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Lake Nillahcootie has a storage capacity that is about half the mean annual flow of its upstream catchment, so it fills in most years. The operation of Lake Nillahcootie has modified the river’s natural flow pattern: winter/spring flow is less than natural because a large proportion of inflow is harvested, while summer/autumn flow is higher than natural because water is released to meet downstream irrigation demands. These impacts are most pronounced in the reach between Lake Nillahcootie and Hollands Creek. Below Hollands Creek, the river retains a more natural flow pattern, due to flows from unregulated tributaries. The catchment has been extensively cleared for agriculture including dryland farming (such as livestock grazing and cereal cropping) and irrigated agriculture (such as dairy, fruit and livestock).

Water is released from Lake Nillahcootie to meet downstream demand and minimum flow requirements specified under the bulk entitlement for the Broken River system. Releases from storage may be less than 30 ML per day as tributary inflows immediately below the storage (such as from Back Creek) can supply much of minimum-flow requirements specified in the bulk entitlement.

Upper Broken Creek is defined as the 89-km stretch of creek from the Broken River (at Caseys Weir) to the confluence with Boosey Creek near Katamatite. Upper Broken Creek flows across a flat, riverine plain and has naturally low runoff from its local catchment. It receives flood flows from the Broken River, although the frequency of these floods has been reduced by earthworks and road construction.

Upper Broken Creek has been regulated for more than a century. Before 2007, water was diverted into upper Broken Creek at Casey’s Weir to meet local demand, but recent water savings projects have reduced the demand on the creek. There is now low flow throughout the year between Caseys Weir and Waggarandall Weir. Flow below Waggarandall Weir is mainly influenced by rainfall and catchment runoff. These changes have reduced the amount of permanent aquatic habitat.

Delivery of water for the environment to the Broken River is primarily constrained by the availability of water. Usually, the available volume of water for the environment is insufficient to provide all recommended flows. Deliveries of water for the environment to upper Broken Creek are also restricted by channel capacity and by the need to avoid flooding lowlying adjacent land.

Traditional Owners
Storage manager
Environmental water holder

System map

Environmental watering objectives in the Upper Broken Creek

Fish icon
Increase native fish populations
Platypus icon
Maintain platypus populations
Plant icon
Maintain in-stream vegetation
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Support a wide range and high biomass of waterbugs, to break down dead organic matter and support the river’s food web
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Maintain water quality

Environmental values

The Broken River retains one of the best examples of healthy in-stream vegetation in a lowland river in the region. A range of native submerged and emergent plant species including eelgrass, common reed and water ribbons populate the bed and margins of the river. These plants provide habitat for a range of animals including small- and large-bodied native fish species. Murray cod, Macquarie perch, golden perch, silver perch, river blackfish, mountain galaxias and Murray- Darling rainbowfish all occur in the Broken River. The river also supports a large platypus population.

The upper Broken Creek area is dominated by unique box streamside vegetation and remnant plains grassy woodland. It supports numerous threatened species including brolga, Australasian bittern, buloke and rigid water milfoil. Much of the high-quality native vegetation in the region is set aside as a natural features reserve. Upper Broken Creek supports a variety of native fish species including carp gudgeon, Murray cod, golden perch and Murray-Darling rainbowfish, as well as platypus and common long-necked turtle.

Both the Broken River and upper Broken Creek are listed in the Directory of Important Wetlands in Australia.

Recent conditions

Below-average rainfall and above-average temperatures in the Broken River and upper Broken Creek in 2019–20 resulted in low inflows to the river and creek, low allocation of entitlements and low water availability for environmental flows.

In the Broken River, flow between Lake Nillahcootie and Casey’s Weir in reaches 1 and 2 was very different to that below Casey’s Weir in reach 3. The reaches between Lake Nillahcootie and Casey’s Weir have minimal tributary inflows and flow in these reaches is predominantly shaped by operational releases from Lake Nillahcootie for entitlement demands downstream. Reaches 1 and 2 had a stable, low-magnitude flow from July to November 2019 and then higher-magnitude flow and slightly more variability from December 2019 onwards. In comparison, the flow pattern in reach 3 is mainly shaped by unregulated tributary inflows. There were several natural freshes in this reach between July and October 2019, and stable, low-magnitude flow from November till April 2020. There were some natural freshes in the Broken River in autumn 2020.

Upper Broken Creek has no significant tributaries and its flow is primarily influenced by operational releases, catchment runoff and environmental flows. Upper Broken Creek had low flow from July to December 2019 and then slightly higher and more variable flow from January 2020 onwards. Water for the environment was predominantly used to meet targets for summer/autumn low flow, which had been generally met by operational flows in previous years. This meant flows from operational releases were lower in upper Broken Creek in 2019–20 than in previous years.

Traditional Owner cultural values and uses

Goulburn Broken CMA consulted with the Taungurung Land and Waters Council and Yorta Yorta Nation Aboriginal Corporation during the planning of environmental water deliveries in the Goulburn River. The Traditional Owners confirmed that the environmental and ecological objectives of the environmental watering align with their Land and Water Management Plans, and the CMA is continuing to work with both groups to identify how environmental water management can support cultural values.

Social, recreational and economic values and uses

In planning the potential watering actions in Table 1, Goulburn Broken CMA considered how environmental flows could support values and uses including:

  • water-based recreation (such as fishing)
  • riverside recreation and amenity (such as camping, birdwatching, picnicking and duck hunting)
  • community events
  • socio-economic benefits (such as supporting birds that control invasive species and providing green space and water in a dry landscape over summer).

Scope of environmental planning

Table 1 Potential environmental watering actions and objectives for the upper Broken Creek and Broken River

Potential environmental watering action1

Functional watering objective

Environmental objectives

Summer/autumn fresh (one fresh of 10-100 ML/day for 10 days during December to May as needed)

  • Maintain water quality, particularly oxygen levels, in refuge pools
Fish iconPlatypus iconPlant iconInsect iconDrop icon

Summer/autumn low flow (one to five ML/day during December to May)

  • Maintain pool and riffle habitat for native fish populations and waterbugs
  • Maintain access to habitat and food resources for platypus
  • Maintain habitat for in-stream vegetation
Fish iconPlatypus iconPlant iconInsect icon

Winter/spring low flow (five to 10 ML/day during June to November)

  • Maintain pool and riffle habitat for native fish populations and waterbugs
  • Maintain access to habitat and food resources for platypus
  • Maintain habitat for in-stream vegetation
Fish iconPlatypus iconPlant iconInsect icon
Broken River

Year-round low flow (five to 15 ML/day)

  • Maintain riffles, slackwater and pools to provide diverse hydraulic habitat for native fish, aquatic plants, platypus and waterbugs
  • Maintain habitat for in-stream and fringing vegetation, and prevent terrestrial vegetation colonising the stream bed
Fish iconPlatypus iconPlant iconInsect icon

Summer/autumn freshes (400–500 ML/day for two to eight days during December to May)

  • Scour sediments around large wood, and turn over bed sediments to replenish biofilms and increase productivity
  • Provide flow cues to stimulate native fish to breed and migrate
  • Provide flow to maintain in-stream and fringing aquatic vegetation
  • Maintain longitudinal connectivity for native fish passage
Fish iconPlant icon

1 Watering actions are listed in priority order and upper Broken Creek watering actions are higher priority than Broken River watering actions.

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
  • Commonwealth Environmental Water Office
  • Goulburn-Murray Water
  • Parks Victoria
  • Individual landholders who are on the Broken Environmental Water Advisory Group
  • Yorta Yorta Nation Aboriginal Corporation
  • Taungurung Land and Waters Council

Page last updated: 24/07/20