Review of November 2018 Operations
No measurable inflow was received to reservoirs during November, with total inflows of 37,910 ML received for the 2018-19 year to date (or 35,330 ML excluding Taylors Lake). This is equivalent to 22% of the historic average inflow for the same period (161,600 ML excluding Taylors Lake inflow).
During November, the volume in headworks reservoirs decreased from 279,580 ML (50%) to 265,410 ML (47.4%).
Rainfall during November was close to average for Lake Bellfield, Lake Wartook and Taylors Lake, however this fell to around 60-70% of average at most other Grampians reservoirs. The highest rainfall for the month was 57.0 mm, recorded at Lake Bellfield, followed by 53.6 mm received at Lake Wartook. Toolondo Reservoir received the least rainfall for the month with 24.8 mm recorded. With warmer temperatures observed during November, net evaporation from reservoirs was 3,670 ML for the month; with evaporation exceeding rainfall, (Net evaporation considers rainfall on the reservoir as an evaporation offset).
Environmental water releases continued in both the Wimmera and Glenelg catchments, with a total of 141 ML delivered to the Wimmera River from Taylors Lake, 1,133 ML supplied to the lower Mt William Creek from Lake Lonsdale, and 509 ML supplied to the lower MacKenzie River and Burnt Creek from Lake Wartook. A total of 1,290 ML was released from Rocklands Reservoir to the Glenelg River, and 56 ML was supplied from Moora Moora Reservoir as part of an environmental watering trial for the upper Glenelg River.
Wimmera-Mallee Pipeline supplied recreation lakes received 170 ML throughout the month of November, with top-up supplies made to number of lakes. 13 ML was supplied to Wimmera-Mallee Pipeline connected wetlands within the Mallee, North Central and Wimmera Catchment Management Authority areas.
Consumptive entitlement holders collectively used 1,300 ML during November to supply urban and rural demands.
Planned November 2018 Operations
The Bureau of Meteorology in their most recent climate outlook have predicted around a 50% chance of above average rainfall during December. BoM reports that the El Niño Southern Oscillation (ENSO) outlook remains at ‘El Niño ALERT’ status. This indicates a 70% chance of El Niño conditions developing in the coming months, which is triple the normal likelihood for a given year. During El Niño events, rainfall in eastern Australia has historically been below average during spring, with warmer daytime temperatures also occurring. In addition to this, the Indian Ocean Dipole (IOD) has remained at positive IOD levels, however this typically has less influence on Australian climate from December to April.
The Storage Manager will continue to monitor BoM climate outlooks and consider this information in its planning activities
The Storage Manager’s operational focus for December will centre on the supply of entitlement holder requirements. Water releases for the environment are anticipated to continue throughout the month in both Wimmera catchment waterways and to the Glenelg River.
Reservoirs are generally anticipated to remain at suitable levels through December for a range of recreational activities, including boating at reservoirs where this is permitted. As some reservoirs may approach lower levels over the summer months, 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 the warmer summer 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.