The below petition is for Camden Council from Elderslie residents to formally raise our collective concerns in response to the draft Narellan Creek Flood Study including Detailed Overland Flow, soon to be on public exhibition.

Our properties have now been classified as flood-affected due to the PMF (Probable Maximum Flood) event, despite the fact that our street/s have not experienced any flooding in any of the major weather events in recent years - including some of the worst floods in Camden’s recorded history including but not limited to:

1. March 2021 – Widespread East Coast Flooding

• Camden was impacted by a major flood event described by the NSW Premier as a "one-in-100-year event."

2. July 2022 – Nepean River Flooding

• The Nepean River experienced significant flooding, affecting Camden and surrounding areas.

3. March 2022 – Severe Weather and Flooding

• Heavy rainfall led to flooding in parts of Camden, contributing to one of the wettest periods on record for the region.

4. July 2021 – Surface and Sewer Flooding

• Camden experienced significant surface and sewer flooding, marking one of the most notable flood events in the past 40 years

The above were significant flooding events, where neighbouring suburbs were severely impacted, yet our streets remained unaffected.

Additionally, we would like to remind Council that two prior, publicly endorsed flood studies – the Nepean River Floodplain Risk Management Study (2022) and the Upper South Creek Flood Study – did not classify our street as flood-affected, even when considering severe weather and overland flow events. Given the lack of flooding during real-world flood events, no significant change in topography or drainage, and the absence of street-level justification, this sudden change in designation based solely on PMF modelling is both unwarranted and damaging.

We believe his new classification in the 2025 Draft Narellan Creek Flood Study should be seriously questioned for the following reasons:

1. Consistent Findings in Prior Studies

Both the Nepean River Floodplain Risk Management Study (2022) and the Upper South Creek Flood Study were professionally conducted using contemporary tools, historical rainfall, and terrain data. These studies concluded no flood affectation for our streets – including from mainstream riverine and overland flood events.

Why this matters: If previous comprehensive modelling, rainfall analysis, and catchment behaviour assessments showed no significant flood risk, it calls into question why the current study – using similar or only marginally updated data – suddenly reclassifies the area.

2. Empirical Evidence Has Not Changed

Despite multiple severe weather events and "1-in-100-year" floods between 2020 and 2022, our streets remained flood-free — not just from riverine sources (Nepean) but also from overland flow and stormwater. This real-world evidence supports the conclusions of the earlier studies and contradicts the assumptions of the 2025 model.

Why this matters: Flood modelling must be grounded in observable behaviour. If actual flood events — particularly recent, extreme ones — have not resulted in flooding, then changing classifications based on hypothetical models without supporting historical evidence

3. Absence of Infrastructure Changes to Warrant New Flood Paths

The Draft 2025 Study cites “improved drainage infrastructure data” as part of the model update. However, no major alterations or known degradations in drainage infrastructure on or near our street have occurred since the last studies.

Why this matters: If neither terrain nor infrastructure has significantly changed, the drainage and flow assumptions in the older studies should still hold true. Arbitrary or unexplained model output that deviates from past consistent findings should be critically reviewed.

4. Over-reliance on PMF Modelling

The current study classifies properties as affected under the PMF (Probable Maximum Flood) event — the most extreme and rare hypothetical flood possible, typically with no historical precedent.

Why this matters:

• PMF is not used for development controls — even the Council's own letter admits this.
• Insurers and valuers may still treat this as a serious flag, causing financial harm to homeowners.
• Earlier studies focused on realistic and historically validated events (e.g., 1% AEP or 1-in-100-year floods), and did not find our street at risk even under those conditions.

5. No Community-Specific Explanation Provided

There has been no clarification from Council on what specifically has changed in the model or landscape to justify reclassifying our street.

Why this matters:

• A sweeping reclassification without street-level explanation is not transparent.
• Council has a responsibility to provide specific, evidence-based justifications for new flood-risk declarations — especially when they contradict earlier publicly funded studies.

In Summary - Key Concerns:

1. Inaccuracy and Overreach of Classification
   The reclassification appears to be theoretical rather than evidence-based. There is no historical precedent or observed overland flow data supporting flood affectation on our streets. This raises serious questions about the methodology used and its real-world accuracy.
2. Negative Impact on Insurance Premiums
   The designation of a property as “flood affected” is known to cause substantial increases in insurance premiums, even when no flooding has ever occurred. This creates undue financial burden for property owners and is based on a scenario that has never materialised in this location.
3. Reduction in Property Values
   Labelling a home as flood-prone can significantly lower its market value. Buyers may be deterred, financing may become more difficult, and resale prospects are likely to be diminished — all due to an arguably flawed theoretical model.
4. Lack of Consultation or Justification Specific to Our Street
   The community was not adequately consulted before this designation was proposed, and the public exhibition does not compensate for the lack of direct engagement. We request transparency regarding the criteria used to classify our street and an opportunity for site-specific reassessment.
5. Inconsistency with Historical Data and Lived Experience
   Given the frequency and intensity of recent flood events in the region, the complete absence of flooding on our streets should be a critical consideration in any current or future flood mapping and planning decisions.

Our Request:

We respectfully but firmly urge Council to:

• Reassess the flood classification of our street based on actual historical flooding evidence.
• Provide a clear, detailed explanation of how overland flow modelling has resulted in the proposed classification.
• Undertake on-site inspections or surveys if required to validate or refute modelled predictions.
• Commit to further consultation with directly affected residents before any designation becomes final.
• Consider the long-term financial and emotional impact this classification will have on law-abiding, rate-paying residents.