Raising the wall of the Warragamba Dam in western Sydney is the “most effective means” of protecting the Hawkesbury Nepean community, according to Insurance Council of Australia (ICA) GM Risk Karl Sullivan.

A NSW Legislative Council select committee is planning to hold hearings next month on the proposal to raise the dam wall.

“The proposed mitigation involves raising the existing dam wall by 14 metres to create a flood mitigation zone,” Mr Sullivan says in a post on his LinkedIn account.

“As ICA understands things, this zone is not intended to be used for water storage, and appropriately drafted legislation could ensure this does not occur.

“Therefore, the proposed flood mitigation zone would only ever be fully inundated during a significant event when the alternative to the proposed mitigation is catastrophic flooding of the Hawkesbury Nepean Basin.”

His LinkedIn post reaffirms ICA’s position on the matter in a submission to a NSW parliamentary inquiry

At present nearly 40,000 properties are exposed to some level of flooding, and premiums for insurance with flood cover included in locations facing extreme risk can be more than nine times above the national median.

“Many insurers describe the existing flood risk on the Hawkesbury Nepean floodplain as the most significant and unmitigated community flood exposure in the country,” Mr Sullivan says.

“However, the flood exposure these communities face can be significantly reduced, in some cases entirely negated, through permanent mitigation.”

Environmental and community groups have voiced concerns the proposed wall raising plan would impact the surrounding landscape and sites of cultural significance.

ICA has, in its submission to the NSW parliamentary inquiry, voiced concerns at “significant misunderstanding or over-estimation” in the community over the impact on surrounding landscape.

“Decisions that could lead to rare flooding of environmental resources are fundamentally regrettable to all but must be balanced against the greater community need,” the submission says.

“Where sound analysis shows that there are no reasonable alternatives, those difficult decisions must be made in a timely fashion in order for work to commence in time for lives to be saved and property protected before the next serious flood event.”