Page 198 - VEWH Seasonal Watering Plan 2020-21
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 5.2 Victorian Murray system
The Victorian Murray system contains many significant floodplains and wetland systems covering the Goulburn Broken, North Central and Mallee CMA areas. The Barmah Forest, Kerang wetlands and Hattah Lakes are internationally recognised Ramsar-listed sites due to the significance of their wetland types and the abundance and range of waterbird species that use them. Many other wetlands in the system are either nationally or regionally significant.
Water for the environment can be supplied
to the Victorian Murray system from a range
of sources. These include entitlements held
by the VEWH, which includes those held on behalf of the Living Murray program and the Commonwealth Environmental Water Holder; reuse of return flows; and in some instances, use of operational water en route. The source
of the water used for individual watering actions and the ability to deliver all watering actions will depend on water availability, water commitments by other environmental water holders and operational requirements. As a result, the following Victorian Murray system sections do not specify the expected availability of water for the environment.
5.2.1 Barmah Forest
System overview
The Barmah-Millewa Forest covers 66,000
ha and spans the New South Wales (NSW)– Victoria border between Tocumwal, Deniliquin and Echuca (Figure 5.2.1). It is listed under
the (Ramsar) Convention on Wetlands
of International Importance (the Ramsar Convention), the Australian Directory of Important Wetlands and is one of six Living Murray icon sites. The forest’s Victorian components are
the Barmah National Park and part of the River Murray Reserve, covering 28,500 ha of forest and wetlands that support a vast range of significant plant and animal species.
The wetlands throughout the forest continue to provide a constant source of nutritional foods and significant fibres for the Yorta Yorta People. It is also evident that the resources in the landscape were utilized to manufacture canoes, shields and carrying devices.
Flooding in the Barmah-Millewa Forest depends on flows in the Murray River. A natural narrowing of the river (known as the Barmah choke) restricts flow and causes overbank flooding when flows below Yarrawonga Weir exceed
the channel’s capacity. This restriction influences both
the operation of Yarrawonga Weir and the upper limit of environmental flows that can be delivered to the forests.
Prior to river regulation for water supply, flooding would have regularly occurred with high flows from rainfall in winter and spring – helping to shape a rich and productive forest environment. Today, flooding in the forest is also influenced by system operation for water supply for users downstream in the Murray River, which can cause damage to the forest and banks of the river depending on the timing and volume of the flows.
The delivery of irrigation water during summer/autumn is managed to minimise unseasonal flooding of the forest. Regulators along the banks of the Murray River that control flow between the river and the forest remain closed during summer and autumn to restrict flow through low-lying flood runners. The delivery of water to Barmah Forest is also limited by a flow constraint below Yarrawonga Weir
to minimise impacts to adjacent farming operations in
NSW. The current constraint limits releases to a maximum of 18,000 ML per day between July and September (with potentially-affected landholder support) and to 15,000 ML per day for the rest of the year. To overcome this constraint, most environmental flows are shared between Barmah
and Millewa forests to deliver water to low-lying wetlands
in each forest at least every second year. It is currently not possible to achieve the desired flood depth and duration for floodplain marsh vegetation in both forests at the same time without larger natural flooding.
Water management at Barmah–Millewa Forest seeks
to build on natural flow and the delivery of consumptive and operational water en route to optimise environmental outcomes when possible. As Barmah-Millewa Forest
is located towards the upper reaches of the regulated portion of the Murray River, water for the environment that passes through the forest can often be used at sites further downstream as part of multi-site watering events.
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