The Bureau of Meteorology is predicting the flood situation in south-western New South Wales to worsen, with warnings stepped up on Thursday.
Around 75 per cent of the state is flooded or under threat, while the record rain has created similar emergencies across the ACT and northern Victoria.
Police in Goulburn have knocked on doors and asking people to leave their homes as heavy rain is leading to rises in the Wollondilly and Mulwaree rivers.
While about 200 homes in the city are subject to evacuation orders, hundreds more are subject to evacuation orders at Cooma in the state's south.
The SES has helped to sandbag low-lying areas in both towns and say it is now a matter of waiting to see how much more rain falls.
The Warragamba Dam west of Sydney is expected to reach capacity and spill water for the first time in more than 10 years.
In the saturated Riverina, many smaller creeks have burst their banks and several towns have been inundated in parts.
Numerous roads remain closed and a moderate flood warning is in place for both the Tumut and Murrumbidgee rivers.
Several people were rescued in the biggest flooding to hit the southern town of Tumut in forty years after the Goobarragandra River peaked suddenly.
Some centres have received about 100 millimetres of rain this week, and for some in the region there is still plenty more to come.
Low-lying streets of Queanbeyan are on an evacuation alert as the Molonglo and Queanbeyan rivers continue to rise, but residents did not seem too fazed, having experienced far worse flooding just 14 months ago.
Gundagai is expected to reach minor flood level and will reach a moderate flood level on Friday morning, and Wagga Wagga is now expected to reach the minor flood level on Saturday night.
'We're not past the worst'
Across the border, communities in northern Victoria spent the day filling sandbags as flood waters continue to rise.
The SES has responded to 182 calls for help in north-east Victoria, including 75 around Yarrawonga.
SES regional officer Keith O'Brien says there has been widespread flash flooding across the region.
"We're not past the worst of the rain there and we probably won't see the end of that until close to midnight tonight," he said.
A prepare-to-evacuate order had been in place for Tallygaroopna all day but few people have left the town.
Dam wall at risk
In Canberra, the main concern is the Cotter Dam construction site, with the new dam wall expected to be overrun by floodwaters soon.
Managing director Mark Sullivan says equipment has been moved or tied down to stop it being swept away.
"This is quite a dramatic thing for a construction site and we are hoping that we have taken every precaution that we can," he said.
Lake Burley Griffin has been closed to the general public after stormwater forced the Queanbeyan treatment plant to go on "bypass".
Council spokesman Ricky Tozer says partially treated sewage has been released into the river.
"We're treating the effluent as it comes in, and then it's being discharged into the river. It's definitely not untreated," he said.
© ABC 2012
13:51 EST Southeast Queensland has been engulfed by heavy rain due to an east coast low.