Review of June 2017 Operations
There was 450 ML of measurable inflow received into headworks storages during June, which is 3% of the June historic average (17,200 ML). Inflows for the 2016-17 water year (July 2016 – June 2017) totalled 244,660 ML, which is 122% of the historic annual average (199,800 ML).
During June, the volume in headworks reservoirs decreased by 2,110 ML, from 298,160 ML (53.3%) to 296,050 ML (52.9%).
Rainfall was well below average for June, with totals ranging from 13 mm at Lake Wartook Reservoir to 5 mm at Lake Lonsdale.
The Blue-Green Algae warning was lifted for Toolondo Reservoir, with sampling confirming that concentration of blue-green algae remains below the warning level.
Environmental releases continued during June, with a total of 241 ML environmental water delivered from Lake Wartook to MacKenzie River.
Consumptive entitlement holders collectively used 761 ML during June to supply urban and rural system demands.
Net evaporation from reservoirs was approximately 600 ML for the month, with evaporation exceeding rainfall. (Net evaporation considers rainfall on the reservoir as an evaporation offset.)
Planned July 2017 Operations
The Bureau of Meteorology continues to predict drier than ‘average’ conditions over the coming three months. The Bureau’s El Niño–Southern Oscillation (ENSO) indicator is currently ‘inactive’, with neither El Niño nor La Niña expected to influence Australia’s climate this year. The Indian Ocean Dipole (IOD) is also neutral, however some climate models suggest a positive IOD event could develop over the coming months. Positive IOD events are often associated with below average winter and spring rainfall for southern parts of Australia.
Following above average rainfall in April and May, the Grampians reservoirs have experienced a relatively dry June with total inflow to reservoirs being less than evaporation. Headworks operations for the month will be focussed on water harvesting activities
In the event of strong inflows to Lake Wartook, transfers to Taylors Lake may be required during July to manage Lake Wartook to its target-filling curve. The reservoir was tracking below its target-filling curve at the start of July. Releases to manage the rate of filling are part of the normal operating procedure for Lake Wartook.
Delivery of regulated environmental flow to the lower MacKenzie River will continue through July. Passing flow obligations will be delivered from Lake Lonsdale and Rocklands Reservoir, consistent with storage management and entitlement rules. Passing flows are dependent on inflows occurring to the respective reservoirs.
The routine delivery of water to consumptive entitlement holders will be ongoing.
The Storage Manager will continue its regular monitoring of reservoir levels, weather forecasts and waterways during July. Monitoring for Blue-Green Algae at headworks reservoirs is ongoing through the winter months at a reduced frequency.
Reservoirs are expected to remain at suitable levels through July for a range of recreational activities, including boating at reservoirs where this is permitted. Please refer to the
Reservoir Level information page for further information on water levels and recreation activities permitted at each reservoir.