Picture: Lake Fyans

Review of August 2017 Operations

There was around 38,900 Megalitre (ML) of measurable inflow received into headworks storages during August, which is around 48% of the August historic average (80,600 ML).

During August, the volume in headworks reservoirs increased by 40,300 ML from 306,790 ML (54.8%) to 347,090 ML (62.0%).

Rainfall was above average at some reservoirs for the month of August, with totals ranging from 185mm at Lake Bellfield to 72 mm at Rocklands Reservoir.

Environmental releases continued with 174 ML delivered from Lake Wartook to the MacKenzie River until releases were ceased mid-August due to naturally occurring flows. 535 ML was delivered from Taylors Lake to the Wimmera River and 500 ML was released from Rocklands Reservoir to the Glenelg River.

Wimmera-Mallee Pipeline supplied Recreation Lakes received 191 ML during the month, and 40 ML was supplied to Wimmera-Mallee Pipeline connected wetlands within the Mallee Catchment Management Authority area.

Consumptive entitlement holders collectively used 770 ML during August to supply urban and rural system demands.

Net evaporation from reservoirs was approximately – 5,550 ML for the month, with rainfall exceeding evaporation. (Net evaporation considers rainfall on the reservoir as an evaporation offset.)

Planned September 2017 Operations

The Bureau of Meteorology in their most recent climate outlook predict average rainfall conditions this spring. Both of Australia’s major climate drivers, El Niño–Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD), remain neutral. This means there is currently no strong indicator for particularly wet or dry conditions.

The Lake Wartook catchment remains saturated after receiving 155 mm of rain during August. When water levels are above its target-filling curve, controlled releases are made to manage the reservoir level. As water is released from Wartook it can be directed a number of ways including to the MacKenzie River, Burnt and Bungalally Creeks, as well as to Green Lake and Taylors Lake. It is expected that regular releases will be made from Lake Wartook during September while rain continues and its catchment remains wet.

Passing flows at Lake Lonsdale are likely to be substituted with releases from Taylors Lake to the Wimmera River. Additional releases may occur from Taylors Lake from time to time to manage water to a safe level.

The routine delivery of water to consumptive entitlement holders will be ongoing.

An operational transfer of 10,000 ML from Rocklands Reservoir to Toolondo Reservoir will conclude in mid-September. This transfer will optimise water levels between the reservoirs to minimise evaporation, and has a secondary benefit of supporting recreational opportunities. The Storage Manager will continue to monitor reservoir levels, with a possibility of an additional transfer of water to Toolondo later in the season if it meets the criteria as described in annual operating plan. 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 September 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.