Sydney weather: Warragamba to spill, trigger Nepean Hawkesbury flooding

Warragamba Dam during an earlier spill. Torrential rain caused havoc in the Illawarra over the past 24 hours with numerous roads, including the Mount Brandon Road in Jerrara, closed because of flooding. Photo: Sylvia Liber
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Jamberoo Road was among the roads flooded in the past 24 hours. Photo: Sylvia Liber

Warragamba Dam, Sydney’s main reservoir, will begin spilling on Wednesday night for the first time in two years, leading to minor flooding downstream in the Nepean Hawkesbury Valley, the Bureau of Meteorology said.

The level of Lake Burragorang was about 1.2 metres below the spill level as of early Wednesday afternoon, with the height likely to rise further as flows resulting from the east coast low reached the dam, said Hugh Bruist, a senior bureau hydrologist.

About 160 millimetres of rain fell into the Wollondilly River catchment upstream of Warragamba in the 48 hours to 9am on Wednesday, the bureau said. \n”,colour:”water”, title:””, maxWidth:200, open:0}] );}if (!window.googleMaps_Icons) window.googleMaps_Icons = {};window.googleMaps_Icons[“water”] = {“marker”:{“image”:”http://maps.gstatic上海夜网m/mapfiles/ms2/micons/water.png”},”shadow”:{“image”:”http://maps.gstatic上海夜网m/mapfiles/ms2/micons/water.shadow.png”}};if (!window.gmapsLoaders) window.gmapsLoaders = [];window.gmapsLoaders.push(CreateGMapgmap2015726144453);window.gmapsAutoload=true;/*]]>*/]]>

Meanwhile a minor flood warning was issued for the Nepean-Hawkesbury Valley after 170mm of rainfall in the valley resulted in spills from the Nepean and Avon Dams.

“Landowners should begin preparation for minor flooding. Pumps and other portable assets in low lying areas should be relocated. Livestock should be moved to higher ground,” the SES said.

Rising waters are expected to trigger minor flooding at Menangle from midnight Wednesday.

Warragamba Dam is expected to start spilling early on Thursday morning for the first time since June 2013.

“At this stage minor flood peaks downstream of Warragamba Dam are expected to be similar to the March 2012 event,” the bureau said in an updated alert.

Penrith is now expected to see a peak of 5 metres by about noon on Thursday with minor flooding, with the peak at North Richmond likely to reach 8 metres by about 6 pm on Thursday, the update said. Windsor should also receive minor flooding, with a peak at about 6 metres three hours later.

Flooding in NSW’s south-east

An intense low pressure system sat off the coast south of Sydney most of Tuesday, directing heavy falls over the region.

The St Georges Basin had moderate to major flooding as of Wednesday afternoon, the bureau said in a separate statement.

A flood peak is expected at Sussex during the late afternoon coinciding with the high tide.

Moderate flooding is also taking place along the Lower Shoalhaven River at Nowra and Terara, the bureau stated.

Tomerong, about 180 kilometres south of Sydney, received 439 millimetres of rain in two days, while Nowra copped 390 millimetres and Kiama 336 millimetres, the bureau said.


The bureau was reassessing its estimates for Warragamba after flood levels on the Jooriland River upstream of Lake Burragorang peaked higher than expected, Mr Bruist said.

“It’s quite difficult to assess how much is coming into the system and how it will behave,” Mr Bruist said.

Rain over the Lake Burragorang catchment eased from early on Wednesday morning, Mr Bruist said.

Forecast models suggest the rain belt “should die off”, he said, adding that no further rain was expected to aggravate conditions.