their spiritual, cultural, environmental, social and economic needs Yorta Yorta Whole of Country Plan 2021-2030, (YYNAC).

The environmental objectives in the lower Broken Creek seasonal watering proposal are supported by Yorta Yorta and align with their values of caring for Country. Flows have been specifically targeted to support in-stream vegetation and native fish, along with other aquatic biota. The Goulburn Broken CMA will continue to work with Yorta Yorta people to identify how the management of water for the environment can best support water for their country, enhancing cultural values.

Yorta Yorta Nation Aboriginal Corporation has raised concerns around flow regulation in all their waterways, which is having an impact on their country and cultural knowledge.

Social, recreational and economic values and uses

In planning the potential watering actions in Table 5.5.3, 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 passive recreation)
socio-economic benefits (such as consumptive water users, Goulburn-Murray Water irrigators and diverters and Goulburn Valley Water customers).

Recent conditions

The Goulburn Broken region experienced average rainfall and above-average temperatures for most of 2020-21. Unregulated flow from upper Broken Creek provided minimal contribution to lower Broken Creek throughout the season, but inflows to Goulburn and Murray storages that supply lower Broken Creek saw high-reliability entitlements reach 100 percent allocation by November and February respectively.

Flow in lower Broken Creek was restricted during winter 2020-21 due to maintenance works on the Yarrawonga Main Channel and the East Goulburn Main Channel. The flow dropped below the recommended winter target of 40 ML per day in all reaches, and fishways were closed between May and June 2020 to maintain water levels in the weir pools. Extended high flows were delivered from the start of the irrigation season in August 2020, which helped flush accumulated azolla through the system. Water for the environment was used to deliver a fresh in September 2020, to cue native fish movement. This was followed by a period of stable, high flow to optimise available habitat during the Murray cod breeding season. IVTs from the Goulburn system, Barmah Choke bypass flows and other operational transfers to the Murray system maintained an average flow of about 380 ML per day (with peaks up to 540 ML per day) in lower Broken Creek from mid-November 2020 to early autumn 2021. Water for the environment was delivered in conjunction with operational deliveries from late March 2021, to maintain a flow of about 200 ML per day until the end of the irrigation season.

Deliveries of water for the environment in lower Broken Creek were managed in line with an average climate scenario during 2020-21. All planned environmental watering actions from spring 2020 until May 2021 were partially or fully achieved, but the inability to meet the minimum winter low-flow target for the second consecutive year has potentially compromised some environmental objectives for young-of-year fish and platypus. Any channel maintenance works that prevent the delivery of minimum low-flow targets outside the main irrigation season in 2021-22 will further compromise these environmental objectives.

There is little ecological monitoring in lower Broken Creek, but members of the Broken Environmental Water Advisory Group and other community members have reported a marked improvement in water quality since targeted deliveries of water for the environment started in 2010-11. There are also anecdotal reports of improvements to the native fish population. Higher flows associated with IVTs and Murray bypass deliveries help maintain oxygen levels in the creek, but their impact on bank health is a potential concern, and it is currently being investigated.

Scope of environmental planning

Table 1 Potential environmental watering actions and objectives for 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 movement of juveniles of both species Provide habitat for turtles including protection from exposure to the cold in winter 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 frosting Reduce the stagnation of weir pools and maintain suitable oxygen concentrations
Spring/summer/autumn low flow (70-150 ML/day in reaches 1 and 2 and 200 to 250 ML/day in reaches 3 and 4 during July to May)	Provide habitat for native fish, platypus, rakali, turtles and waterbugs Support the movement and recruitment of fish Mobilise azolla and maintain oxygen levels in summer
Winter/spring fresh(es) (one to three freshes of 300-450 ML/day for one to two weeks during July to September)	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

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 adjusting weir pool levels ahead of planned maintenance work and scheduling works to minimise the duration of impacts on flow.s.

Engagement

Table 2 shows the partners and stakeholder organisations with which the Goulburn Broken CMA engaged when preparing the Broken system seasonal watering proposal.

Seasonal watering proposals are informed by longer-term plans such as regional catchment strategies, regional waterway strategies and environmental water management plans and other studies. These plans incorporate a range of environmental, cultural, social and economic perspectives and longer term integrated catchment and waterway management objectives. For further details, refer to the Goulburn Broken Regional Catchment Strategy and Goulburn Broken Waterway Strategy.

Table 2 Partners and stakeholders engaged in developing the Broken system seasonal watering proposal

Partner and stakeholder engagement
Broken Boosey Conservation Management Network Broken Creek Field Naturalists Club Goulburn Murray Landcare Commonwealth Environmental Water Office Goulburn- Murray Water Parks Victoria Moira Shire Council Individual landholders who are on the Broken Environmental Water Advisory Group Individual community members on the Broken Environmental Water Advisory Group Nathalia Angling Club Numurkah Fishing Club Taungurung Land and Waters Council Yorta Yorta Nation Aboriginal Corporation

Partner and stakeholder engagement

Broken Boosey Conservation Management Network
Broken Creek Field Naturalists Club
Goulburn Murray Landcare
Commonwealth Environmental Water Office
Goulburn- Murray Water
Parks Victoria
Moira Shire Council
Individual landholders who are on the Broken Environmental Water Advisory Group
Individual community members on the Broken Environmental Water Advisory Group
Nathalia Angling Club
Numurkah Fishing Club
Taungurung Land and Waters Council
Yorta Yorta Nation Aboriginal Corporation

Page last updated: 22/01/21