Picture: Lake Fyans

Review of January 2020 Operations

January was the third 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 25% of the historic average inflow for the same period (170,300 ML, excluding Taylors Lake inflow).

During January, the volume in storage decreased from 212,270 ML (37.9%) to 195,730 ML (35%).

Rainfall recorded at Grampians reservoirs ranged from 112% to 255% of average during January. The highest rainfall for the month was 77.4 mm recorded at Lake Wartook (169% of average), followed by Moora Moora Reservoir with 71.4 mm recorded for the month (156% of average). Lake Fyans recorded the lowest rainfall total with 37.0 mm, which equates to 119% of the monthly average. Despite above average rainfall totals, very dry catchments meant that the rainfall generally did not translate to flows in waterways or into reservoirs. The rain which fell directly on reservoirs added approximately 4 GL of water to the volume in storage.

Calculated net evaporation from reservoirs was approximately 6,050 ML for the month; with monthly evaporation still far exceeding rainfall (Net evaporation considers rainfall on the reservoir as an evaporation offset).

Environmental water releases during the month of January included those from Lake Wartook supplied to the MacKenzie River and Burnt Creek, Lake Lonsdale to the Mt William Creek and from 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 230 ML throughout the month of January, and Wimmera-Mallee Pipeline connected wetlands received less than 1 ML.

Consumptive entitlement holders collectively used 2,149 ML during January to supply urban and rural demands.


Planned February 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 autumn 2020. As such, these two climate drivers are expected to have little influence on the regional and Australian climate in the coming months.

It is anticipated that the focus of reservoir operations during February will continue to predominantly centre on routine delivery of water to entitlement holders, and operational actions to maximise headworks efficiency.

Many reservoirs are anticipated to remain at suitable levels through February for a range of recreational activities. Recreation users are reminded to take care and abide by signage at reservoirs. Please refer to the

Reservoir information page for further information on water levels and recreation activities permitted at each reservoir.

Blue-Green Algae blooms can be more common during warmer months. 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.


1 ML = 1 megalitre = 1 million litres