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Traditional Owner cultural values and uses
Melbourne Water has made initial contact with Wathaurung Aboriginal Corporation (Wadawurrung) and Wurundjeri Woi-Wurrung Cultural Heritage Aboriginal Corporation, to discuss environmental watering in the Werribee system.
Social, recreational and economic values and uses
In planning the potential watering actions in Table 3.5.1, Melbourne Water considered how environmental flows could support values and uses including:
• water-based recreation (such as fishing)
• riverside recreation and amenity (such as improved water quality for communities)
• tourism (such as Werribee Zoo).
Recent conditions
Total rainfall in the Werribee system during 2019–20 was close to the long-term annual average, but rainfall was not evenly distributed across all reaches or storages. Pykes Creek Reservoir and Melton Reservoir both spilled in winter and spring 2019, which delivered large flows to the lower Werribee River. Inflows to Lake Merrimu remained low throughout the year, and environmental flows provided some flow in Pyrites Creek in spring 2019. By early March 2020, holders of high-reliability water shares in the Werribee system had received 100 percent allocations, and holders of low-reliability water shares had received 60 percent allocations. Small volumes of inflows into Lake Merrimu were attributed to the environmental entitlement throughout 2019–20.
Most of the potential watering actions for the lower Werribee River were delivered in 2019–20. Natural events provided regular freshes throughout the year, and water
for the environment was used to deliver additional summer freshes and some low flows in June 2020. One of the summer freshes was used to flush an algal bloom that developed in the lower Werribee River during early summer. Low flows during autumn and winter were achieved by passing flows delivered by the storage manager.
In Pyrites Creek, water for the environment was used to deliver low flows and two spring freshes. These flows connected habitat pools for frogs, waterbugs and native fish, flushed sediment from pools and supported the recruitment and growth of native vegetation in the stream and along the margins of the banks. About one-third of flow in Pyrites Creek seeps into groundwater reserves or evaporates, but all flow that reached Melton Reservoir was re-harvested for later use.
Scope of environmental watering
Table 3.5.1 describes the potential environmental watering actions in 2020–21, their functional watering objectives (that is, the intended physical or biological effect 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 functions.
3.5 Werribee system
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