Chichester Dam risk assessment and upgrades
Community information sessions: Preparing for flood and dam safety events
The Dungog Local Emergency Management Committee, Hunter Water, NSW SES and NSW Police, will be providing Community Information Sessions to help property owners and residents prepare for a flood or dam safety event.
Letters of invitation are being sent to property owners downstream of Chichester Dam to Bandon Grove, and along the Chichester and Williams River down to Clarence Town.
The information presented will be customised for each location. Please RSVP if you would like to attend.
Community information session details
-
Bandon Grove - Wednesday 3 September
Property owners and residents between Chichester Dam and Bandon Grove are invited to attend one of two community information sessions at the Bandon Grove School of Arts:
Wednesday 3 September:
- Day: 12noon – 2pm, or
- Evening: 5pm to 7pm
*If property owners and residents between Chichester Dam and Bandon Grove are not able to attend one of these sessions, please contact our team on chichester.dam@hunterwater.com.au or call 1300 657 657 (during business hours).
-
Dungog - Wednesday 10 September
Property owners will soon receive an invitation to attend one of two community information sessions:
Wednesday 10 September:
Doug Walters Pavilion, 40 Mackay St, Dungog
- Day: 12noon – 2pm, or
- Evening: 5pm to 7pm
-
Clarence Town - 24 September
Property owners will soon receive an invitation to attend one of two community information sessions:
Wednesday 24 September:
Clarence Town Bowling Club, Corner Durham & Prince Sts, Clarence Town
- Day: 12noon – 2pm, or
- Evening: 5pm to 7pm
Fact sheets at community information sessions
Inspections and assessments
Hunter Water completes regular inspections of Chichester Dam, including:
- Daily visual inspections
- Inspections following an earthquake
- Intermediate (annual) inspections
- Satellite monitoring for any movement every two weeks
- Movement surveys every two years
- Comprehensive (five-yearly) inspections
- A five-yearly risk assessment
- A 15-yearly safety review
In 2023, we completed the five-yearly risk assessment and 15-yearly safety review. These assessments were finalised with input from an independent dam safety Expert Review Panel and submitted to the independent regulator, Dams Safety NSW in August 2023.
These assessment processes included using the latest engineering and scientific methods, some of which were not available for previous reviews. Because of this new technology, in 2023, for the first time, we were able to evaluate new risks and test for new scenarios.
The assessment report confirmed that Chichester Dam remains safe for day-to-day operations and continues to operate as it has for almost 100 years under normal conditions.
The risk assessment looked at how the dam could respond in a range of rare and extreme scenarios, such as extreme flooding and major earthquakes, which could lead to a dam failure. The main risk to the dam wall relates to very rare flooding. The cumulative result of the likelihood and consequence of all scenarios has been identified as being above the regulatory safety threshold determined under the Dams Safety Act 2015.
We are now planning and delivering upgrades for Chichester Dam to improve its long-term safety, especially during these rare and extreme events.
Chichester Dam Risk Assessment summary and full report
View the 2023 Chichester Dam Risk Assessment Summary and Report here.
Risk Assessment report recommendations and next steps
We are now implementing the report recommendations which include:
- upgrading concrete on spillway aprons as detailed in the report recommendations
- increasing flushing frequency of pressure relief drains and further enhanced monitoring
- installing additional modern monitoring equipment
- hydrologic (converting rainfall to runoff) and hydraulic (flow / movement of water) modelling
- site surveys and geotechnical investigations, including boreholes to collect and test soil samples.
We will continue to be proactive in the planning and delivery of safety upgrades for our dams and enhance our emergency response plans and ‘disaster readiness’ for all foreseeable hazards that may compromise the safety of the dam.
Work completed to date
Since the completion and public release of the Risk Assessment in 2023, the following has been completed:
Review flood hydrology and consequence assessment
An expert hydrology consultant was engaged in October 2023 to complete the update of these assessments. The initial detailed modelling has recently been completed with draft plans available for discussion at community sessions.
