Grange Planning Brain

title: Flood Overlay and Land Subject to Inundation Overlay Constraints council: golden-plains state: vic category: constraint classification: MAJOR status: in-progress last_compiled: 2026-05-30 source_docs:

  • Final Council Meeting Agenda 23.09.2025.pdf
  • Item 7.1 Attachments - Planning Scheme Amendment C104gpla - Teesdale Flood Study Panel Report.pdf
  • Item 7.1 Planning Scheme Amendment C104gpla Teesdale Flood Study 5.pdf
  • Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf
  • 8.4.1 - Authorisation of Planning Scheme Amendment C104 - Tessdale Flood Study.pdf
  • 8.4.2 - Authorisation of Planning Scheme Amendment C104 - Tessdale Flood Study-2.pdf

Flood Overlay and Land Subject to Inundation Overlay Constraints

Flood constraint planning in Golden Plains Shire is moving from a general municipal policy issue into a statutory map-control issue for Teesdale through Amendment C104gpla, which proposes changes to Floodway Overlay and Land Subject to Inundation Overlay mapping in the township. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.6) The practical planning effect is that land affected by the revised mapping would be assessed through flood hazard controls before subdivision, buildings, works, earthworks, or other development intensification can proceed. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.265)

Background

Golden Plains Shire’s planning scheme treats flooding as both a safety constraint and a land-use-management constraint. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.254) The scheme identifies flood-prone land across catchments of rivers and streams, with Inverleigh described as the township most affected by flooding because of the confluence of the Leigh and Barwon Rivers, and Woady Yaloak River identified as another key floodplain affecting the north of the Shire. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.254)

The Teesdale-specific statutory work arises from the Teesdale Flood Risk Identification Study, which Amendment C104gpla seeks to implement by amending maps for the Flood Overlay and Land Subject to Inundation Overlay in Teesdale. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.6) The study was funded through the Risk and Resilience Grants Program managed by Emergency Management Victoria, with Australian Government and Victorian Government funding under the National Partnership Agreement for Disaster Risk Reduction. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.6) Council’s September 2025 report states that the study incorporated model validation and consideration of climate change effects, was finalised in March 2023, and was adopted by Council in October 2023. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.6)

Analysis

Statutory Mechanism: From Flood Study to Permit Trigger

The mechanism is straightforward: the flood study identifies land subject to flood behaviour, Amendment C104gpla translates that technical mapping into the planning scheme maps, and the FO and LSIO then become statutory triggers for future permit assessment. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.6) In simple terms, the flood model is the measuring tape, the overlay map is the line drawn on the planning scheme, and the permit process is the gate that checks whether a proposed building, subdivision, fence, levee, or earthwork changes flood risk. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.265)

The Floodway Overlay is used for waterways, major floodpaths, drainage depressions, and high-hazard areas with the greatest risk and frequency of flooding. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.166) Its planning purpose is to maintain the free passage and temporary storage of floodwater, minimise flood damage, avoid incompatibility with flood hazard and local drainage conditions, reduce soil erosion and sedimentation, and protect water quality and waterway health. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.166)

The Land Subject to Inundation Overlay is used for flood-prone land in riverine or coastal areas affected by the 1 in 100 year flood, also expressed as the 1 per cent Annual Exceedance Probability flood, or for other land determined by the floodplain management authority. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.167) Its practical effect is broader than the FO because it captures inundation-prone land where development may not sit in the highest-velocity floodway but can still affect storage, access, building safety, and downstream flood behaviour. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.167)

Teesdale: Amendment C104gpla as the Active Constraint Change

Amendment C104gpla is the active statutory vehicle for Teesdale flood constraints. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.6) The amendment was exhibited between 6 February 2025 and 10 March 2025, with letters sent to relevant agencies and prescribed ministers and to 139 owners and occupiers of properties in Teesdale within the proposed FO and LSIO mapping changes. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.6) Exhibition also included public notice in the Golden Plains Times and publication in the Government Gazette. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.6)

The amendment attracted 18 submissions during exhibition, comprising three agency submissions and 15 resident submissions, and Council’s later report records that one additional submission was received after the April 2025 Council Meeting. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.6) The number of submissions matters because this is not a routine technical map correction; the amendment reached the threshold where contested land impacts required independent review by a Planning Panel. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.6)

The Panel hearing was held on 30 June and 1 July 2025, and the Panel Report was provided to Council on 31 July 2025. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.6) Council engaged Water Technology to provide expert evidence, the Corangamite Catchment Management Authority joined the Panel in support of the amendment, and four residents were parties to the Panel, with one resident calling flood expert evidence from Mark Colegate of Arcadis. (Source: Final Council Meeting Agenda 23.09.2025.pdf, pp.6-7)

