There's one for the 1974 flood, where water reached 12.5m, and one for 2017 when it reached 11.2m, and now, one will be placed much higher.

While the reminders are there that Lismore is the most flood prone city in Australia, what happened on Monday was unimaginable - flood water climbed to a staggering 14.4m, almost two metres above the highest on record.

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In its wake, the flood has left every home in Lismore's basin inundated, and tragically, the police reported the death of an elderly woman found in her home on Tuesday.

Shocking stories are emerging of people spending up to eight hours on their roofs hoping for rescue - not just people, our people who work in hospitals, cut our hair, work in our schools and on our roads.

It sparked an enormous rescue effort as emergency services were joined by locals in tinnies, helping to evacuate people in danger.

An emotional Elma Hancock, resident of South Lismore and Lismore hairdresser, recounted the horror of watching flood water rapidly rise into her home, of spending hours in chest-high water with her family before being rescued.

Once in the tinnie, she tells of the harrowing trip along flooded streets in Lismore - over a flooded Ballina St bridge, ducking under powerlines as they made their way to safe ground near the Second Ave intersection.

She was in tears as she said they had no time to save anything other than the clothes they had on.

"There just wasn't time," she said.

Hundreds of rescues were conducted on Monday and possibly thousands were still waiting to be rescued on Tuesday.

Every business, school, and building in central Lismore , North Lismore, South Lismore, and low-lying areas of East Lismore was inundated.

Lismore Square, Lismore Workers Club, Trinity Catholic College, the Cathedral, were all impacted.

The weather system began early last week with the Bureau of Meteorology warning of flooding in the region. By the end of the week, it looked like Lismore had avoided a major flood, but the SES cautiously warned a massive rain system hitting south-east QLD would be devastating if it were to head south. It did.

By Saturday evening, BoM was warning severe weather would hit Lismore on Sunday night, causing major flooding.

Initial estimates of 10.6m were quickly revised, with new warnings the levee would be overtopped on Monday morning.

As heavy rain fell - more than 1000mm was recorded in 30 hours at Dunoon - BOM continually revised the time it would overtop and the levels the flood would reach.

The levee was breached at about 3am on Monday morning, with floodwater peaking at 14.4m.

Australian Defence forces were mobilised and helped with rescues, both via boat and helicopter.

Floodwater is slowly receding, but still inundating communities south of Lismore.