Environmental Assessments
Approvals have been received from National Parks and Wildlife Services for completion of geophysical investigations on the north abutment of the dam, along with preliminary discussions of proposed borehole drilling sites to be completed following this work. These approvals were necessary due to the sensitive environment surrounding the dam.
Closure of Knowledge Gaps
A consultant was engaged in November 2024 to undertake required investigations to close knowledge gaps in areas requiring specific technical expertise that will enable progression to the design of upgrade works, including photogrammetry, bathymetric and seismic surveys, geophysical testing, geological mapping, landslide geomorphological and reservoir rim stability hazard mapping. Due to the need to undertake assessments of the dam wall itself, significant work is being undertaken to plan the logistics of providing access for drilling of boreholes, with testing scheduled to be undertaken in early 2026. Due to the location of some of the boreholes, the water level in the dam may be required to be reduced to safely access the aprons below the spillway. This will be dependent on the dam level at the time of the investigations. If the water level needs to be lowered to allow the assessment to be safely undertaken, Hunter Water will notify downstream property owners of a controlled release.
Emergency Planning
A full update to the Chichester Dam Safety Emergency Plan was completed in December 2024, which also included the lowering of the Amber and Red alert levels to align with the outcomes of the Risk Assessment. The reduction in alert levels provides additional time for downstream residents to evacuate if required. A practical emergency exercise involving NSW SES, NSW Police and Dungog Shire Council was completed on 26 November 2024. An additional theoretical exercise was completed in June 2025 to further refine the plan and to provide training to additional Hunter Water staff members that can be called upon during emergencies. The emergency exercise was successful.
This revised Dam Safety Emergency Plan was used by all agencies in January, April and May 2025, in response to the severe weather events. SES notifications followed the protocols outlined in the Emergency Plan. The Dam Safety Emergency Plan is a comprehensive coordination document used by multiple agencies to ensure an appropriate response to severe weather and potential dam failure. While the document itself is not designed to be publicly facing, Hunter Water will talk through the Plan at the upcoming community information sessions, and we intend on sharing an executive summary version.
Instrumentation review
A review of options to provide close to real-time monitoring of the ancient landslide on the north abutment is due for completion in late 2025. Installation of any needed equipment would be installed during geotechnical investigations.
Emergency Lighting Upgrade
A major upgrade of the lighting of the dam wall was completed in June 2025 to improve the effectiveness of monitoring the dam during emergency events overnight or in poor light.
Post-tensioned anchor testing
Routine 5-yearly anchor testing is scheduled to be completed in late 2025 and may require a temporary reduction of the dam water level. If the water level needs to be lowered to allow the assessment to be safely undertaken, Hunter Water will notify downstream property owners of a controlled release.
Survey monitoring
Routine 2-yearly survey monitoring of the dam wall and north abutment is scheduled to be completed in late 2025.
Apron 4 Crack Repair
Design of cover plates to protect the historic crack in spillway been completed and contractor engaged. Work should be completed in late 2025 or early 2026 when spillway flows reduce.
Flushing of foundation pressure relief drains
Pressure relief drains were flushed in December 2023 and will be flushed again towards the end of 2025.
Learn more
We are here to help and answer any questions you may have about the report. Please get in touch by emailing yourvoice@hunterwater.com.au or calling 1300 657 657.
Frequently asked questions
-
What is Hunter Water doing to help downstream residents and businesses prepare for dam emergency situations?
We’re working closely with residents, businesses, and property owners located immediately downstream of Chichester Dam to ensure they understand the potential risks and know how they should respond in the event of a dam-related emergency.
The Dam Safety Emergency Plan (DSEP) outlines how we coordinate with emergency response agencies such as the NSW SES and NSW Police to help communicate important information to the community during a dam-related emergency. Please see our fact sheet – Dam Safety Emergency Plan for further details.
We recently completed an updated hydrology (flood), dam failure and consequence study, which provides property-specific information relating to dam failure scenarios. This information will be shared with property owners to support them in making their own emergency plans.
