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System overview
The Tarago River rises in the Tarago State
Forest and flows into the Tarago Reservoir at Neerim. The reservoir harvests inflows from all upstream tributaries to supply towns on the Mornington Peninsula and around the Western Port area, and it is also used to manage flows for downstream irrigators. Below the reservoir, the river flows close to the town of Rokeby before meeting the Bunyip River at Longwarry North. From there, the Bunyip River flows through a modified, straightened channel — Bunyip Main Drain — that discharges into Western Port. The Bunyip Main Drain supplies many irrigators in the catchment.
Water available under the Tarago environmental entitlement is stored in and released from Tarago Reservoir. This water is primarily used to meet environmental objectives in reach 2, which is between the reservoir and the confluence of the Tarago and Bunyip rivers, as Figure 3.3.1 shows. Water for the environment that is delivered to reach 2 also supports environmental flow recommendations in reach 6 (Bunyip Main Drain).
Year-round passing flows in the Bunyip and Tarago rivers are stipulated under both the environmental entitlement and Melbourne Water’s bulk entitlement. These passing flows are generally sufficient to meet the minimum low- flow requirements in summer/autumn, but are much less than the recommended minimum flows in winter/ spring; and do not provide any of the freshes or higher flows that are needed throughout the year to support environmental outcomes.
Water releases to meet irrigation demands create variable flow patterns in the Tarago and Bunyip rivers throughout the year. The magnitude and timing of these releases can influence environmental outcomes, and Melbourne Water continues to work with Southern Rural Water to optimise the shared value derived from irrigation releases.
Environmental values
The Tarago system contains several significant and threatened native plant and animal species including Australian grayling, long pink-bells, tree geebung and swamp bush-pea. The upper catchment (reach 2) has healthy streamside vegetation and diverse in-stream habitat that supports platypus and native fish including river blackfish and mountain galaxias. The lower catchment (reach 6) has been highly modified, but it still contains patches of remnant vegetation and healthy populations of Australian grayling and platypus.
Environmental watering objectives in the Tarago River
Traditional Owner cultural values and uses
Melbourne Water has made initial contact with Boon Wurrung Foundation, Bunurong Land Council Aboriginal Corporation and Wurundjeri Woi Wurrung Cultural Heritage Aboriginal Corporation, to discuss environmental watering in the Tarago/Bunyip system.
Social, recreational and economic values and uses
If the timing or management of planned environmental flows may be modified to align with a community benefit, this is acknowledged in Table 3.3.1 with an icon.
Melbourne Water may time a summer fresh in the Tarago River to occur on the long weekends in January or March 2020, so visitors and long-term residents of the Glen Crombie Caravan Park alongside the river can enjoy the additional flows in the river.
3.3 Tarago system
    Increase populations of native fish including threatened species (such as the Australian grayling)
    Maintain channel form and structure
   Increase platypus populations
    Increase native streamside and aquatic plant communities on the riverbank and in the channel
    Increase the diversity and biomass of waterbugs, to support aquatic foodwebs
  Watering planned to support peaks in visitation (e.g. camping or other public activities on long weekends or school holidays)
Victorian Environmental Water Holder | Seasonal Watering Plan 2020–21 | 97

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