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Flood safety

Development in flood prone areas

We have special provisions for development in flood prone areas to reduce the risks to buildings, residents and neighbours. These include:

The Port Stephens Local Environment Plan 2013 (Section 7.3) outlines the provisions for development in Flood Prone Areas in Port Stephens and includes reference to the Flood Planning Map.

Development Control Plan (DCP)

The development controls applied to a flood prone lot are dependent on the flood hazard category and the nature of flooding on the subject property. Flood related development controls are detailed in the 2014 DCP (section B5).

The current Floodplain Risk Management Policy was adopted in March 2016 and aims to:

  • Take an integrated risk management approach to the development of flood prone land, recognising that land should not be unnecessarily restricted and that decisions take into account the flood hazard.
  • Provide a framework to manage floodplain risk through cost effective measures that address the flood hazard as identified in local floodplain risk management studies and plans.
  • Ensure that the Emergency Services are provided with the most up to date flood information so they can include it in their emergency response and recovery planning.

Flood certificates

A flood certificate provides the flood planning level for a particular lot (the minimum finished floor level for a new development on the lot). If available, the flood certificate may also provide the highest flood hazard category for the lot, the surveyed floor level to the residence and the highest flood level that could conceivably occur at the site (the probable maximum flood level).

To check whether a particular lot is flood prone please refer to the Flood Certificate Application to complete a “Land Check”. If the lot is flood prone a Flood Certificate may provide more detailed information.

Online flooding certificate

Use this online form to apply for a flood certificate or check if a particular lot is flood prone.

The flood information has been compiled from information provided by external consultants and flood studies completed by Council in accordance with the NSW Floodplain Development Manual.

A flood certificate provides an estimate of real flood characteristics. Any particular flood may be different to the conditions that were assumed to determine the information described in the certificate. The information has not been independently verified or checked beyond the agreed scope of work and Council does not accept liability in connection with unverified information.

Council acknowledges that its flood information may be incomplete and varying in accuracy, however it is the best information available to Council at the time of issue. The advice is subject to change if more accurate flood data becomes available to Council. Accordingly the information in the Certificate is not warranted after the day of issue.

Council is not responsible for updating flood information when site conditions have changed from the time of the original flood study and does not accept responsibility arising from any change in site conditions.

A flood certificate may be useful for you if you are developing or redeveloping on a particular lot, if you are considering purchasing a lot or if you wish to be informed about the flood risks on a lot.

Council charges a fee for the provision of flood certificates. Council's current fees are:

Standard Requests

  • $265 for a single lot flood certificate
  • $205 per lot for multiple adjoining lots flood certificates

Urgent Requests

  • $530 for a single lot flood certificate
  • $410 per lot for multiple adjoining lots flood certificates

Following Councils receipt of the flood certificate request form and full payment of the applicable fees a standard request flood certificate(s) will be provided via email within ten (10) working days.

Urgent requests attract a higher fee and will be processed and emailed within three (3) working days.

Anyone can apply for a flood certificate

Each Flood Certificate is custom-made for the particular lot in question as the amount of flooding varies. The Flood Certificate shows the latest flood information that Council possesses and the amount of information may vary for different areas and lots.

Floodplain Advisory Panel

The Floodplain Advisory Panel helps Council to development and implement flood studies, floodplain risk management studies and plans undertaken in Port Stephens.

Since 2016, the panel has been providing advice to Council to assist the Floodplain Risk Management Process. The Panel is not a formal committee of Council and does not have a formal role in decision making, policy direction or delegating additional work to be carried out by Council.

The Floodplain Advisory Panel consists of:

  • Core members — Council staff, Councilors, community members and representatives from Office of Environment and Heritage, Hunter Water Corporation, State Emergency Services
  • Local representatives — catchment specific community representatives and consultant representatives.

The Floodplain Advisory Panel meets twice a year with additional meetings called when required.

Terms of Reference

View the terms of reference for the Floodplain Advisory Panel (PDF 100KB).

Floodplain Management Program

Council continuously works on updating and improving our understanding of flood risk within the Port Stephens area using the NSW government's Floodplain Management Program.

