Review of February 2024 Operations
Well below average rainfall totals were recorded at all storages during February, with less than 1 mm recorded at all locations. The highest monthly rainfall total received was recorded at Lake Fyans (0.6 mm, or 2% of historic monthly average) and Moora Moora Reservoir (0.6 mm, or 2% of historic monthly average), with a number of storages failing to record any rainfall for the month.
With warm conditions prevailing and little to no rainfall across headworks storages, there was no inflow to storages recorded for the month. Year to date inflow remains at 52,550 ML or 30.5% of historical average to February.
Between 7 February and 6 March 2024, the total volume in storage decreased from 367,400 ML (65.6%) to 344,540 ML (61.5%), representing a decrease of 22,860 ML (4.1%).
The total monthly calculated net evaporation from all reservoirs was higher than expected in February, with warm dry conditions increasing evaporation from headworks storages. Approximately 15,190 ML of net evaporated was calculated for headworks storages during the month of February, with evaporation from reservoirs far exceeding rainfall. (Net evaporation considers rainfall on the reservoir as an evaporation offset).
Environmental demand from the headworks system remained consistent throughout February. A total of 2,074 ML of passing flows were released from Rocklands Reservoir to the Glenelg River and 1,118 ML of passing flows released from Lake Lonsdale to the Mt William Creek. In addition, a total of 855 ML of regulated releases were delivered to the MacKenzie River and Burnt Creek systems from Lake Wartook and 37 ML of regulated releases delivered to the Glenelg River from Rocklands Reservoir.
A total of 0.4 ML was supplied to wetlands from the Wimmera-Mallee Pipeline during the month, and 249 ML was delivered to Wimmera-Mallee Pipeline connected recreation lakes.
Consumptive entitlement holders collectively used approximately 1,720 ML during February to supply their respective urban and rural demands.
March 2024 Operations and Climate Outlook
The Bureau of Meteorology (BoM) have observed that although atmospheric indicators are mixed, they remain consistent with a steadily weakening El Niño, with models indicating conditions will reach a neutral state sometime in Autumn 2024.
The BOM also note that based on the historical records, around 50% of El Niño events have been followed by an ENSO-neutral year, and 40 to 50% have been followed by La Niña. However, global oceans have warmed significantly over the past 50 years.
The Indian Ocean Dipole (IOD) has returned to neutral conditions and any event is unlikely to form until after April due to the monsoon trough shifting south, changing wind patterns, and preventing a IOD pattern from forming.
Rainfall outlooks indicate a less than average chance (35-40%) of rainfall exceeding the median during March. Daytime temperatures are expected to remain elevated, with the BOM projecting a >65% chance of exceeding median max temperatures for the remainder of March. Given the expected dry conditions, the operational focus for March will continue to be supplying entitlement holders.
Reservoirs are projected to hold suitable levels during March for a range of recreational activities. Recreation users are reminded to take care and abide by signage at reservoirs. Please refer to GWMWater’s Reservoir information page for further information on water levels and recreation activities permitted at each reservoir.
There is currently a Blue-Green Algae warning issues for Lake Toolondo. Information on all current algae warnings as well as general information on Blue-Green Algae is available from the GWMWater Algae Warnings webpage.