Review of March 2020 Operations
March was the fifth consecutive month in the 2019/20 water year with no measurable inflow recorded to any reservoir from catchments. Year to date inflows for the 2019/20 season remain at 50,760 ML (42,740 ML, excluding Taylors Lake), which is equivalent to 24% of the historic average inflow for the same period (174,200 ML, excluding Taylors Lake inflow).
During March, the total volume in storage decreased by 13,870 ML, from 195,730 ML (35%) to 181,860 ML (32.5%).
Rainfall recorded at Grampians reservoirs ranged from 40% to 67% of average during March. The highest rainfall for the month was 18.4 mm recorded at Lake Bellfield (48% of average), followed by Rocklands Reservoir with 16.6 mm recorded for the month (56% of average). Taylors Lake recorded the lowest rainfall total with 11.2 mm, which equates to 50% of the monthly average.
Calculated net evaporation from reservoirs was approximately 5,000 ML for the month; with monthly evaporation exceeding rainfall (Net evaporation considers rainfall on the reservoir as an evaporation offset).
A planned transfer of approximately 2,500 ML from Lake Bellfield to Lake Fyans commenced in late March. This transfer will support water levels and water quality in Lake Fyans.
Environmental water releases during the month of March included those from Lake Wartook to the MacKenzie River and Burnt Creek, Lake Fyans to the Mt William Creek upstream of Lake Lonsdale, and Taylors Lake to the Wimmera River. Release of water for the environmental also continued from Rocklands Reservoir to the Glenelg River.
Wimmera-Mallee Pipeline supplied recreation lakes received 149 ML throughout the month of March, and Wimmera-Mallee Pipeline connected wetlands received less than 1 ML.
Consumptive entitlement holders collectively used 1,322 ML during March to supply urban and rural demands.
Planned April 2020 Operations
The Bureau of Meteorology (BOM) in their most recent El Niño -Southern Oscillation (ENSO) outlook have stated that both the Indian Ocean Dipole (IOD) and the El Niño–Southern Oscillation (ENSO) are likely to remain neutral into winter 2020. As such, these two climate drivers are expected to have little influence on the regional and Australian climate in the coming months.
The transfer from Lake Bellfield to Lake Fyans which commenced in late March is scheduled to conclude on 6 April. Beyond this transfer, it is anticipated that the focus of reservoir operations during April will continue to predominantly centre on routine delivery of water to entitlement holders, and operational actions to maximise headworks efficiency.
Although many reservoirs are anticipated to remain at suitable levels through April for a range of recreational activities, boat ramps and camping grounds have been temporarily closed to comply with the with the Victorian Government ‘Stay at Home’ period. Please refer to the Reservoir information page for further information on current restrictions and recreation activities permitted at each reservoir.
While Blue-Green Algae blooms are generally less common during the cooler months, it is still possible for these to occur. Recent Blue-Green Algae warnings for reservoirs can be found on the Storage Manager News Feed and all current warnings are available from the GWMWater Algae Warnings webpage.
Note: 1 ML = 1 megalitre = 1 million litres