Deputy mayor says the Hunter River rock platform will bring "a really big" flood risk to Maitland

Councillor Mitchell Griffin is concerned the rock platform will put Maitland - a city of close to 100,000 people - at risk.

He thinks its "quite likely" Maitland CBD would have "gone under water" if a rock platform had been in place when the Pasha Bulker storm hit in June 2007 and he is worried it would affect a lot more properties and lead to prolonged road closures.

The 2007 flood was the last time the Belmore Bridge's 'major flood' level of 10.5 metres was breached. Hundreds of people in Lorn and Central Maitland were told to evacuate and the army was called in to help sandbag shops in The Levee.

Cr Griffin said residents had already raised "serious concerns" about flooding in Millers Forest, Raymond Terrace, Woodberry and Tarro during a community meeting about the platform last month but he said the effect was even broader than that.

He said Morpeth, Phoenix Park and Largs and low-lying areas of Central Maitland would also be effected, and areas upstream of Maitland wouldn't escape the impact.

"It's going to form a barrier within the Hunter River," he said.

"A lot of floodwater from Maitland goes out through that particular river so effectively damming part of that river is a really big risk to the rest of Maitland."

Cr Griffin will call on his fellow councillors at Tuesday's council meeting to support a push for an alternate plan that won't impede the river.

Transport for NSW says a flood would have a minor impact on properties upstream.

The 180-metre rock platform wasn't part of the original plan and will have to be approved. It would be built on the western side of the river at Tarro, upstream from the Hexham Bridge, and then removed and relocated to the eastern side. It would be removed once the new bridge was finished.

Councillor Griffin wants the council to write to relevant state and federal ministers including Paterson MP Meryl Swanson, Maitland MP Jenny Aitchison, Newcastle MP Tim Crakanthorp, Port Stephens MP Kate Washington and Upper Hunter MP Dave Layzell and express concerns about the use of the platform.

He wants the lack of consultation with the community, NSW State Emergency Service (SES) and the effected councils made clear, and he wants the impact on suburbs west of Berry Park to be considered.

Cr Griffin is also concerned about residents being able to access insurance and government grants if a flood happened while the rock platform was in place. He said this could be a grey area due to "the potential man-made effects on flooding".

Millers Forest cattle farmer Gloria Green has welcomed Cr Griffin's support and will speak at the council meeting about his motion.

She is leading the charge to raise awareness about the rock platform and is fighting to stop it.

She said the agriculture industry would take a big hit with pastures inundated for a longer period of time and higher flood levels which could leave livestock without higher ground.

"At the meeting we found out this rock wall is going to be around for 22 months. We can't afford to take that sort of a risk. It's our livelihood," Mrs Green said.

"If we get a flood it'll go into homes where it normally wouldn't, it'll have a vast impact but Transport for NSW seems to think it's only a small number of individuals who will be effected."

Transport for NSW was initially going to use a pontoon to help crews construct the new bridge. This was included in the original plan. Since then they have decided that a rock platform would be a safer option for workers.