The September 2025 council report states that the Panel found the basis for the amendment clear and well supported, found the flood study methodology and findings appropriate, and considered the study a suitable basis for the flood control mapping. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.7) The Panel recommended that Council adopt Amendment C104gpla as exhibited. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.7)

Development Assessment Consequences

The planning scheme policy for Golden Plains floodplain management applies to all land affected by the FO or LSIO. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.265) The local strategies are to direct buildings and works to land not subject to flooding, discourage subdivision that would increase risk to life and property from flooding, discourage earthworks that obstruct natural flow paths or drainage lines, and encourage open-type fencing such as post-and-wire fencing. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.265)

The planning mechanism therefore constrains both land use intensity and physical landform change. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.265) A subdivision can increase exposure by placing more households or buildings in a flood-prone area, while earthworks can move floodwater by blocking flow paths, reducing storage, or pushing water onto neighbouring land. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.265)

The existing Inverleigh FO1 schedule includes permit exemptions for limited works such as a domestic swimming pool or spa associated with one dwelling, certain repairs and routine maintenance, a rainwater tank not more than 50,000 litres, low pergolas or verandahs, sports grounds without grandstands or raised viewing areas, playgrounds and picnic shelters, bicycle pathways and trails where natural ground level is not increased, and upper-storey extensions within an existing building footprint where no new or altered onsite wastewater treatment system is required. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, pp.364-365) That schedule also requires a Flood Risk Report for applications under Clause 44.03. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.365)

The existing Inverleigh LSIO1 schedule includes permit exemptions for small non-habitable buildings under 50 square metres, extensions to non-habitable buildings where the total ground-floor area remains under 50 square metres, specified pergolas or verandahs, domestic swimming pools or spas associated with one dwelling, telecommunications facilities, upper-storey extensions within an existing footprint where no new or altered onsite wastewater system is required, rainwater tanks up to 50,000 litres, open-sided agricultural sheds, limited earthworks that do not raise ground level by more than 200 millimetres, specified repair and maintenance works, open sports grounds, playgrounds, protective walls or levee banks around existing dwellings protecting less than 200 square metres, accessway works that do not change finished surface level, and bicycle pathways or trails where natural ground level is not increased. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, pp.365-366)

The Teesdale amendment documents supplied in the manifest are too thin in extracted form to confirm whether Teesdale-specific FO or LSIO schedules create equivalent local exemptions, different application requirements, or different decision guidelines. (Source: Item 7.1 Attachments - Planning Scheme Amendment C104gpla - Teesdale Flood Study Panel Report.pdf) This is an analytical gap because the map change identifies where the control applies, but the schedule determines how strongly the control affects minor buildings, agricultural works, fencing, local earthworks, and repair activity. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, pp.364-366)

Climate Change and Risk Translation

Council’s September 2025 report states that the Teesdale study considered climate change effects and that the amendment adopts a climate change scenario to address environmental sustainability impacts. (Source: Final Council Meeting Agenda 23.09.2025.pdf, pp.6, 8) This matters because the overlay is not only recording historic flood behaviour; it is also embedding a forward-looking risk assumption into the statutory map base. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.8)

The wider planning scheme context says flood impacts are increasing because of land use and vegetation changes, with urban expansion, raised earthworks, and clearing for rural and urban development contributing to increased flooding instances. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.254) This creates a cause-and-effect chain: land use change can alter runoff and storage, altered flood behaviour can increase risk to people and property, and overlay controls then become the planning scheme’s method for limiting further intensification in locations where the flood model identifies exposure. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, pp.254, 265)

Contest and Evidence Weighting

The contest around C104gpla appears to have focused on whether the flood study and resulting mapping were technically justified, because the September 2025 report records Panel findings that the methodology and study findings were appropriate and a suitable basis for flood control mapping. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.7) The presence of CCMA in support, Water Technology as Council’s expert, and Arcadis evidence for one resident shows that the dispute was technical as well as property-specific. (Source: Final Council Meeting Agenda 23.09.2025.pdf, pp.6-7)

The supplied extracted Panel attachment does not expose the Panel’s detailed reasoning, issue-by-issue findings, submitter arguments, or any recommended wording changes. (Source: Item 7.1 Attachments - Planning Scheme Amendment C104gpla - Teesdale Flood Study Panel Report.pdf) As a result, this page can identify the procedural path and the reported Panel conclusion, but it cannot independently test which flood modelling assumptions were challenged, what sensitivity tests were discussed, or whether any individual properties were considered marginal inclusions or exclusions. (Source: Item 7.1 Attachments - Planning Scheme Amendment C104gpla - Teesdale Flood Study Panel Report.pdf)

