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The lower Broken Creek system includes the section of Broken Creek that flows from the confluence of Boosey Creek near Katamatite to the Murray River; and Nine Mile Creek, which is an anabranch of lower Broken Creek that flows from the East Goulburn Main Channel to below Numurkah.

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. These modifications have changed the way native animals use the creek. 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, control water quality and flush azolla as necessary.

Lower Broken Creek is operated separately to upper Broken Creek and the Broken River, because regulated water is delivered to lower Broken Creek from the Goulburn and Murray systems via the irrigation channel network, unlike upper Broken Creek and Broken River which are both supplied from Lake Nillahcootie on the 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 watering 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 blooms 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 — IVTs (from the Goulburn to the Murray) or choke bypass flows (when bypassing the Barmah choke in the Murray) — 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 the operational releases.

Traditional Owners
Storage manager
Environmental water holder

System map

Environmental watering objectives in the Lower Broken Creek

Fish icon
Protect and increase native fish populations including the threatened Murray cod, golden perch and silver perch
Platypus icon
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
Plant icon
Avoid the excessive build-up of azolla Maintain the cover and condition of native in- stream and littoral vegetation communities
Insect icon
Maintain the diversity and abundance of waterbug populations
Water icon
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 Yorta Yorta Nation Aboriginal Corporation during the planning of environmental water deliveries in the lower Broken Creek. The environmental and ecological objectives of the proposals were supported and align with the broad values of caring for Country. Goulburn Broken CMA and Yorta Yorta Nation Aboriginal Corporation will explore further opportunities to deliver environmental water to support Yorta Yorta cultural values throughout the year.

Yorta Yorta Nation Aboriginal Corporation raised concerns about the cultural damage water transfers are having on the lower Goulburn River and the Barmah Choke in addition to the ecological damage being caused. Using the lower Broken and Nine Mile Creeks for delivery of water (either environmental or consumptive) to the lower Murray River as a bypass mechanism may help reduce the risk of erosion on the Barmah Choke and lower Goulburn River and thus help to protect culturally significant values.

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 and kayaking)
  • riverside recreation and amenity (such as game hunting)
  • socio-economic benefits (such as diverters for irrigation, domestic and stock uses, and water quality including preventing algal and azolla blooms).

Recent conditions

The Goulburn Broken region had below-average rainfall and above-average temperatures for most of 2019–20. Rainfall at Numurkah during the first half of 2019–20 was just over half of the long-term average for this period, resulting in low inflows to the local catchment. Water for the environment from the Goulburn and Murray system portfolios was used in combination with operational water to meet flow targets throughout the year.

Flow in lower Broken Creek was lower than planned during winter 2019–20, due to maintenance works on the Yarrawonga Main Channel and the East Goulburn Main Channel. Consequently, fish ladders were closed in July 2019 to hold water in the system to maintain fish habitat. Some water was delivered to the creek from secondary outfall irrigation channels, but flow in reaches 3 and 4 dropped to 15 ML per day on occasions, which is well below the recommended minimum winter target of 40 ML per day.

The flow increased to 250 ML per day at the start of the irrigation season in August 2019, and the rapid increase likely cued some fish movement through the system. IVTs from the Goulburn system and Murray choke bypass flows increased flow in lower Broken Creek to 500 ML per day in late October 2019, which likely cued further fish movement and spawning and flushed azolla. The average flow at Rice’s Weir remained around 410 ML per day through summer and early autumn as operational water transfers to the Murray continued. Water for the environment was delivered in conjunction with operational deliveries from late March 2020 to maintain a flow of about 200 ML per day until the end of the irrigation season.

There is limited ecological monitoring in lower Broken Creek, but members of the Broken Environmental Water Advisory Group have reported a marked improvement in water quality since targeted environmental water deliveries started in 2010–11. The delivery of minimum low flow during the off-irrigation season provided winter foraging habitat and instream refuge areas, especially important for young-of- year fish, platypus, rakali (water rats) and turtles.

Scope of environmental planning

Table 1 Potential environmental watering actions and objectives for lower Broken Creek

Potential environmental watering action

Functional watering objective

Environmental objectives

Year-round low flow (40- 200 ML/day in reaches 3 and 4 and 40-100 ML/day in reaches 1 and 2)1

  • Provide native fish 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 cold in winter
  • Provide flowing-water habitat and avoid winter drying of weir pools for fish, vegetation, waterbugs, platypus and turtles
  • Limit suspended sediment and maintain suitable oxygen concentration
Fish iconPlatypus iconTurtle iconPlant iconInsect iconWater drop icon

Winter/spring/summer/ autumn high flow (200-250 ML/day in reaches 3 and 4 and 100-150 ML/day in reaches 1 and 2 during July to May)

  • Provide habitat for fish and support fish movement, spawning and recruitment
  • Flush and mobilise azolla and maintain oxygen levels in summer
Fish iconPlant iconWater drop icon

Winter/spring freshes (up to three freshes of 450 ML/day during July to September)

  • Flush and mobilise azolla, if it blooms
  • Trigger fish migration and movement
Fish iconPlant icon

1Intended to be delivered year-round, subject to supply constraints. Constraints may mean these flows cannot be delivered in the non-irrigation season between mid-May and mid-Augus.

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

Page last updated: 24/07/20