Picture: Lake Fyans


Review of April 2017 Operations

There was 190 ML of measurable inflow received into headworks storage during April. Year to date inflows (July – April) total 241,690 ML, which is 137% of the average for the same period (176,600 ML).

During April, the volume in headworks reservoirs declined by 6,590 ML, from 302,900 ML (54%) to 296,310 ML (53%).

Rainfall during April ranged from 101 mm at Lake Bellfield Reservoir to 56 mm at Lake Fyans. This has assisted in wetting catchments, but did not result in significant runoff.

A Blue-Green Algae warning remained in effect for Lake Toolondo. Regular monitoring is ongoing, with updates available from GWMWater’s website (www.gwmwater.org.au). (High levels of Blue-Green Algae, often referred to as a ‘bloom’, can make water unsuitable for both consumption and direct skin contact through recreational activities.)

Environmental releases continued from Lake Wartook, Rocklands Reservoir, Lake Lonsdale, and Taylors Lake during April. A total of 1,600 ML environmental flow was delivered from Lake Lonsdale to Mt William Creek, and 1,546 ML from Rocklands to the Glenelg River. The MacKenzie River downstream of Dad and Dave Weir received 369 ML of environmental water from Lake Wartook, and 346 ML was released from Taylors Lake to the Wimmera River.

Consumptive entitlement holders collectively used 923 ML during April to supply urban and rural system demands.

Net evaporation from reservoirs was approximately -2,600 ML for the month, with rainfall exceeding evaporation.

(Net evaporation considers rainfall on the reservoir as an evaporation offset.)

Planned May 2017 Operations

The Bureau of Meteorology is predicting drier than ‘average’ conditions over the coming three months. The Bureau’s El Niño–Southern Oscillation (ENSO) indicator remains at “El Niño watch” which indicates around a 50% chance of El Niño conditions developing during spring 2017. El Niño events have historically resulted in below average rainfall across south-eastern Australia.

Following significant rainfall in April, it is expected that further rainfall in May will begin to generate runoff into water storages.

Delivery of regulated environmental flow to MacKenzie River, Burnt Creek, Mt William Creek, Wimmera River, and Glenelg River is expected to continue through May. Regulated environmental flows may be ceased where natural (unregulated) flows are observed in waterways.

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 May. Regular monitoring for Blue-Green Algae at headworks reservoirs is ongoing through the autumn months.

Reservoirs are expected to remain at suitable levels through May 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.