Lower Broken Creek

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.

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.

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