(CNN) -- Heavy rains left thousands stranded in eastern Australia on Saturday as authorities warned of more flooding and urged several communities to flee to higher ground.
About 16,500 people are isolated because of flooding in New South Wales, with evacuation orders in place for several communities, the New South Wales Emergency Services said.
In the neighboring state of Queensland, authorities issued flood warnings for three towns, Surat, Roma and Mitchell, and warned residents living downstream of rivers to move to higher ground.
Residents of the southwestern Queensland town of Charleville are hoping that its protective levees will hold back the rising waters.
Emergency officials ordered evacuations early Saturday as they warned that the river was expected to top the levee banks within 12 hours.
Food and medical supplies have been flown to isolated communities elsewhere in Queensland.
In New South Wales, officials issued natural disaster declarations for several areas.
Flood waters have started to recede around North Moree after five days of major flooding, the New South Wales Emergency Services said, but many of the town's streets remain closed.
Aerial assessments show some 300 homes and businesses have been inundated -- making it the worst flooding in nearly 60 years, CNN affiliate Seven Network reported.
The State Emergency Service carried out 18 flood rescues from Friday to Saturday, Seven Network reported, including half a dozen people stuck on a shed roof near Moree with snakes swimming underneath them.
The airline Qantas put on a special flight to Moree on Saturday with supplies of fresh food and milk, the network added.
Major flooding has also affected communities along the Namoi River, leading to the rescue of at least one person trapped in a vehicle on a flooded bridge.
The town of Wee Waa is cut off, with all roads made impassable by flood water and the local airport also out of action, the New South Wales Emergency Services said. Major flooding is expected to continue there until the middle of next week.
Other communities affected by the Namoi River include Boggoabri, Narrabri Bugilbone and Goangra, with flood waters closing roads and inundating some rural properties..
Emergency officials urged people not to walk, ride or drive through flood waters, as this is the main cause of death and injury during floods.