Floodplain Management Process:

There are 5 stages in the Floodplain Management Process:

  1. Data Collection - collecting relevant information
  2. Flood Study – build a hydraulic model to define the nature and extent of the flood problem in technical rather than map form
  3. Floodplain Risk Management Study – update the hydraulic model to determine options in consideration of risk
  4. Floodplain Risk Management Plan – planned actions to be adopted for Council
  5. Plan Implementation – doing the works.

Port Stephens flood studies and plans:

Information on the flood studies, drainage studies and floodplain risk management studies and plans that have been undertaken in the Port Stephens area can be accessed below. Further information, including flood models, data and Report Appendices, is available by registering and logging on to the State Government's SES Flood Portal.

Williamtown Salt Ash Floodplain Risk Management Study and Plan - 2017

Williamtown Salt Ash Flood Study Climate Change Review - 2012

Williamtown Salt Ash Flood Study -  2005

Hydrologic Soil Mapping

Hydrologic soil maps describe the infiltration rates for different soil groups across Port Stephens. These maps can be used to evaluate land for planning, development and stormwater management.

Council's Development Control Plan (DCP) requires that stormwater drainage plans and a written description of the proposed drainage system be prepared in accordance with the current Australian Rainfall and Runoff Guidelines using the current hydrologic soil mapping data for Port Stephens.

This map provides an estimation of hydrologic groups of soils according to the four class system and was released by the NSW Government on 11 October 2016. It uses the best available soils mapping coverage and was derived by linking a Hydrologic Group class to a particular Great Soil Group.

Group A soils have high infiltration rates, even when thoroughly wetted consist primarily of deep well drained sands or gravel. These soils have a high rate of water transmission.

For design purposes, it is assumed that the Antecedent Moisture Condition is "rather wet" (refer to Australian Rainfall and Runoff (ARR) 2016, Table 5.3.11) and the Horton Maximum (Initial) Infiltration Rate is 83.6 mm/hr, the Minimum (Final) Infiltration Rate is 25 mm/hr and the Shape Factor/Decay Rate k is 2 /hour (refer ARR 2016, Table 5.3.12).

Group B soils have moderate infiltration rates when thoroughly wetted and consisting primarily of deep coarse textures. These soils have a moderate rathe of water transissions.

For design purposes, it is assumed that the Antecedent Moisture Condition is "Rather wet" (refer to ARR 2016, Table 5.3.11) and the Horton Maximum (Initial) Infiltration Rate is 66.3 mm/hr, the Minimum (Final) Infiltration Rate is 13 mm/hr and the Shape Factor/Decay Rate k is 2 /hour (refer ARR 2016, Table 5.3.12)

Group C  soils have slow infiltration rates when thoroughly wetted and consisting of primarily of soils with a layer that impedes downward movement of water, or soils with a moderately find texture. These soils have a slow rate of transmission.

For design purposes, it is assumed that the Antecedent Moisture Condition is "Rather wet" (refer to ARR 2016, Table 5.3.11) and the Horton Maximum (Initial) Infiltration Rate is 33.7 mm/hr, the Minimum (Final) Infiltration Rate is 6 mm/hr and the Shape Factor/Decay Rate k is 2 /hour (refer ARR 2016, Table 5.3.12).

Group D soils have very slow infiltration rates when thoroughly wetted and consisting primarily of clay soils with a high swelling potential, soils with a high water table, soils with a clay layer, and shallow soils over nearly impenetrable materials. These soils have a very slow rate of transmission.

For stormwater design purposes, it is assumed that the Antecedent Moisture Condition is "Rather wet" (refer to ARR 2016, Table 5.3.11) and the Horton Maximum (Initial) Infiltration Rate is 33.7 mm/hr, the Minimum (Final) Infiltration Rate is 6 mm/hr and the Shape Factor/Decay Rate k is 2 /hour (refer ARR 2016, Table 5.3.12).

View the Hydrologic Soil Mapping via the links below.

Council do not object to a development proponent wishing to undertake geotechnical testing to determine site specific permeability. Given the potential for large variability in test results and their impact on design and performance outcomes, Council require a development proponent to follow a detailed approach.

For additional Infiltration Information, please view our fact sheet: