Hawkesbury Council has voted against tougher flood rules, rejecting a push to raise the Flood Planning Level to a 1-in-200-year event. In a split decision, councillors chose to stick with the current 1-in-100-year standard, despite expert advice urging an increase.

The decision came as part of the Hawkesbury Floodplain Risk Management Study and Plan 2025, a key document meant to guide planning and flood resilience in the region. While Council adopted the study at its March meeting, a majority of councillors blocked the recommendation to tighten flood controls - overlooking warnings about increased flood damage and risk to thousands of homes.

The study, based on data from the recently released Hawkesbury-Nepean River Flood Study 2024, outlines various flood mitigation measures. Public exhibition of the draft plan ran for eight weeks, with Council receiving 70 responses, including just 10 written submissions, 46 comments on the "Your Hawkesbury - Your Say" platform, and 14 pinpoint map comments.

A key recommendation of the draft study was to increase the Flood Planning Level. This level determines where flood-related development controls apply, currently set at the 1% (1-in-100-year) Annual Exceedance Probability (AEP) flood level. The study proposed a shift to the 0.5% (1-in-200-year) AEP level plus 0.5 metres, which in Windsor would raise the Flood Planning Level from 17.2 Australian Height Datum (AHD) to 19.2 AHD.

The study found that a 1-in-100-year flood event would impact 5,388 properties, causing damages of nearly $2 billion. In a 1-in-200-year event, 7,211 properties would be affected, with damages exceeding $2.9 billion. “It highlights that an additional 1,823 properties are affected in a 0.5% (1 in 200) AEP flood event compared to the 1 in 100,” the study stated.

In submissions, residents expressed concerns that raising the Flood Planning Level could affect insurance availability, property values and future development controls relating to existing development. The study also found that proposed levees and bypasses were not viable due to high costs and low benefit-to-cost ratios.

Councillor Nathan Zamprogno opposed the change, citing concerns about insurance costs. “Many residents I speak to find it increasingly difficult to access and then pay for insurance. When the government says 'don't build here,' insurers take note and jack up their premiums because our policies give a green light to insurers to declare some homes to be at such a risk they refuse to insure, or offer 'go away' quotations like $20,000 per year.”

Zamprogno supported the study overall but said, “The costs of sending a signal concerning flood risk and the impacts on insurance were not something I could ignore. Council staff in their responses to these concerns effectively tried to say that insurers don't pay attention to what Councils do when defining and proclaiming risk. I disagreed.” He cited the Insurance Council of Australia’s fact sheet, which states that insurers consider multiple sources, including local government flood mapping, when assessing risk.

“I don't want people to build in flood-prone areas, and the existing rules already ban it. It’s madness to let Sydney’s pressure for development override our common sense about flood risk,” Zamprogno said.

Councillor Mary Lyons-Buckett strongly disagreed with the decision. “The recommendations put forward gave us the opportunity to be a part of the change we badly need to investigate; options which would decrease our vulnerability to flooding into the future: house-raising, buybacks, changes to planning controls, effective evacuation routes.”

She argued that the proposed 1-in-200-year flood planning level was a reasonable measure. “This would apply to future new developments in that flood planning area requiring habitable space to be slightly higher and encouraging other aspects of construction such as design and materials to be as flood resilient as possible. This change would not alter any land use zoning. This change would not prevent development, nor prohibit renovations, extensions, or redevelopments of existing properties in the designated flood planning area.”

Lyons-Buckett warned that ignoring expert advice could have serious consequences. “Ignoring expert advice designed to enhance flood resilience is potentially negligent. It is very disappointing to have heard years of calls for doing whatever we can to reduce risk to lives, only to have such an opportunity discarded. As leaders, we should be strengthening flood resilience, not clinging to outdated approaches that leave our community vulnerable and potentially expose us to liability in the future.”

Despite rejecting the increased Flood Planning Level, Council included additional flood mitigation measures in the final report, such as road improvements for evacuation and enhanced data collection following flood events.

Voting in favour of adopting the full study, including the increased Flood Planning Level, were Councillors Mary Lyons-Buckett, Peter Ryan, Danielle Wheeler, and Amanda Kotlash. The remaining eight councillors - Les Sheather, Paul Veigel, Shane Djuric, Eddie Dogramachi, Mike Creed, Jill Reardon, Nathan Zamprogno and Sarah McMahon successfully voted to exclude planning controls from the mitigation measures.