Joining the premier is Water NSW chief executive Andrew George, who says Warragamba Dam – which supplies much of Sydney’s drinking water – is expected to spill on Monday, once the rain moves on.
George said the dam was currently at 96.3 per cent of capacity, meaning it requires about 90 millimetres of rain to fill and then spill.
The Warragamba Dam, which supplies a large proportion of Sydney’s drinking water. Credit: Nikki Short
The Bureau of Meteorology is expecting 100 to 150 millimetres of rainfall over the dam’s catchment during the rain event.
“That means the Warragamba will move into a spill, likely Monday morning,” George said. “What’s important about that is that the spill will occur likely when the rainfall event has moved on, so it is very important that the community remain vigilant.”
Premier Chris Minns said the government and SES was remaining vigilant, and there were processes in place for a controlled spillage of Warragamba “if it hits a certain amount of rainfall”.
He said he didn’t want “to tread over old history” with the now-abandoned plan to raise the dam.
“Any local in the Hawkesbury-Nepean catchment will tell you is that you’ve got [rivers and creeks] … that flood independent to what happens at Warragamba Dam,” he said. “I’ve got to make decisions about what’s in the best interests of those communities. And it’s important to note that those tributaries and rivers will flood in any event when you’ve got moderate to severe weather events like we’re seeing.”