Dam failure impact assessment
A dam failure impact assessment is a formal process that determines the risk to public safety if a dam were to fail.
All existing dams and proposed new dams require a failure impact assessment prior to construction, or after, if:
- they exceed specified height and storage volume criteria (see information below) and a failure impact assessment has not yet been accepted by the Department of Regional Development, Manufacturing and Water
- the previous failure impact assessment was accepted but the deadline to submit the next assessment has expired
- any proposed works to the dam will cause its storage capacity to increase by more than 10%. Note this may not apply to non-referable dams (those that do not meet size criteria)
- any proposed works to the dam would cause it to meet the height and storage volume criteria.
The Guideline for failure impact assessment of water dams (PDF, 2.2MB) describes whether a dam requires a failure impact assessment and, if so, the methods for assessment.
Height and storage volume criteria
Dams must have a failure impact assessment if they exceed the following height and storage volume:
- more than 10 metres high with a capacity of more than 1500 megalitres
- more than 10 metres high, with a capacity of more than 750 megalitres and a catchment area more than 3 times its maximum surface area at full supply level.
These size criteria are specified in the Water Supply (Safety and Reliability) Act 2008.
We have a process to identify dams across Queensland that may pose a risk to public safety but do not meet the size criteria triggers for automatic assessment.
Where we believe that a dam is referable, the dam owner will be issued a referable dam notice with supporting information.
If the dam owner disputes the referable dam notice, they will need to submit a failure impact assessment - certified by a registered professional engineer of Queensland - before the due date specified in the referable dam notice.
If a dam does meet the size criteria triggers for automatic assessment, the dam owner is responsible for undertaking a failure impact assessment. Once this is accepted, we will issue a notice of acceptance indicating when the next assessment is required:
- A failure impact assessment for a Category 1 referable dam will be at least 5 years after the acceptance of the assessment, but can be longer if we consider it appropriate
- Category 2 assessed referable dams will not require a further assessment
- For dams that do not meet the prescribed size criteria but have become referable under the referable dam notice process, the dam owner will be required to submit a further assessment by the date specified in their referable dam notice.