Rainfall across the western region in 2019–20 was below the long-term average for the third consecutive year. Despite the overall dry conditions, there were some periods of higher rainfall that contributed flow to the Wimmera and Glenelg rivers. Winter rain caused the Wimmera River above Huddlestons Weir to flow for the first time in more than a year, which met the planned watering actions in the Wimmera and Glenelg systems for the first few months of 2019–20. Water for the environment was needed to supplement flows in the Wimmera and Glenelg systems from October 2019 onwards. Continuous flow was maintained in the Glenelg River between Rocklands Reservoir and to the top of the estuary at Dartmoor throughout 2019–20 and periodic flow in the Wimmera River to Dimboola. However, environmental watering in some parts of the MacKenzie River, Burnt Creek and Mount William Creek was lower than planned, due to release limits at selected storages.
Water storages across the Wimmera-Mallee headworks were collectively below 30 percent of capacity at the end of April 2020. The VEWH received 42 percent allocation against its environmental entitlement in 2019–20. The CEWH did not receive any allocation in 2019–20, but all remaining carryover held from previous years’ allocations was delivered in the Wimmera River and Mount William Creek during summer 2019–20.
Above-average rainfall and above-average temperatures are predicted for the western region in winter 2020, but the Wimmera-Mallee headworks storages will need significant inflows before any allocations are made to the environmental entitlement. The storage manager has indicated that entitlement holders will only receive low volumes of allocations in 2020–21 under drought, dry and average scenarios, and they are unlikely to receive full allocations even under a wet scenario.
If environmental allocations do not significantly increase in winter/spring 2020, environmental water for the rest of 2020–21 will be managed in line with drought or dry scenarios in both the Wimmera and Glenelg systems. The focus will be on delivering minimum low flow and small freshes as needed to maintain continuous river flow where possible, to maintain refuge pools where continuous flow cannot be achieved and to protect water quality. Carryover from 2019–20 will be critical in supporting these watering actions. If system inflows deliver higher environmental allocations, environmental water may be used to deliver winter/spring freshes and low flow in the Glenelg River through to reach 2, deliver additional winter/spring freshes in the Wimmera River and extend the summer/autumn low flow and freshes through to reach 3 of the MacKenzie River. Winter/spring inflows to the Wimmera-Mallee headworks storages will need to be well above average, to allow wet-scenario watering actions to be delivered in 2020–21.
The Wimmera-Mallee wetlands entitlement is not likely to receive any allocation in 2020–21 under drought, dry or average scenarios, so managed environmental deliveries to those sites will rely on carryover from 2019–20. The continuing focus of environmental watering in the Wimmera-Mallee wetlands will be to provide refuge and maintain habitat in the dry landscape, to support local plants and animals.
