More than 10,000 people have been isolated by the floods and about 2,000 people are staying in evacuation centers, the Australian Broadcasting Corp. reported.
The northwestern town of Gunnedah was the most recently hit, with the nearby Namoi River having risen to nearly 26 feet.
SES said its top priority was getting food and medical supplies to those in need.
SES northwest incident controller James McTavish said residents in Moree were surprisingly upbeat Friday.
"We had a community meeting and people are despite the impact in the area they're actually quite upbeat," he said. "They are obviously very concerned about their properties. They're very concerned about their community but they're remaining very positive in some very trying circumstances."
McTavish said river levels could take months to go down. Downstream of Moree and into the Darling system, "the flood will continue for many weeks and even months," he said.