If you live or own property downstream of Chichester Dam – on the Chichester or Williams rivers, between the dam and Clarence Town – and are unsure how your property could be affected in a potential dam failure, please contact our Dam Safety Team on 1300 657 657 or email chichester.dam@hunterwater.com.au
-
How is a dam failure different to a flood event?
Chichester Dam is located on the Chichester River. When heavy rainfall occurs in the river’s catchment area, rainwater flows into the dam and spills over its spillway back into the river. This can cause the river level to rise significantly downstream over time, potentially leading to flooding downstream. This occurs progressively over time.
Dam safety alerts are issued based on how much water is spilling over the dam’s spillway. These alerts help inform residents of the rising flood risks, and the risk of a dam failure.
If the dam were to fail due to very rare flooding, additional water from the dam would rapidly surge down the already-flooded Chichester River. However, our dam safety planning recognises that evacuation alerts would have already been issued by this stage, as the triggers for evacuation are based on earlier flood indicators.
-
Is there always someone from Hunter Water at the Dam?
If a large rainfall event is forecast, staff are requested to stay onsite 24/7 in anticipation, even prior to the dam reaching the white alert level. During an emergency, a Hunter Water response team is activated with personnel onsite to monitor the dam, supported by a Dam Safety Engineer and a coordinator, who work 24/7 until the event is over.
Our systems control team routinely monitors all systems at the dam 24/7.
Hunter Water maintains two water level gauges at Chichester Dam that provide automated continuous monitoring of water levels, with backup power available. Automated high-water level alarms at the dam are triggered when the water flowing over the spillway reaches certain heights. These data and alerts are transmitted continuously over our secure network to staff both at the dam site and at Hunter Water’s Head Office in Newcastle to notify Hunter Water about potential emergency situations at the dam.
During normal day to day operations, employees are onsite during business hours (usually Monday – Sunday).
-
How can I be kept up to date with dam safety and the upgrade works at Chichester Dam?
If you’d like to receive non-emergency community updates about the Chichester Dam upgrades, register your details
Due to privacy legislation, Hunter Water does not have contact details of property owners or residents who are not Hunter Water customers. To ensure we can keep you informed, it’s important that you register your contact details and update them if your phone number, email, or postal address change. This helps us maintain an accurate contact list to keep you up to date.
-
How much will dam upgrades cost?
Hunter Water has commenced investigations and upgrade works at Chichester Dam, with $15 million allocated to initiate the initial dam safety projects between 2025 and 2030. This does not reflect all of Hunter Water’s proposed expenditure.
Significant additional upgrades will likely be required. The current investigations are confirming the scope, timeline and most cost-effective ways of undertaking these works.
-
Does Hunter Water control the volume of water that comes from the dam during a flood event?
No, Hunter Water cannot increase or decrease the total volume of water that flows out of the dam during a flood. Unlike some other dams, Chichester Dam does not have any gates installed on the dam’s spillway crest that would allow water to be stored above the full supply level to provide flood mitigation benefits.
When Chichester Dam is full, water flows out of the dam by flowing over the top of the spillway and into the Chichester River.
During flood conditions, Hunter Water will open the ‘scour’ pipeline in the base of the dam wall. The scour pipeline is operated during flooding events as part of good dam management, to flush silt from the base of the dam, which is deposited over time. When the scour is opened during a flood, it diverts only a small portion of the total flow that would otherwise go over the spillway; so, there is no change in the total flow volume that flows from the dam down the Chichester River.
As such, Hunter Water cannot limit or add to the volume water that flows down the Chichester River during a flood event. The volume of water flowing over the spillway reflects the natural flow volumes that would occur in the river if the dam were not present.
-
Why doesn’t Hunter Water release its Dam Safety Emergency Plan?
The Dam Safety Emergency Plan (DSEP) contains highly sensitive information, including detailed information about the dams’ design and construction, internal procedures and the names and contact details of key personnel.
We have assessed whether we could release the DSEP proactively under the NSW Government Information (Public Access) Act 2009, however, our assessment determined that releasing the full details in the DSEP could compromise its effectiveness during an emergency and/or compromise general safety and security at the dam.
-
I have another question not already answered here
Please email your question to the Dam Safety Team