By Megan Gorrey
Residents on the state’s South Coast are bracing for flash flooding, and Warragamba Dam is expected to spill within hours, as the relentless run of heavy downpours continues to soak parts of NSW.
WaterNSW said on Saturday afternoon the dam, which supplies the bulk of Sydney’s drinking water, was close to capacity after days of persistent rain and would probably spill in the coming hours.
The Warragamba Dam is at capacity. Credit: Nine News
The dam, which is 65 kilometres west of Sydney’s city centre, was holding about 2058 gigalitres of water – more than 99 per cent of its 2069-gigalitre capacity – shortly before 5pm.
WaterNSW said that if the western Sydney catchment received the most likely forecast of 35 millimetres of rain in 48 hours, the dam could reach a peak spill rate of about 40 gigalitres a day.
It prompted a warning for residents to avoid driving, walking or riding through any floodwater.
“If you are downstream of the dam, stay away from fast-flowing or deep water near waterways and floodplains. These hazards potentially threaten the safety of you and your property,” WaterNSW said.
The incessant rains that have drenched Sydney continued unabated on Saturday.Credit: Steven Siewert
The agency said it was likely smaller dams at Cataract, Nepean, Woronora, Tallowa, Greaves Creek, Medlow Bath and Middle Cascades would continue to spill. Avon Dam would also possibly spill.
Sydney’s downpours were heaviest in the eastern suburbs on Saturday. About 30 millimetres of rain fell on Little Bay in the 12 hours to 9pm, while Rose Bay recorded 26 millimetres in the same period. Sydney’s central business district copped about 15 millimetres.
The Bureau of Meteorology said an upper trough bringing rain and thunderstorms to much of NSW meant persistent coastal showers would dampen vast stretches of the east coast over the weekend.
It issued a severe weather warning for heavy rain in the South Coast, Illawarra, Southern Tablelands and Snowy Mountains regions on Saturday night and Sunday morning.
“Heavy rainfall which may lead to flash flooding may develop over the northern parts of the South Coast, southern parts of the Illawarra, eastern parts of the Southern Tablelands and far northeastern parts of Snowy Mountains districts for the rest of Saturday and persist into Sunday,” the bureau said.
Meteorologist Christie Johnson said six-hourly rainfalls of between 50 and 70 millimetres were likely, with some possible downpours of 100 to 120 millimetres.
“This is rainfall falling on already wet grounds, so the water will pool and cause flash flooding. If you’re in these areas, please take care,” Johnson said.
The areas likely to be the hardest hit are Nowra, Batemans Bay, Moruya Heads, Ulladulla, Narooma and Araluen.
The downpours are expected to ease on Sunday evening.
The bureau said rain could cause minor flooding, with some moderate flooding, in parts of the Hawkesbury Nepean Valley, St Georges Basin, Bega and Moruya catchments from late on Saturday.
“People living or working along rivers and streams must monitor the latest weather forecasts and warnings and be ready to move to higher ground should flooding develop,” the bureau said.
The Warragamba Dam on Saturday afternoon. Credit: Nine News
The bureau said a high-pressure system lurking near Tasmania was driving showers onto the NSW coast, bringing moderate to heavy bursts of rain and dangerous surf conditions on Saturday. More rain was predicted for the southern coast of NSW on Sunday.
“The next high-pressure system is forecast to drift across south-east Australia mid-week, promoting a return to somewhat more settled weather,” the bureau said.
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