BUSINESSMAN Brad Zanow and academic Marie Cavanagh are leading a campaign to halt changes to Ipswich's flood line to the 1974 level.
They say Ipswich City Council is planning to make the line permanent without waiting for a flood study to be conducted.
Few people are aware of the situation and it could affect 7000 properties in Ipswich, they say.
After the 2011 flood, they say, the council put a temporary flood line in its planning scheme which in most areas of the city is equivalent to the 1974 flood line.
The height of this line is about 4m higher than the flood line shown in the 2004 planning scheme and 2m higher than the 2011 flood.
"The council is saying that the Flood Commission said this is the right thing to do but this is incorrect," Mr Zanow said.
"The Flood Commission has said that the line is okay as a temporary measure only until the council has done comprehensive studies to establish what the flood regulation lines and risk levels should be. Most people don't know about this until they go to sell their house or subdivide their land or renew their insurance."
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Dr Cavanagh is urging people to make submissions to Ipswich City Council before June 10.
"I think the issue is, we need to get people to respond to the council's request for submissions as to why this TLPI (Temporary Local Planning Instrument) should not become permanent at this stage," Dr Cavanagh said.
"The Flood Commission said it was prudent to do that but only after a full study was done.
"The decision the council says it's going to make is premature given the Flood Commission recommended a full study be done first.
"There is a lot of anguish among residents. My perspective is making sure processes are followed and the council listens to us."
Bundamba resident Robert Bolton, 61, said his house was now below the 1974 level after being above the Q100 line when he bought it. Mr Bolton says he bought his house in Andrew St less than seven years ago for $465,000 and now it is valued at between $285,000 and $312,000.
"I can't get flood insurance," he said. "It went from $1240 a year to... the smallest quote I got was $5800 and that only covered for certain types of flood."