Relationship to Settlement and Growth Planning

Flood constraints interact with settlement planning because the scheme discourages intensification of land use and development in floodplains and seeks future use and development of flood-prone land to minimise inundation consequences for life and property. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.254) This means flood mapping can affect whether land is suitable for additional dwellings, subdivision, expanded township development, or works that alter flood storage. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, pp.254, 265)

The Planning Scheme Review records implementation of the Teesdale Structure Plan as a recent strategic planning action and also records Teesdale as a significant township in the Shire’s permit activity profile. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, pp.12, 16) The Teesdale flood amendment therefore sits alongside township structure planning rather than outside it, because flood overlays help define which parts of a settlement can absorb change without increasing exposure to flood hazard. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.6)

Current Status

As at the 23 September 2025 council agenda, officers recommended that Council receive the Panel Report, adopt Amendment C104gpla as exhibited, and request the Minister for Planning to approve the amendment under section 31 of the Planning and Environment Act 1987. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.6) The report states that Council was required under section 27(1) of the Planning and Environment Act 1987 to consider the Panel’s report before deciding whether to adopt the amendment. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.7) The next statutory step identified in the report was submission of the adopted amendment to the Minister for Planning for approval. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.7)

Dependencies

  • Blocks: The amendment blocks reliance on outdated Teesdale flood mapping by replacing the existing map base with study-informed FO and LSIO mapping. (Source: Final Council Meeting Agenda 23.09.2025.pdf, pp.6, 8)
  • Blocked by: Final statutory effect is blocked until Council adopts the amendment and the Minister for Planning approves it. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.7)
  • Informed by: The amendment is informed by the Teesdale Flood Risk Identification Study, the Corangamite Regional Floodplain Management Strategy, Australian Rainfall and Runoff guidance, and Victoria’s Climate Science Report 2024. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.8)
  • Implements: The amendment implements the Teesdale Flood Risk Identification Study by changing FO and LSIO maps for Teesdale. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.6)
  • Conflicts with: The source material does not identify a formal policy conflict, but the 18 exhibition submissions and one later submission show affected residents contested aspects of the amendment. (Source: Final Council Meeting Agenda 23.09.2025.pdf, p.6)

The Corangamite Catchment Management Authority is a key cross-jurisdictional actor because it joined the C104gpla Panel in support of the amendment and is the relevant floodplain-management authority context for the Shire’s floodplain policy documents. (Source: Final Council Meeting Agenda 23.09.2025.pdf, pp.6, 8) The Planning Scheme Review also records that Inverleigh FO and LSIO mapping was identified through mapping undertaken by the Corangamite Catchment Management Authority. (Source: Att 7.6.1 - Golden-Plains-Planning-Scheme-Review-2022_FINAL combined_3.pdf, p.376)

Gaps in This Analysis

The supplied extracted text for the September 2025 Panel Report attachment contains page labels but not the Panel Report’s substantive text, so this page cannot analyse the Panel’s detailed treatment of submissions, expert evidence, model assumptions, or property-specific mapping disputes. (Source: Item 7.1 Attachments - Planning Scheme Amendment C104gpla - Teesdale Flood Study Panel Report.pdf) The supplied extracted text for the April 2025 amendment attachment also contains page labels but not the substantive amendment package, so this page cannot confirm the exact map sheets, ordinance wording, schedule drafting, explanatory report, or instruction sheet content from that attachment. (Source: Item 7.1 Planning Scheme Amendment C104gpla Teesdale Flood Study 5.pdf)

The supplied extracted text for the October 2023 authorisation attachments is also extraction-thin and does not expose the Teesdale study maps, model outputs, affected-property tables, or authorisation briefing detail. (Source: 8.4.1 - Authorisation of Planning Scheme Amendment C104 - Tessdale Flood Study.pdf) The companion October 2023 attachment is likewise extraction-thin and cannot be used to quantify affected land area, number of properties added to or removed from FO or LSIO, flood depths, velocity categories, or climate-change sensitivity. (Source: 8.4.2 - Authorisation of Planning Scheme Amendment C104 - Tessdale Flood Study-2.pdf)

The highest-priority corpus gap is the full machine-readable Teesdale Flood Risk Identification Study and the full OCR text of the C104gpla Panel Report, because without them the analysis cannot quantify mapped flood extent, depth, velocity, hazard category, property count, or the number of lots where future subdivision or buildings would be materially constrained. (Source: Final Council Meeting Agenda 23.09.2025.pdf, pp.6-8)

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