Floodwaters peak in Forbes, but more wet weather is on its way

State Emergency Service Acting Deputy Commissioner Mark Morrow said the Lachlan River peaked at 10.67 metres between 9pm and 10pm on Sunday, after cumulative rainfall in the region forced evacuation orders to be issued for 1000 people on about 250 properties.

The flooding passed August 1990 levels, when 132 properties were inundated.

The State Emergency Service (SES) is expecting some problems with sewage and power in and around Forbes due to the flooding, and some residents may have to wait days before being able to return home.

While flooding in Forbes has surpassed the 1990 floods, in which the Lachlan River reached 10.65m, the worst could still be to come. The Bureau of Meteorology predicts a second, higher peak near Condobolin and Euabalong this week.

"There is a renewed low-pressure system due to come in later this week," Acting Deputy Commissioner Morrow said on Monday morning.

"There will be downstream flooding effects at  Condobolin and Euabalong on the Lachlan River. They will see major flooding and people will need to start to think about preparing now in those communities ... but of course that low-pressure system will bring renewed rises potentially on the Lachlan River itself in Forbes, and we could see that community subjected to this sort of flooding for the next 10 days to two weeks."

Nick Aisake, from the SES, said there were four flood rescues on Sunday, all involving animals and livestock. He said water from the Lachlan River was starting to spill into Lake Forbes, threatening to cut the town in half.

"There's some water coming into backyards, garages and sheds, but we have no reports of water in houses yet, it hasn't gotten to that stage" he said.

The Bureau of Meteorology also reported major flooding downstream at Condobolin and Euabalong. Mr Aisake said the two towns would feel the full brunt of the second, higher peak by Friday.

Earlier on Sunday, the SES warned against complacency after floodwaters began moving in a different direction to that originally predicted. 

"It isn't behaving like it's previously done, and that's why people are not sure what decisions to make," said Sue Pritchard from the SES.

"We're concerned about the sewerage and other infrastructure failing. People are trying to get to relatives but roads are cut."

Fairfax Media reporter Olivia Grace-Curran, who was evacuated from her home on Saturday, said that the sight of rising floodwaters had driven home the urgency of the situation.

"I can't get to roads where I took photos this morning because they are now completely flooded," she said on Saturday.

"People are beginning to see the water enter town, instead of just hearing about it, and are starting to realise this is serious."

Five Australian Defence Force trucks were assisting with emergency transport in and around Forbes on Sunday. 

More than 2335 requests for assistance had been received by the SES state-wide between August 30 and Sunday afternoon, with the service completing 96 flood rescues.

NSW Deputy Premier Troy Grant warned the flooding will have a long-term impact on farming communities.

"What's coming is worrying the population more than what will happen tomorrow morning," he told Sky News on Saturday.

The town is no stranger to major flooding events, which have fallen at roughly seven-year intervals over the last century.

This story first appeared on The Sydney Morning Herald.