"It is an extraordinary landscape, but the great thing is resilient residents in the northwest of New South Wales are getting on with life, and ... will cope."
The State Emergency Service said Moree was expected to be isolated for at least 24 hours.
"A lot of it is local water, cutting roads, as the rain has pretty much stopped," spokesman Phil Campbell said.
"That provides us with some confidence that water will begin to fall."
O'Farrell said that although the Mehi River had peaked, the floodwaters would not recede for days.
"The bad news is that peak may stay in place for two to three days.
"Families, businesses, farmers are suffering, and what the SES is saying is that this water is not going to recede in a hurry."
Moree Mayor Katrina Humphries said the town was as ready as possible, with thousands of sandbags put back in place after flooding two months ago.
"Anyone that had water last time knows they're going to have more water," she said.
"Anyone who nearly had water last time knows that they'll probably have water, and anyone that was high and dry has got people in their house."
The air force has diverted a Hercules aircraft from a planned training mission to take supplies, including bedding, to the town.
RAAF aircraft played a crucial role in supporting relief operations in Queensland during floods a year ago, the Defence Department said.
The State Emergency Service said a further 2280 people had been asked to evacuate their homes in Moree, Pallamallawa and Biniguy, east of Moree.
ABout 6525 people were isolated in other parts of the state, including the town of Wee Waa, south of Moree.
Wee Waa, on the Namoi River, would be isolated until Tuesday or Wednesday, the service said.
- AAP
