Skip to content

The lower Broken Creek and Nine Mile Creek (referred to collectively as the lower Broken Creek) begins near Katamatite, downstream of where Boosey Creek enters Broken Creek, and then flows west to join the River Murray.

The lower Broken and Nine Mile creeks have been regulated for over 100 years, significantly altering their flow regimes. Pre-regulation, the creeks would have mainly flowed in winter and spring and the adjacent floodplain would have received more-regular flooding from overbank flows. In summer and autumn, the creeks would have had much less flow, often contracting to isolated pools or drying out completely. The creeks now have numerous weirs and flow at a relatively constant level from mid-August until mid-May to support adjacent irrigated farming. 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 River Murray when it dried. Both creeks now provide year-round habitat for native fish, and fish passage structures allow fish to move between weir pools. Environmental water is used to support these permanent fish habitats by providing flows to support fish passage and by providing higher flows to trigger fish movement, control water quality or flush azolla as necessary.

The lower Broken Creek is operated separately to the upper Broken Creek and Broken River because regulated water is delivered to the lower Broken Creek from the Goulburn and Murray systems via the irrigation channel network, rather than from the Broken River. 

Environmental water provided to the lower Broken Creek can be sourced from both the Goulburn and Murray systems. Environmental water is sourced from the Goulburn system through the East Goulburn Main Channel and from the Murray system through the Yarrawonga Main Channel. Water is then released into lower Broken Creek from irrigation area regulators along the length of lower Broken Creek. The priority river reach for environmental watering is reach 3 (from Nathalia Weir Pool to the River Murray). Environmental flows that target reach 3 are expected to also deliver the desired flows in reaches 1 and 2. The measurement point for target flows in the lower Broken Creek is at Rices Weir.

Environmental targets can also be met by water delivered from Lake Eildon (known as inter-valley transfers) or Hume Reservoir (known as choke bypass flows) to meet downstream consumptive demands in the River Murray. These consumptive deliveries occur usually during peak irrigation demand: from spring to autumn. These flows may help achieve the desired environmental objectives without the need to release environmental water.

Environmental watering objectives in the Lower Broken Creek

Fish icon
Protect and increase populations of native fish including the threatened Murray cod, golden perch and silver perch by maintaining habitat (water level and quality) and stimulating fish to migrate and spawn
Plant icon
Control excessive build-up of azolla, a native aquatic plant that can lower water quality in the creek when significant blooms occur
Water icon
Maintain healthy water oxygen levels

Environmental values

The 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. The associated floodplain and wetland habitats support box-dominated grassy woodland communities and numerous threatened species of state and national conservation significance including river swamp wallaby grass and the Australasian bittern.

Social, cultural and economic values

The lower Broken and Nine Mile creeks and associated floodplain and wetland habitats contain many important Aboriginal cultural heritage sites of significance for Traditional Owner groups including the Yorta Yorta Nation, provide water for agriculture and urban centres and support a variety of recreational activities (such as fishing and bushwalking).

Conditions mid-2017

The wet winter/spring in 2016 resulted in significant unregulated flows in the lower Broken Creek, which met or exceeded the environmental flow targets. The large flood event in the River Murray in September 2016 completely submerged Rices Weir, and high unregulated flows through the whole system successfully flushed all reaches of lower Broken Creek and significantly reduced the risk of azolla build-up in spring and summer. 

Environmental water was delivered to the lower Broken Creek from late October to maintain the target 250 ML/day flow rate. The flow release primarily aimed to freshen up the water quality around Rices Weir and reduce the effect of low-dissolved-oxygen water that backed up into the creek from the River Murray in October. The intervention provided a local refuge for native fish that were able to move into the creek via fishways and therefore escape the low oxygen levels in the River Murray. 

Flows at Rices Weir were maintained at 250 ML/day for most of summer and autumn to provide habitat for native fish and maintain water quality. The flow rate was reduced to 120 ML/day in April, once cooler conditions arrived and there was less risk of poor water quality. Planning is underway to maintain flows of 40 ML/day from mid-May to mid-August 2017 to allow native fish to move throughout the creek and between the creek and the River Murray during the irrigation shut-down period.

Scope of environmental watering

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

Potential environmental watering

Environmental objectives

Year-round low flows (40 ML/day)1

  • Provide native fish passage

Winter/spring low flows (120 ML/day in August–November)

  • Minimise azolla growth

Spring/summer/autumn low flows (150–300 ML/day in October–May)

  • Maintain water quality, including dissolved oxygen levels above 5 mg/L

Winter/spring freshes (120–250 ML/day for up to 14 days in August–November)

  • Remove large azolla blooms

Spring/summer low flows (250 ML/day in September–December)

  • Increase native fish habitat during migration and breeding seasons

1 Primarily during the irrigation season between mid-August and mid-May, but it may be delivered year-round subject to supply constraints.

Risk management

In preparing its seasonal watering proposal, Goulburn Broken CMA considered and assessed the risks of environmental watering and identified mitigation strategies. Program partners continually reassess risks and mitigation actions throughout the water year

Engagement

Waterway managers meet communities on environmental watering regionally, although other program partners also play a role.

In each region of Victoria, community engagement on environmental watering happens when environmental watering objectives and priorities are scoped (long term and annually), when delivering environmental water, and when reporting on environmental watering results.

In the Goulburn Broken region communities are involved in decisions about the Goulburn River and wetlands, Broken River and wetlands and the Murray River and wetlands. This happens through formal advisory groups: Environmental Water Advisory Groups focusing on rivers, a wetland advisory group and the Barmah Millewa Operations Advisory Group.

Who is engaged and how

Recreational users

Through formal advisory groups, recreational users provide local advice and raise opportunities for 'shared benefits' including whether the timing of environmental watering may align with key recreational events such as cod and duck opening. Recreational users are informed of environmental water deliveries and provide data that assists with reporting on the outcomes of environmental watering.

Goulburn-Murray Water directly engages with recreational user groups that use Goulburn-Murray Water water storages for recreation through planned consultations and meetings to discuss storage levels and potential impacts of environmental water releases from storages.

Environment groups

Through formal advisory groups, environment groups provide local knowledge, land management advice and advocate for the environment. They are also informed of environmental water deliveries and provide data that assists with reporting on the
outcomes of environmental watering.

Landholders/farmers

Through formal advisory groups, farmers and landholders (who often own land with river frontages) provide local knowledge and land management advice. They are also informed of environmental water deliveries and provide data that assists with reporting on the outcomes of environmental watering.

Traditional Owners

Through the Goulburn Broken Catchment Management Authority Indigenous Facilitator, the Yorta Yorta Nation (responsible for managing some land and reserves in the region) is given the opportunity to provide input to seasonal watering proposals through annual briefings with the Catchment Management Authority.

There are Yorta Yorta representatives from the Goulburn Broken region who are members of the Murray Lower Darling Rivers Indigenous Nations. The Victorian Environmental Water Holder, the Commonwealth Environmental Water Holder and the Murray Darling Basin Authority engage Murray Lower Darling Rivers Indigenous Nations on strategic (often longer term) issues related to environmental watering.

Councils

Through the wetland advisory group (due to their role as land managers for some wetlands), Councils provide local advice.
They also support local advertising during water delivery and share data for reporting.

Goulburn-Murray Water consults with the Greater Shepparton City Council and the Moira Shire Council regularly on water management, including on environmental water management.

General public

The Goulburn Broken Catchment Management Authority communicates through their website, media releases, advertisements in local papers, a column in Country News, in the Goulburn Broken Catchment Management Authority bi-monthly newsletter, social media, radio, community forums and partnered research.