Residents in the Hewitts Creek catchment in Thirroul and Bulli say they are being punished by a confusing and flawed approach to flood modelling, which has restricted home renovations and sent insurance premiums through the roof.
They say the exaggerated flood risk modelling meant they have to build "Noah's Ark" if they want to renovate.
They are among many residents of the Wollongong area whose properties are affected by the application of controversial flood modelling to their neighbourhoods.
Saturday's Mercury revealed how residents of Figtree were being forced to live under a high-risk flood zoning despite their properties never having flooded, because Wollongong City Council's flood mapping assumes every culvert beneath the F6 freeway would be 100 per cent blocked in any large flood event.
This blanket approach has been criticised by an expert engineer from consulting firm Cardno, who argued in 2009 that the policy was "overly prescriptive", outdated and out of step with how other councils balanced development and flood risks.
In Wollongong's northern suburbs, residents have found long delays in flood mitigation works compound modelling problems.
On Hewitts Avenue, Thirroul, residents are in limbo as the whole Hewitts Creek flood study, from 2002, is being done again. This is because of developments in the area, such as the bridge at the base of Bulli Pass, Stockland's McCauleys development, land acquisitions, improvements in modelling technology, and inaccurate measuring of the bridge over Hewitts Creek.
The new study also shows the area under the bridge was under-calculated by more than a third. The new calculations determine the flow can rise by an extra 35 per cent, meaning the modelled water levels nearby drop significantly.
The amount of blockage the bridge experiences is also being revised. It was listed as being 20 per cent blocked by the flooding in 1998, but this has been corrected to zero in the new study.
Together, the difference can be two metres in the depth of water predicted to flow over some properties under the modelling.
At a consultation meeting on the new study, held in Bulli this month, residents made their concerns clear to council representatives.
Raquel Carabine wants to build a granny flat at her house but has been told she must build it several metres off the ground to get it above the projected flood levels.
But differing water levels have been given to residents, and the old study will soon be replaced by new sets of figures.
Ms Carabine says the main flood risk for Hewitts Avenue comes from Woodlands Creek, which must flow through a small culvert to get under the railway line. Beyond the railway are the wide, modern and effective channels built through Stockland's McCauleys development.
She said major works had taken place on the Princes Highway nearby, and McCauleys, but the creek in between was still clogged with vegetation and must pass through a small culvert to get under the railway line.
"It seems like they're washing their hands of it and putting the flood risk on to the residents," she said.
"We've had two major developments happen either side, and in the middle there's this little section that couldn't get cleaned out.
"They allowed development in this street in the first place - now all they're doing is imposing higher and higher flood risk.
Because it is less than six metres across, the Woodlands Creek culvert is assumed to be 100 per cent blocked in flood modelling.
Vital works listed as "high priority" in the 2002 Hewitts Creek Floodplain Risk Management Plan - modification to the truck safety ramp, and a levee bank on the north side of Woodlands Creek - were together priced at just $173,000. But neither has been done.
Installation of a high-flow culvert or bridge to take Woodlands Creek under the rail line, priced in 2002 at $640,000 and also identified as a high priority, has not been done. The council now estimates these culverts as costing several million dollars, and is reviewing when - or if - it should build them.
The new Hewitts Creek study has not been finalised, nor turned into a plan for action. The draft may be accepted by the council in February, then finalised, and then reworked into a management plan with recommendations for action.
Meantime, residents are still bound by the conclusions of the 2002 study, with some insurance premiums multiplied by the phantom flood levels.
Resident Jeff Body said he would love to do some renovations on his house, but the insurance had doubled in the past three years, while the prolonged decision-making goes through another flood study process. He doesn't want to do work, only to find the rules changed by the new study. But he's not holding his breath for mitigation works.
"If we see anything done by 2018 we'd be surprised," he said.