Emergency services in New South Wales are facing the largest flood operation in the state's history as more defence force personnel and volunteers from around the world join rescue and relief efforts.
Hundreds more homes are expected to go under this week and more than 1,000 people have been evacuated as flood levels rose faster than expected overnight on Monday.
Volunteers are coming from New Zealand, the US, and Singapore.
"We've had overseas volunteers from right around the world when it comes to fighting fires but my understanding is this is the first time we've had it with floods and I want to thank them," NSW Premier Dominic Perrottet said.
Upwards of 200 people have been rescued from floodwater in the past 24 hours since Monday morning and the State Emergency Service has received more than 900 calls for help.
Police appeal for details on missing people
Searches are underway for two people who are believed missing in floodwaters in Eugowra in the Central West.
Police are appealing for information to try and find Ljubisa 'Les' Vugec, 85, who was last seen at a home in Evelyn Street about 9am on Monday.
Police said they had serious concerns for his welfare.
A search is also underway for 60-year-old Dianne Smith, who last spoke to a relative from in a car in Eugowra about 9.30am Monday.
Police said relatives had not been able to contact her again.
Eugowra, a half-hour drive east of Forbes, was hit by major flooding on Sunday and Monday.
Some residents have started returning to their homes on Tuesday to collect belongings, but are being warned some houses will have to be demolished due to the extent of the damage.
Forbes in 'shock'
The town of Forbes is facing its second flood emergency in just two weeks as the Lachlan River continues to rise and is expected to reach 10.8 metres Tuesady afternoon.
An emergency evacuation order was issued to residents this morning as water rose faster than expected.
The Iron Bridge at Forbes hit major flood levels earlier Tuesday and is currently sitting at 10.65 metres.
Forbes mayor Phyllis Miller said the feeling on the ground was disbelief.
"I think they're quite shocked," she said.
"They can't believe this could happen twice in such a short period of time."
Forbes faced a major flood emergency and evacuations just two weeks ago.
Follow our live flood coverage here
Jamie Loomes runs a fuel and grocery store on higher ground in the north of Forbes and has not had to evacuate.
Mr Loomes said the town was feeling "nervous" and "exhausted" as the historic flood peak loomed.
He said since the evacuation warnings came on Monday, the town had been buzzing with people preparing or evacuating.
"We're flat out because everyone in town is stocking up on supplies," he said.
"Since yesterday [Monday] in town it's just been like ants going around everywhere — everyone's going somewhere."
But since the Lachlan River broke its banks and isolated the Forbes CBD this morning, Mr Loomes said things had slowed down.
"The traffic here was unbelievable but as soon as [floodwaters] cut the town the traffic slowed down," he said.
Mr Loomes said another major flooding event less than two weeks after the last was a blow to residents, but meant they were more prepared than last time.
"We've had a couple of days' notice and having that practice run two weeks ago has helped," he said.
Wyangala Dam upstream on the Lachlan River was spilling at 230,000 megalitres per day on Monday.
The spill has now dropped to 60,000ML, but the impact is still being felt in Forbes and other towns further downstream.
NSW State Emergency Service (SES) spokesperson Andy Edmonds said the evacuation in Forbes was brought forward by faster-rising river levels than initially forecast.
River runs backwards, creates cliff
A sheer cliff face has appeared Monday night in Wellington, where floodwaters have torn into the riverbank near the Duke of Wellington Bridge, eroding the bank within hours.
Resident Dianne McGlinn said the Bell River was flowing so ferociously on Monday that it overpowered the Macquarie River.
"The Macquarie was actually moving backwards because of the force coming through from the Bell River. It was incredible," Ms McGlinn said.
"It's funny when you see a river go backwards. It's not normal."
Hundreds of warnings across the state
More than 100 warnings remain in place across the state.
NSW Minister for Emergency Services Steph Cooke said there were currently around 1,000 properties and hundreds of people covered by current evacuation orders around Forbes and other parts of the Central West.
"We are expecting 500 to 600 homes to be inundated," Ms Cooke said.
In the Riverina, residents in Maude have been told it is too late to leave, with local roads around the village likely to be cut off.
Communities at Collarenebri, Lightning Ridge, Tilpa, and Weilmoringle remain isolated.
Brewarrina can still be accessed by trucks.
Meanwhile, the Lachlan River in Condobolin has risen to 7.36m, just below the 1952 record of 7.37m.
It is expected to exceed the record sometime Tuesday.
The town of Cowra remains cut off after the Cowra Bridge was closed last night as access roads were inundated by floodwater.
