Managing Flood Risk in the Mullet Creek Catchment

The draft Mullet Creek Floodplain Risk Management Study and Plan was prepared with the cooperation, assistance, and support of many stakeholders, including community members and State Government representatives.

The draft Mullet Creek Floodplain Risk Management Study and Plan is an important milestone in the floodplain risk management process, that will allow appropriate flood risk management strategies to be put in place, such as development controls, emergency response measures, education and infrastructure solutions to benefit the community and businesses within the catchment. The report and associated flood data will be put onto the NSW Flood Data Portal so it can be publicly accessed, with the aim to provide a better understanding of flood behaviour, flood risk and wiser decision-making for the Mullet Creek catchment.

At its meeting on 8 May 2023, Council adopted the Mullet Creek Floodplain Risk Management Study and Plan. You can read the business paper and minutes for more information.

Thank you to everyone who contributed their time, thoughts and energy to help manage flood risk in this catchment.

We invited feedback on the draft FRMSP and received 67 submissions, including 15 via the online survey, four emails, one letter and 47 hard copy surveys. We had conversations with 20 attendees at the community information session and two representatives of an Aboriginal Traditional Custodian group. Two people submitted questions to the online Q&A and the project webpage had 633 unique views.

What we heard

Survey

Most of the feedback was provided via the survey (61 submissions). Nearly half of the respondents have lived, worked or visited in the catchment for more than 21 years. The most common response people said they would have to a major flood in the area, is to remain at their house. During a flood event, they would most commonly seek information via radio, social media and TV about road closures, predicted flood levels and evacuation notices. Respondents were asked to indicate their level of support for the options for managing flood risk in the Mullet Creek Catchment. Most were either strongly supportive or somewhat supportive of each option.

Respondents were also asked if they had other suggestions for managing flood risk in the catchment. Several made suggestions for stormwater infrastructure they believe would help, like bigger pipes, debris control structures, retention basins, levees and weirs. Some acknowledged the effectiveness of existing infrastructure and had observed improvements since mitigation measures were put in place.

There was a call for improvements to the maintenance of stormwater infrastructure and to increase the frequency of maintenance. There is a perception some drains are never cleared out and there is risk from blocked drains increasing flood impacts. Respondents identified specific areas of concern and made suggestions for maintaining stormwater infrastructure.

Some respondents called for improvements to creek and vegetation maintenance and identified areas of concern. People want maintenance to occur more frequently to remove rubbish and weeds, including lantana. Some believe dredging Mullet Creek will help.

Some respondents believe not allowing or limiting development on flood-affected land is needed, whereas others feel the current development controls are suitable. There is a perception new development contributes to worsening flood impacts. We heard more care needs to be taken when granting building permits, to ensure there is adequate drainage for all future development in flood-affected areas. Some believe there should be higher flood-mitigation requirements on developers.

Road raising was spoken about as a potential mitigation option. People made suggestions for roads they think should be raised and expressed concerns about roads being cut off in floods.

We received other suggestions, including:

• Educating the community about evacuation and driving through floodwaters
• Using Dapto High School as an emergency evacuation centre
• Installing flood warning signs and depth indicators on roads that are known flooding hotspots
• Purchasing flood-affected properties at real estate value, not market value.

Meeting with Aboriginal stakeholders

The Aboriginal Traditional Custodians we spoke to indicated there are sites and artefacts near the proposed locations of some of the recommended options. They requested to have a site officer present to monitor when the Enhanced Storage Areas go in. They would like to better understand the footprint of potential roadworks and requested archaeological testing take place if Council is looking to expand the footprint of roads near creeks.

Open submissions

We received open written submissions from:

• An operator of an electrical distribution network
• An engineering consultancy firm on behalf of an industrial landowner
• A development investment group on behalf of an industrial landowner.

Lengthy and/or technical submissions were provided in full to the team working on the FRMSP. The main points raised in these submissions included requests to:

• Clarify or add technical details
• Prioritise the Northcliffe Drive extension (EM9)
• Add other mitigation options to the Plan, including debris control structures and a levee

The representative of the electrical distribution network operator provided advice regarding their flood response plan and impacts of floods on the network.

Information session

Twenty people attended the information session at Dapto Ribbonwood Centre on 13 October 2022. Attendees provided comments on post-it notes and attached them to large maps showing the location of the preliminary options for emergency management and flood modification, as well as flood extents. People raised concerns about road closures and access during floods. People noted specific locations impacted by floods, in particular around Ena Avenue, and suggested ways to reduce flood impacts. They also noted their observations of flooding and flood impacts in these areas.

Social media

Commentary centred around people’s perceptions as to what causes flooding; allowing development and built-up areas on floodplains – and how it could be mitigated. Suggestions included raising a section of Bong Bong Rd and the bridge, raising the level of Darkes Rd and dredging the silt build-up at the mouth of the creeks.

Next steps

We will use this feedback to inform any required revisions to the draft Floodplain Risk Management Study and Plan. These are preliminary discussions about the recommended options. They will each require further investigation, consultation and approvals before going ahead. We will continue sharing information with the community and key stakeholders and seek input as we progress.

Read the full Engagement Report