WaterNSW has said it will gradually increase releases from Menindee Lakes in preparation for increasing amounts of water continuing to flow into the large lake system in the next few weeks, in due to heavy rain and flooding in the northern basin.
The lakes hold 1731 gigalitres (GL) at capacity. They currently sit at 106.75% of storage capacity, since February thanks to high inflows from the continuing weather events across Western NSW.
The lakes have received almost 7060 GL of inflow this year, which is the equivalent of four times the storage capacity of the lakes.
Modelling just released by WaterNSW suggests at least a further 2300-2700 GL is set to arrive between now and the end of December, increasing the risk of flooding in the Menindee area and downstream too.
As an example, the peak flow rate expected at Wilcannia in coming weeks looks likely to be the highest in decades.
A meeting this past Friday, WaterNSW informed a multi-agency community meeting – that releases would increase gradually from the main weir to eventually target 9.6 metres at Menindee and a flow rate of about 36 GL/day at Weir 32.
The plan is to maintain this storage capacity now to capture the higher peak expected later in December, so that downstream flooding impacts can be minimised.
The government body says planning will also take into account uncertainty about volumes of water on the northern flood plain and the contribution of the Tallywalka into the Lower Darling.
Significantly, WaterNSW is expecting at least a further 2000-2300 GL to arrive to Wilcannia between now and the end of the year.
“We are unable to forecast exact volumes at this time as a large proportion of the upstream flows are extending over floodplains in the tributaries and along the river, with further rainfall forecast throughout the catchments,” said a WaterNSW spokesperson.
For updates and to stay abreast of all the information at the links below.
NSW SES – https://www.ses.nsw.gov.au/