Water for the environment for the Latrobe, Thomson and Macalister systems is held in Blue Rock Reservoir, Thomson Reservoir and Lake Glenmaggie respectively.
The Thomson system receives a secure annual allocation which is available on 1 July each year, in addition to a share of the daily inflows to the Thomson Reservoir. In the Latrobe and Macalister systems, water availability depends on system inflows to Lake Glenmaggie and Blue
Rock Lake. Most of these inflows occur in winter and spring, so annual allocations are usually known before the start of summer.
In all three systems, the VEWH will carry over water from 2017–18 into 2018–19. In the Macalister system, the carryover will be used to deliver priority flows in July and August, and we will rely on further inflows to provide sufficient allocations to meet high-priority
watering demands later in 2018–19. In the Thomson and Latrobe systems, carryover water will be set aside to use in late winter and spring, by which time there should be morereliable estimates of seasonal allocations and the overall availability of water for the environment
in all three systems.
The probability of exceeding median rainfall in the Gippsland Region in early winter 2018 is better than average, but it has been particularly dry during summer and autumn 2018 and the catchments are very dry. The catchments will need significant rain to saturate the ground
before there is any marked effect on streamflow. There will be high reliance holdings of water for the environment to provide critical-flow components until natural run-off and unregulated flows increase.
Current holdings of water for the environment are likely to be sufficient to deliver the highest-priority watering actions in the Latrobe, Thomson and Macalister rivers in the first half of 2018–19. A return to drought conditions may significantly limit allocations of
water for the environment during 2018–19 and therefore deliveries of water for the environment later in the year will need to be managed to provide enough carryover to meet critical demands in 2019–20. Additional water for the environment may be sought via transfers
from within the Gippsland system or from another region, if allocations are inadequate to deliver important environmental outcomes.
Under an average-to-wet scenario, there will be sufficient water to meet all identified potential watering actions for the Macalister, Thomson and Latrobe systems. High inflows will also boost Water Holdings for 2019–20. Under a wet scenario, the Latrobe wetlands may be filled with natural flushing flows that have not occurred
on a large-scale since 2011–12.
Planning of water for the environment in the Snowy system is managed by the NSW Department of Industry, which consults the Victorian and Australian governments and stakeholder groups about water for the environment released to the Snowy River. The total volume for release and
daily release targets for the Snowy River from May 2018 to April 2019 are set in place and daily releases will not vary unless flows increase the risk of flooding downstream.