Warragamba Dam spills over as flash flooding warning issued for NSW South Coast

The state’s wet streak has caused Sydney’s major water supply, Warragamba Dam, to overflow for the second time this year.

The dam, which is four times the size of Sydney Harbour, began spilling over at 7.30am on Sunday.

Warragamba Dam tips over capacity on Sunday morning.Credit: Dean Sewell

“It was a slow build-up with lighter than expected rain over [Friday and Saturday] in the catchment area,” a WaterNSW spokesman said.

“We expect the spill to go for a few days at least, but it’s not a very large spill. It won’t be as large as the one last month, which peaked at 220 gigalitres a day. We were predicting this one would be 30 to 40 gigalitres a day, based on the lower end of the forecast.”

Warragamba, whose capacity is 2065 gigalitres, is located 30 minutes’ drive south-west of Penrith and supplies water to more than 5 million people in Sydney and its surrounds.

The dam was on Sunday spilling at a rate of 6.5 gigalitres per day and increasing, according to WaterNSW. It said other smaller dams in Greater Sydney were also continuing to exceed capacity, among them Cataract, Nepean, Woronora, Tallowa, Greaves Creek, Medlow Bath and Middle Cascades.

The overflow came as the Bureau of Meteorology issued a severe weather warning for the NSW South Coast, Southern Tablelands and Snowy Mountains, which was cancelled soon after 3pm.

The bureau forecast heavy rainfall on Sunday, leading to possible flash flooding, listing potentially affected areas as Nowra, Batemans Bay, Moruya Heads, Ulladulla, Narooma and Araluen, but the heavy rainfall had eased in the regions south of Sydney by mid-afternoon.

A minor flood warning remained in place for the Hawkesbury Nepean Valley and the South Coast on Sunday afternoon, with the NSW State Emergency Service advising against driving, riding or walking through flood water, to stay away from creeks and storm drains and to take refuge in the highest spot available if trapped by flash flooding.

The SES on Sunday advised of possible flooding of the Deua Rivers at Wamban, the Bega River at Bega, the Colo River at Colo, the Hawkesbury River at North Richmond and the Upper Nepean River at Menangle.

Sydney recorded 31 millimetres of rain in the 24 hours to Sunday morning, but the further rain forecasted did not eventuate, with the city seeing less than a millimetre during the day.

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