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Drought prevention

Saturday, 9th December, 2017

Lake Menindee in drought in 2010, a plan has been developed to ensure that even if the lakes run dry - human water needs will be met. PICTURE: Gavin Schmidt Lake Menindee in drought in 2010, a plan has been developed to ensure that even if the lakes run dry - human water needs will be met. PICTURE: Gavin Schmidt

Broken Hill and Menindee would receive a continuous flow of water even if there was a repeat of the worst drought on record, according to WaterNSW.

WaterNSW said it had developed a Lower Darling Operations plan to ensure critical human water needs can be met under the worst-case scenario, which it has dubbed “Sahara”.

The “Sahara” scenario is one in which there is no flow at Wilcannia and the water is exhausted.

The Menindee Lakes are now down to 29 per cent of their total storage capacity.

Lake Pamamaroo hold the most, at 89 per cent, Lake Wetherell is at 37 per cent, Lake Menindee 3.5 and Lake Cawndilla 26 although the water in this lake is inaccessible for town supply and is being used by Tandou.

Persistently low inflow into the lakes this year have fallen further in recent months, Water NSW said.

In the five months to November 30 only 55 gigalitres have come down the Barwon-Darling rivers through Mungindi, Brewarrina, Culgoa, Bourke and Wilcannia.

WaterNSW said that 72 per cent of that had reached the lakes. 

For the year so far, 160 GL had come into the river system and 114 GL had reached the lakes, Water NSW said.

“By comparison during the previous six months of 2016 (July to December) the combined total for those locations was 2,381 GL, 85 per cent of which made its way to the lakes,” it said.

Water NSW said that management of the lakes had focussed on taking most of the releases from the lower storages in Menindee and Cawndilla lakes, while holding water in the upper lakes of Wetherell and Pamamaroo. 

It said this would result in 300 GL remaining in the upper lakes when the system fell to the 480 GL mark (predicted for later this month) at which time management of the lakes resorts to NSW. 

Assuming that the low inflows persist, WaterNSW said its plan would ensure that there was enough water in storage to meet demand in Broken Hill.

It said it would also maintain a continual flow of water along the Lower Darling.

Water quality and acceptable salinity levels were also integral components of the plan, Water NSW said. 

The quality of the water left in Lake Wetherell would be the key to alternating supply from Weir 32 to Copi Hollow and from there to Broken Hill.

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