"There is a significant amount of water coming down those river systems now."
Three hundred properties in Lockhart and another 240 properties in Yoogali Village, west of Wagga Wagga, were evacuated overnight.
People at another 620 properties in the two towns are being told to prepare for possible evacuation.
Southwest of Wagga Wagga, residents of The Rock were told to evacuate on Sunday morning as flash flooding hit properties and inundated swollen creeks.
Northwest of Wagga Wagga, an evacuation order was issued for people in Jugiong at 10am on Sunday (local time).
Wagga Wagga is experiencing minor flooding while to the west, Tumut is being hit with moderate flooding.
The Murrumbidgee River at Gundagai is expected to reach 9.6 metres due to heavy local rainfall and increased spill from the Burrinjuck Dam, the Bureau of Meteorology says.
The BoM says it's not possible to predict some flood peaks due to uncertainty over how much more rain is still to come.
In the state's central west, 30,000 sheep are under threat due to floodwaters inundating property near Ivanhoe.
One home has been inundated near Ivanhoe and the SES carried out five flood rescues within 45 minutes on Sunday morning involving vehicles trapped in fast rising floodwaters.
West of Sydney another 265 properties are under a warning in parts of Forbes.
Flash flooding, rising rivers and heavy rain triggered 265 calls to the SES for help overnight, as volunteers carried out 29 rescues.
But there is some good news.
About 2000 people in Sydney's flood-threatened northwest are expected to head back to their homes on Sunday as evacuation orders are lifted on the Hawkesbury-Nepean River, the SES says.
The North Richmond and Windsor Bridges have been reopened to traffic but the Yarramundi and Cattai Bridge remain closed.
And with rainfall expected to ease around Goulburn, it's been removed from the Flood Watch.
"This means that it is now safe to return to Goulburn," Mr Owens said.
"People with access to transport can return to their properties now."
On the downside, Salvation Army emergency services coordinator Norm Archer says volunteers are preparing for more rain in the coming days.
"The sheer size of these floods is something I haven't seen in NSW for many years," he said.
"It's an enormous area that's affected."
Volunteers are operating evacuation centres in the Hawkesbury, Cowra, Cooma, Goulburn, Queanbeyan and Bega.
"Warragamba Dam has now spilled over and around 1000 people have been evacuated in Western Sydney but we have three centres taking evacuees," Mr Archer said.
"We are also on high alert across the rest of the state."
-AAP
