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Batemans Bay creek study identifies flooding risk

Eurobodalla Council has commissioned a technical study into the flooding behaviour of seven urban creek catchments in the greater Batemans Bay region.

Currently on public exhibition for community feedback, the draft Batemans Bay Urban Creeks Flood Study details the flooding risk of Maloneys Lagoon at Maloneys Beach, Long Beach Lagoon at Long Beach, Surfside Creek at Surfside, the Batemans Bay Water Garden, Hanging Rock Creek at Catalina, Joes Creek at Batehaven and Short Beach Creek at Sunshine Bay/Caseys Beach.

Residents – particularly in these areas – are being urged to take a look at the study and provide their feedback to Council. A drop-in session will be held Thursday 17 June, from 12.30pm to 6.30pm, at the Hanging Rock Function Centre, where Council staff and the consultants who prepared the study can answer any questions. No RSVP is required.

Council’s flood planning officer Cameron Whiting said the study focused on flooding from rainfall events while taking into account projected sea-level rise impacts.

“This draft study is the first step in better understanding where there may be a flooding risk, giving Council the information needed to progress the next steps of the process, which is to look at mitigation options,” he said.

“It also helps other agencies, like State Emergency Service, plan for the potential impacts of flooding on the community.”

Councils are required by law to prepare for and manage the risk of flooding, as set out in the NSW Government’s NSW Flood Prone Land Policy and Floodplain Development Manual 2005.

The draft Batemans Bay Urban Creeks Flood Study, prepared by Rhelm environmental consultants, was jointly funded by a NSW Government floodplain management grant and Council.

It is available to view at until 4.30pm on Wednesday 30 June.

Above: McLeods Creek that sits adjacent to the $70 million Bay Pavillions and the proposed 30m tower development on the old Batemans Bay Bowling Club site was not one of seven catchments examined as part of Eurobodalla Council’s draft Batemans Bay Urban Creeks Flood Study. Lindsay Usher, Director of Planning and Sustainability Services responded on this very same question, writing to a local Surfside resident in April 2021 saying: "The Study aims to identify flood risk in the Batemans Bay area as raised over time by the

community. The Study will inform future land use, infrastructure and emergency

management planning." The flood risk associated with McLeods Creek is not sufficient to warrant inclusion in the

Study area for the following reasons:

• Mcleods Creek drains to the Clyde Estuary and is permanently open. This reduces the

potential flood extent associated with McLeods Creek.

• Development adjacent to McLeods Creek is low density and typically high relief,

therefore there is limited potential for the area to be impacted by flooding.

• Inundation of the CBD is unlikely to occur from the western side, as the highway

forms a barrier to flood waters. Available flood modelling of the Bateman’s Bay CBD

undertaken on behalf of the NSW Government confirms this, indicating that in a 1%

AEP event, the highway would only be minimally overtopped and this is confined to a

very small area of the CBD.

Source NOTE: Council advise: 1.1.1 Mackay Park, like the rest of the Batemans Bay town centre, is low lying and a recently completed coastal hazard study has found that the majority of the site is projected to be inundated by a 1% storm event within the period to 2100. For future development on the site to exceed the 1% event, floor levels should be at or above 2.74m Australian Height Datum (AHD). To exceed the 5% event for the 2100 planning period, floor levels should be at or above 2.61m AHD [1].

[1] The current code is to be superseded following the completion of the Open Coast CMP in mid-late 2022. The Geo Technical investigation for the new Bay Pavillions site revealed the presence of groundwater table at relatively shallow depths of just 0.8m AHD (1.5m below the surface at 2.2m AHD) with a high probability of occurrence of acid sulfate soils (ASS), between 1m and 3m below existing ground levels. With such a body of water and with such a shallow groundwater basin located directly adjacent to a multi million complex it is surprising that the Batemans Bay Urban Creeks Flood Study did not include McLeods Creek in Council's brief, especially given the ongoing questions around the unknown impacts of the new bridge pylons nearby and their influence on flood water discharge.