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
• or
• 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.

Assessment process

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.

Also consider...

• Read the flood mitigation studies and dam reviews.
• Read the guidelines for hazardous waste dams (i.e. for regulated structures). Contact the regulator, the Department of Environment and Science for further information.