Ballina put three flood maps on exhibition in one night, and they are about the rain rather than the river

What was resolved

Two resolutions, both moved by Cr Erin Karsten and seconded by Cr Michelle Bailey, both carried unanimously.

A fourth study is coming. The report states that The Lennox Head Overland Flood Study is still being finalised and will be reported separately to a future Council meeting.

Overland flooding is a different thing, and the council says so plainly

The distinction is the reason these studies exist. Regional catchment flooding from the Richmond and its tributary creeks, the report says, has been the focus of Council's flood studies and flood risk management planning for many years and is now well understood. Local overland flooding is different. It occurs when intense rainfall generates stormwater runoff that exceeds the capacity of local drainage systems and flows overland through streets, properties and low-lying areas.

Then the evidence, and it is the sentence worth carrying away: The March 2022 rainfall event demonstrated this issue, with overland flooding occurring in several urban areas of Ballina Shire, even though Richmond River flooding was relatively minor compared with the February 2022 flood.

February 2022 is the flood everyone in the Northern Rivers can date. March 2022 is the one that flooded parts of Ballina Shire without the river doing much, and a river study cannot see it.

Why older suburbs carry more of this risk

The report is specific about where the problem concentrates: In older urban areas, the minor and major drainage system approach was not always applied. Many areas rely mainly on piped drainage, with limited or no designated overland flow paths.

Put plainly, newer estates are designed so that water which beats the pipes has somewhere to go. In older streets it may not have been, so it goes through properties instead. For new development the council's standard requires the piped and overland system together to handle a 1% AEP event.

The council corrects the one-in-a-hundred-years mistake itself

Worth quoting because almost every public conversation about flooding gets it wrong. The 1% AEP event should not be read as a flood that only occurs once every 100 years, but rather as an event that has a 1% chance of being exceeded in any year.

The flood function mapping is the one with teeth

The 2023 Ballina flood study, the report notes, did not include flood function mapping. That matters because, in the council's words, flood function mapping is now required to support Council's assessment of development applications, planning proposals, strategic land use planning and infrastructure planning, particularly in response to Clause 5.21 of the Ballina Local Environmental Plan 2012.

That clause is the reason the mapping has teeth. The report says Clause 5.21 places greater emphasis on minimising risk to life and property, ensuring safe evacuation, avoiding development that is incompatible with flood function and behaviour, protecting environmental values, and considering flood impacts associated with climate change. Avoiding development incompatible with flood function is not assessable without flood function mapping, which is what has been missing.

The mapping sorts the floodplain by what each part does in a flood. BMT prepared it for two scenarios: the Defined Flood Event, which the report describes as the 1% AEP event under the long-term climate change scenario to 2100, including increased rainfall intensity and sea level rise assumptions. The second is the Probable Maximum Flood.

The consequences differ by category. Development in floodways can affect flood behaviour and should generally be avoided. In flood storage areas, Larger-scale filling in flood storage areas can also have cumulative long-term impacts on flood levels and needs to be carefully considered. Flood fringe areas are those which are within the flood extent but outside floodways and flood storage areas, and are less sensitive to changes in flow or storage.

What an exhibition like this has drawn before

One number from the report sets expectations. The 2023 flood study itself went on exhibition between December 2024 and February 2025. Two submissions were received. They were reported to councillors via a bulletin, did not require any amendment to the study, and BMT finalised it in April 2025.

So the exhibition window is the hearing, and historically very few people have used it.

What councillors added to the officers' recommendation

Resolution 240926/19 carries five parts, and two of them were not about the studies themselves. Council resolved to include a training plan in the flood portal for the broader community, and to hold a separate information session for Alstonville and Wardell; and include consultation with Jali LALC and Cabbage Tree Island residents.

Cabbage Tree Island is the specific inclusion worth noting. The report records that the council has undertaken a number of flood studies and flood risk management plans for Ballina, Wardell and Cabbage Tree Island since the late 1990s.

A councillor left the room, and the reason is on the record

Before item 10.2, Cr Simon Chate declared an interest the minutes describe as significant, non pecuniary. The stated reason: Cr Chate lives in one of the houses impacted by the overland flood study. He left for the item, is recorded as absent and not voting on resolution 240926/19, and the minutes note he returned to the meeting at 12:27 pm. Cr Therese Crollick was absent from the meeting and did not vote on either resolution.

The liability framework behind all of it

One passage explains why councils follow the state manual closely. The report reproduces sections 733(1) and 733(4) of the Local Government Act, under which A council does not incur any liability in respect of flood advice or omissions made in good faith, and states that following the NSW Flood Risk Management Manual and Flood Prone Land Policy provides councils, statutory authorities, and state agencies and their staff, with indemnity for decisions they make and information they provide in accordance with the manual.

That is not a criticism. It does explain why the process is methodical and why the exhibition step is never skipped.

Sources

1. Ballina Shire Council, Minutes of the Ordinary Meeting, 24 September 2026 (PDF, 16 pages, downloaded and read 1 October 2026): resolutions 240926/19 and 240926/20 in full including all five parts of the first, the mover and seconder of each, the unanimous votes, Cr Crollick's absence, Cr Chate's declaration of a significant non-pecuniary interest and its stated reason, and his return to the meeting at 12:27 pm.
2. Ballina Shire Council, Agenda and business papers, Ordinary Meeting, 24 September 2026 (PDF, 109 pages, downloaded and read 1 October 2026): items 10.2 and 10.3, being the officers' reports on the Alstonville and Wardell overland flood studies and on the addendum covering flood function mapping. These are the source for the distinction between river and overland flooding, the March 2022 passage, the older-urban-areas passage, the 1% AEP standard for new development and the council's own correction of the one-in-100-years reading, the naming of Engeny and BMT, the statement that the 2023 study did not include flood function mapping and that such mapping is now required for development assessment, the statement that flood function mapping is required particularly in response to Clause 5.21 of the Ballina Local Environmental Plan 2012 and the report's description of what that clause emphasises, the Defined Flood Event and Probable Maximum Flood definitions, the floodway, flood storage and flood fringe descriptions, the December 2024 to February 2025 exhibition of the 2023 study and the two submissions it drew, the April 2025 finalisation, the note that the Lennox Head study is still being finalised, the reference to studies for Ballina, Wardell and Cabbage Tree Island since the late 1990s, and the sections 733(1) and 733(4) liability passages.

Live in Alstonville, Wardell or on the Ballina floodplain, or read the mapping differently? Tell us and we will check it against the council's own papers and log the outcome.