Southeastern Australia is braced for more torrential rain and flooding today after record downpours which have forced the evacuation of 1700 people and left hundreds more stranded.

Three-quarters of New South Wales is inundated or threatened by floodwaters, with southern areas particularly hard hit and Canberra also affected. In Victoria, where 100mm of rain was forecast to fall today, people have been frantically sandbagging homes and businesses.

Sydney's main water source, the Warragamba Dam, was expected to overflow late yesterday or early today.

The southeast is experiencing its biggest drenching for decades, more rain falling on Albury, on the NSW-Victorian border, in two days than ever recorded for the month of March. A measuring station in Pooncare, in southwestern NSW, has received half its average rainfall in recent days, with rain still falling.


"We've seen incredible rainfall ... we're breaking daily records," said Alex Zadnik, a senior meteorologist with the forecasting company Weatherzone. He blamed a low-pressure trough moving across the country and warned that, with more heavy downpours forecast, "the situation could still get worse before it gets better".

Twenty-two people have been rescued from rapidly rising floodwaters which caught them unaware. A police officer trying to save a man who had jumped into the Queanbeyan River, near Canberra, ended up clinging to a tree, while another officer got entangled in a submerged fence.

All three were rescued by a State Emergency Service volunteer in a boat.

The capital has already had half its average March rainfall, while a half-built dam near Canberra - planned following a severe drought - is overflowing. The city's water authority, ACTEW, described the flooding as a "construction nightmare".

In southern NSW, the towns of Cowra, Bega, Cooma and Goulburn are worst affected, many residents spending Thursday night in evacuation centres or elsewhere after being ordered to leave their homes. Some had to be rescued by boat after rivers burst their banks.

Flood warnings were issued for the Hawkesbury River area west of Sydney as the Warragamba Dam reached 99.3 per cent capacity last night. Locals had been advised to keep their children off school, and warned that roads were likely to close. About 800 people faced possible evacuation.

Dieter Gescke, deputy commissioner of the NSW State Emergency Service (SES), said the repeated deluges were causing problems. "It's almost a kind of Groundhog Day thing until this [weather] system finally breaks up and dissipates," he said.

Northeastern Victoria, which has had 200mm of rain in the past week, was preparing for another soaking today. Nearly 30,000 sandbags have been brought in by the SES, which has mobilised equipment and personnel. SES spokesman Lachlan Quick said today would be "a day of pretty significant concern".


Peter Chiswell, publican of the Tungamah Hotel near the Victoria-NSW border, said: "Four or five years ago, we were talking about being burned out and droughted out, and here we are now being flooded out."

In another small Victorian town, Tallygaroopna north of Shepparton, five houses and the pub were under water.

A group of schoolchildren stranded overnight on Mt Buffalo, in Victoria's alpine region, were rescued yesterday. The 28 students and two teachers spent the night at a mountain lodge after the only access road was blocked by falling boulders and trees.

In western NSW, a flood warning was issued for Bathurst, where the Macquarie River was expected to peak last night, and motorists were urged to avoid travelling in the area.