The western region experienced near-average rainfall through winter 2018, but because the catchment was still very dry from the previous year the catchment run off was low, and most major storages received very modest inflows. The main gains in winter 2018 were flows into Rocklands Reservoir and through the Glenelg tributaries. From early spring 2018 to the end of autumn 2019, rainfall was below average and temperatures were above-average, resulting in system inflows for the entire 2018–19 year that were just 20 percent of the historic average of inflows. For the first time on record, there was no measurable flow in the upper Wimmera River at Huddlestons Weir for the entire year.
Dry and hot conditions over the two previous years caused storage levels to decline to below 40 percent of total storage capacity in early April 2019, and the allocations to the VEWH’s entitlement reached a maximum of 55 percent in April 2019. The CEWH did not receive any allocation in 2018–19, but it retained some carryover from previous years which was used.
Waterway managers and the VEWH were cautious with the use of water for the environment in 2018–19, to assure supply for the upcoming 2019–20 year. Some good natural flow in the Glenelg catchment reduced the need for supply of the Glenelg River in winter and spring. In both the Wimmera and Glenelg systems, passing flows were reduced at times and accrued for use late in the year.
Below-average rainfall and above-average temperatures are predicted to continue for the western region through winter 2019. If dry conditions persist, the highest priority for the use of water for the environment will be to protect water quality, maintain connectivity between deep pool habitats and continue to improve the resilience of in-stream native plants and animals. Carryover available going into 2019–20 will be particularly important going into all climatic scenarios this year, as allocation to the environmental entitlements in the western region are not expected to be made in July 2019. It is also unlikely that under drier climatic conditions, without significant inflows to storages during winter and spring, both the wetland entitlement and CEWH’s entitlement are expected to receive no allocations in 2019–20.
If conditions become wetter and environmental allocations increase, priority will be given to reserving water for use in 2020–21 and delivering some larger flows to maintain or improve conditions in the waterways and wetlands. 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.