Review of January 2019 Operations
January received some of the lowest rainfall totals on record, with no measurable inflow observed for a third consecutive month. Total inflows remain at 38,120 ML for the 2018-19 year to date (or 35,540 ML excluding Taylors Lake). This is equivalent to 21% of the historic average inflow for the same period (170,300 ML excluding Taylors Lake inflow).
During January, the volume in headworks reservoirs decreased from 256,940 ML (45.9%) to 230,610 ML (41.2%).
Rainfall during January was well below average for all storages. The highest rainfall for the month was 4.4 mm, recorded at Lake Bellfield (9% of average) followed by 2 mm received at Lake Wartook (4% of average). Toolondo Reservoir and Taylors Lake received no rainfall for the month. In addition to the dry conditions, daytime temperatures during January were well above average. Net evaporation from reservoirs was 9,500 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 1,382 ML delivered to the Wimmera River from Taylors Lake, 72 ML supplied to the lower Mt William Creek from Lake Lonsdale, and 662 ML supplied to the lower Mackenzie River and Burnt Creek from Lake Wartook. A total of 1,755 ML was released from Rocklands Reservoir to the Glenelg River.
Wimmera-Mallee Pipeline supplied recreation lakes received 143 ML throughout the month of January, with top-up supplies made to number of lakes. No water was supplied to Wimmera-Mallee Pipeline connected wetlands within the Mallee, North Central and Wimmera Catchment Management Authority areas.
Consumptive entitlement holders collectively used 2,346 ML during January to supply urban and rural demands.
Planned February 2019 Operations
The Bureau of Meteorology (BoM) in their most recent climate outlook have stated that the El Nino-Southern Oscillation (ENSO) remains neutral and have revised the ENSO outlook to El Nino WATCH. This indicates a 50% chance of El Niño conditions developing during autumn or winter 2019. Several of the Bureau’s models are currently indicating a possibility of an El Nino event occurring in 2019. During El Niño events, rainfall in south eastern Australia has historically been below average during winter and spring, with warmer daytime temperatures also occurring.
The Indian Ocean Dipole (IOD) remains neutral. The Indian Ocean Dipole generally has little influence on Australian climate between December and 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 February will again 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 February for a range of recreational activities. 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.