Broken River and upper Broken Creek

The Broken River is a tributary of the Goulburn River, rising in the Wellington-Tolmie highlands and flowing northwest to Benalla and then west for a total distance of 190 km before it joins the Goulburn River near Shepparton (Figure 5.5.1). Lake Nillahcootie is the main storage on the Broken River. It is about 36 km upstream of Benalla and harvests water from the river to support stock and domestic supply and irrigated agriculture. The main tributaries of the Broken River are Hollands Creek, Ryans Creek, and Lima East Creek.

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 greater 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, although the total annual flow is considerably less than natural. 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 the 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 run-off from its local catchment. It receives flood flows from the Broken River, although the frequency of these floods has been reduced by river regulation, 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 Caseys Weir to meet local demand, but recent water savings projects have reduced the demand on the creek. There is now a low flow throughout the year between Caseys Weir and Waggarandall Weir. The flow below Waggarandall Weir is mainly influenced by rainfall and catchment run-off. 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 small volume of water holdings in the Broken system. Environmental water holders can trade water into the Broken system from other trading zones subject to relevant limits and conditions to meet environmental needs.

The bulk entitlement for the Broken system held by Goulburn-Murray Water stipulates that a minimum environmental flow – also known as passing flow – is to be maintained in the Broken River when there are natural flows into the system. The bulk entitlement also allows Goulburn-Murray Water and the Goulburn Broken CMA to agree to reduce the minimum passing flow and accumulate unused volumes for later releases that will provide a greater environmental benefit. In recent years, the passing flow has been reduced, accumulated and delivered to maintain a low flow (on days when there is no passing flow due to no natural flow into the system) and freshes in the Broken River. Accumulated passing flow is the first volume lost when the storage spills. Environmental flows in upper Broken Creek are restricted by the volume of available supply, channel capacity and the need to avoid flooding low-lying, adjacent land.

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 objectives in the Broken River and upper Broken Creek

Maintain native fish populations

Turn over bed sediments and scour around large wood to maintain in-channel habitat diversity

Maintain platypus populations

Maintain in-stream vegetation

Maintain a wide range and high biomass of waterbugs to break down dead organic matter and support the river’s food web

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. Murray cod, Macquarie perch, golden perch, silver perch, river blackfish, mountain galaxias, southern pygmy perch and Murray-Darling rainbowfish all occur in the Broken River. The river also supports a large platypus population.

Upper Broken Creek is dominated by unique box streamside vegetation and remnant plains grassy woodland. The creek and its streamside zone support numerous threatened species, including brolga, Australasian bittern, buloke and ridged watermilfoil. 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.

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

Traditional Owner cultural values and uses

The Broken River system flows through Taungurung and Yorta Yorta Country. The Broken Creek is on Yorta Yorta Country. The Taungurung Land and Waters Council and the Yorta Yorta Nation Aboriginal Corporation are members of the Broken Environmental Water Advisory Group. Water for the environment in the Broken system supports the health of cultural values and landscapes, including intangible cultural heritage, valued species and traditional food and medicine plants.

Each year, the Goulburn Broken CMA meets with the Taungurung Land and Waters Council and the Yorta Yorta Nation Aboriginal Corporation to discuss plans for environmental watering in the Broken River and upper Broken Creek. Meetings were held in early 2023 to discuss 2023-24 environmental watering priorities. Both groups support the proposed watering actions.

The Taungurung Land and Waters Council plans to assess cultural values and objectives for the Broken River through healthy Country assessments like Aboriginal Waterway Assessments. These will help the council develop more-specific cultural objectives for the Broken River system in future as well as culturally informed recommendations for water for the environment.

In 2021, the Yorta Yorta Nation Aboriginal Corporation provided the following statement about the cultural values of the Broken River system, including Broken Creek:

“The Broken River (and Broken Creek) holds 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 river also has significant stands of old-growth river red gum containing important habitat and exhibiting scars made from carving out canoes and coolamons.”

Social, recreational and economic values and uses

In planning the potential environmental watering actions in Table 5.5.1, the Goulburn Broken CMA considered how environmental flows could support values and uses, including:

water-based recreation (such as canoeing, fishing, kayaking and swimming)
riverside recreation (such as birdwatching, bushwalking, camping, duck hunting and picnicking)
green and blue spaces important to the community for wellbeing and mental health due to the otherwise dry environment
community events and tourism (such as markets around Benalla Lake)
socioeconomic benefits (such as maintaining the volume of water in the lower sections to optimise the efficiency of deliveries of consumptive water, maintain water quality for irrigation, stock and domestic use and support terrestrial birds that help control agricultural pests).

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 5.5.1 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 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 5.5.1 Potential environmental watering actions, expected watering effects and associated environmental objectives for the Broken River and upper Broken Creek

Potential environmental watering action	Expected watering effects	Environmental objectives
Upper Broken Creek¹
Winter low flow (5-10 ML/ day during June to August)	Maintain aquatic habitat and connections between weir pools for native fish and platypus Inundate benthic surfaces and large wood located at the bottom of the channel, which serves as habitat for waterbugs Maintain water quality and oxygen levels for native fish, platypus and waterbugs
Spring low flow (5-10 ML/ day during September to November)
Summer low flow (5-10 ML/day during December to February)
Autumn low flow (5- 10 ML/day during March to May)
Summer/autumn fresh (one fresh of 50-100 ML/ day for 10 days during December to May)	Flush pools to improve their water quality and increase oxygen levels
Broken River (reaches 1, 2 and 3)²
Winter low flow (15-100 ML/day during June to August)	Maintain habitat for in-stream and fringing vegetation, and prevent terrestrial vegetation from colonising the stream bed Maintain riffles, pools and slackwater to provide diverse hydraulic habitat for native fish, aquatic plants, platypus and waterbugs Maintain water quality and oxygen levels for native fish, platypus and waterbugs
Spring low flow (15- 100 ML/day during September to November)
Summer low flow (15- 100 ML/day during December to May)
Autumn low flow (15-100 ML/day during March to May)
Summer/autumn fresh (one fresh of 400-500 ML/day for two to five days during December to May)	Scour sediments around large wood, turn over bed sediments, replenish biofilms and maintain macrophyte habitat Provide flow cues to stimulate native fish to breed and migrate Maintain longitudinal connectivity for native fish passage

¹ Potential watering actions in upper Broken Creek will be delivered at a lower magnitude if insufficient water is available to achieve the target magnitude.

²30-100 ML/day is the recommended flow required to ensure optimal habitat and water quality is achieved in the Broken River. When water availability is low, a flow may need to be delivered at 15 ML per day to provide the minimum

Page last updated: 01/07/22