Review of July 2018 Operations
The end of July marks the first month of the 2018/19 water year. A total of 6,710 ML inflow was received into reservoirs during July, equivalent to 20% of the historic average July inflow (34,300 ML excluding Taylors Lake). These low inflows have resulted from below average rainfall during July and dry catchment conditions prior to winter.
During July, the volume in headworks reservoirs increased from 257,750 ML (46.1%) to 267,340 (47.8%).
Rainfall was below average at all reservoirs during July. The highest rainfall for the month was 134.4 mm, recorded at Lake Bellfield followed by 109 mm received at Lake Wartook. Taylors Lake received the least rainfall for the month with 35.8 mm.
Environmental water releases are generally lower during the winter period due to cool weather and natural flows in waterways. 875 ML of passing flows were released from Rocklands Reservoir to the Glenelg River, supplemented by 550 ML of regulated environmental water. No water was released for the environment in the Wimmera catchment during July
Wimmera-Mallee Pipeline supplied Recreation Lakes received 93 ML throughout the month of July, with top-up supplies commencing for a number of lakes.
Consumptive entitlement holders collectively used 857 ML during July to supply urban and rural demands.
Although rainfall for the month was below average, net evaporation from reservoirs was (negative) 3,980 ML for the month; with rainfall exceeding evaporation, (Net evaporation considers rainfall on the reservoir as an evaporation offset).
Planned August 2018 Operations
The Bureau of Meteorology (BoM) in their most recent climate outlook have predicted a 20% to 30% chance of above average rainfall over August. BoM reports that the El Niño Southern Oscillation (ENSO) has been upgraded to an ‘El Niño WATCH’. This indicates a 50% chance of El Niño conditions developing later in 2018, which is twice 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. 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 August will continue to be on water harvesting activities. The supply of passing flow obligations is anticipated to continue during the month, and other environmental watering activities may commence should catchment conditions remain dry.
The Storage Manager will continue to monitor conditions and update its transfer planning over the coming weeks, in consultation with entitlement holders. If catchment conditions begin to deteriorate, any required transfers may be brought forward to commence in late August in order to minimise operating losses.
Further information in relation to water transfers are described in the Storage Manager’s Annual Operating Plan.
Reservoirs are expected to remain at suitable levels through August for a range of recreational activities, including boating at reservoirs where this is permitted. Please refer to the Reservoir information page for further information on water levels and recreation activities permitted at each reservoir.
While Blue-Green Algae (BGA) blooms are generally less common during the cooler months, there is still ability 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.