Dam Safety Requirements

Once your dam is constructed and you are in the post-construction phase of your dam’s life, you need to ensure that you continue to monitor, maintain and repair your dam to ensure the integrity of the dam is retained and the potential for failure remains low.

You will need to determine if your dam meets the definition of classifiable within the Building Act 2004 and ensure you comply with the Legislative requirements relating to dam safety.

A dam owner under the Building Act 2004 is recognised as the person who legally owns the physical dam itself. The dam owner won’t always be the landowner, though this is the most common type of ownership. Some dam owners are a party or person who benefits from the dam and has a vested interest in the dam. There may be record of this situation within resource consents or building consents, but this is not always the case.

As a dam owner it is their legal responsibility to ensure the safe management of their dam and that the requirements of the regulations are met. It is the owner’s responsibility to:

• Determine if their water retention structure is a dam
• Determine if it meets the definition of a Classifiable Dam
• Complete Dam classification, Dam Safety Assurance Programme (if required) and Annual Dam Compliance Certificates, within the required timeframes
• Engage with relevant parties or bodies that may be affected by dam failure
• Have Dam classification, Dam Safety Assurance Programme (if required) and Annual Dam Compliance Certificates, audited and certified by a Recognised Engineer
• Provide the required Form’s to the Regional Authority within the required timeframes
• Notify the Regional Authority if their dam is found to be Dangerous
• Notify the Regional Authority of ownership change.

The level of risk (refer to Potential Impact Classification) determines the level of responsibility and management required by the owner.

More information on roles and responsibilities can be found below.

The Building Act 2004 requires that all regional authorities carry out Dam Safety functions, duties and powers. Currently, each regional authority holds its own Dam Safety functions, duties and powers. 

The regional authority is required to:

• Administer and monitor dam safety regulations:
  • Establishing and manage a register of dams in its region
  • Approve or refuse Dam Classifications (Form 1)
  • Approve or refuse Dam Safety Assurance Programmes (Form 2)
  • Receiving the Annual Dam Compliance Certificates (Form 3)
• Adopt and implement a policy on dangerous dams, flood-prone dams and earthquake-prone dams
• Compliance and enforcement of the regulation requirements to ensure compliance with the requirements
• Take action, when necessary, if any dam, large or small, poses an immediate danger to the safety of persons, property or the environment.

More information on roles and responsibilities can be found below.

A classifiable dam is:

A dam that has a height of 4 or more metres and stores 20,000 or more cubic metres volume of water or other fluid.

This is as defined in the Building (Dam Safety) Regulations 2022 and as per the interpretation within the Building Act 2004.

If your dam meets the definition, the Regulations require the dam owner to classify the Potential Impact of a failure of the dam, have this classification certified by a Recognised Engineer and provide this to the Regional Authority.

More information on dam safety requirements can be found below.

The requirement to determine if your dam meets the definition of a Classifiable Dam is for all dams and regardless of if your dam had a Building Consent or was constructed prior to 1991, when a Building Consent became a requirement.  If your dam meets the definition, then it must be Classified.

If you have a dam that has been constructed without a Building Consent that meets the definition of a Classifiable Dam, we recommend you contact your local Regional Authority to discuss this issue further. 

As per section 151 of Building Act 2004, each Regional Authority must establish and maintain a register of dams in its Region.  As of 2024, Council’s have established a register of classifiable dams. This is information that has been verified through the Potential Impact Classification process and means that the information is valid.  

Please contact us if you have any queries.

A Potential Impact Classification (PIC) in accordance with the Building (Dam Safety) Regulations 2022, is a risk classification that identifies the potential impact a dam’s failure could have on the community, historical and cultural places, critical or major infrastructure and the natural environment.

A classified dam must be given one of the following classification levels:

• Low potential impact
• Medium potential impact
• High potential impact

The method of classification is detailed in 9 Method of classification of the Regulations. A PIC assessment can be undertaken by anyone but must be audited and certified by a Recognised Engineer.

The owner must provide the PIC to the Regional Authority within 3 months of the dam being commissioned. If you have an existing dam that you believe is classifiable and has been commissioned for longer than 3 months, please contact your Regional Authority to discuss this further. You are likely currently non-complying with the Regulations and will need to take action quickly.

The PIC will determine what further management is required for your dam. Medium and High PIC dams are required to undertake Dam Safety Assurance Programmes and Annual Dam Compliance Certificates.

Dam classifications must be reviewed within 5 years of the first approval or last review. The classification will also need to be reviewed when works that requires building consent is carried out on the dam and that work results, or could result, in a change to the potential impact of a failure.

It is the owners responsibility to ensure that the PIC is completed, audit and certified by a Recognised Engineer and submitted to the Authority within the required timeframes.

More information on PIC can be found below.

A Dam Safety Assurance Programme (DSAP) is a structured framework of plans and procedures that plan and complete activities requires for the safe operation and management of the dam.

For the Building (Dam Safety) Regulations 2022 all dams with a Medium or High PIC are required to have and submit a DSAP for their dam.

DSAP’s can be prepared by anyone and must be made up of the requirements within the Regulations sections 11 to 18. The DSAP must be audited and certified by a Recognised Engineer.

The timing of the first DSAP being provided is based on the PIC level. For a High PIC the DSAP must be provided no later than 1 year after the date of the PIC approval. For a Medium PIC, it is due 2 years after the date of the PIC approval.

Review of DSAP’s are required. For a High PIC it must be reviewed:

• Within 5 years of the approval of the initial DSAP
• After the first review, at not more than 5 year intervals.

For a Medium PIC it must be reviewed:

• Within 10 years of the approval of the initial DSAP
• After the first review, at not more than 7 year intervals.

The DSAP should also be reviewed at any time when building work requiring a Building Consent is carried out on the dam and the works results, or could result, in a change to the PIC.

More information on DSAP can be found below.

An Annual Dam Compliance Certificate (ADCC) is an audit of evidence and confirmation that compliance with the DSAP has been achieved in a 12 month period. The ADCC is only required for dams with DSAP’s and must be audited and certified by a Recognised Engineer.

This certificate must be provided annually on the anniversary date of the DSAP approval.

More information on ADCC can be found below.

In the first instance you will need to work with the Recognised Engineer. Understanding the reasons they are unable to certify the documentation will go a long way in solving this miscommunication. Remember a Recognised Engineer has been deemed qualified and competent to audit the dam safety documentation and if they are not willing to certify your PIC, DSAP or ADCC there will be a reason.

Should an owner fail to comply with the regulations, it is likely it will be an offence under the Building Act 2004 and can lead to infringement or enforcement which carried fines of anywhere up to $150,000.

Non-compliance is costly and time consuming. If you are struggling to make compliance or are suffering current hard ship, please contact your Regional Authority as soon as possible so that we can work with you in ensuring your dam ends up complying with the Regulations.

More information on non-compliance and infringements can be found below.

As Classifiable Dams are Large Dam’s under the Building Act, any building work including decommissioning or demolition of a dam is likely to require a Building Consent prior to any work being undertaken.

In terms of draining or dewatering a dam, there is also likely consenting requirements under the Resource Management Act.

Any plans to demolish or dewater a dam should involve a discussion with your Regional Authority in the first instance to ensure you have all the correct approvals in place to enable the works.

A Dangerous Dam is defined within the Building Act 2004 and the Building (Dam Safety) Regulations 2022. A Dangerous Dam is a dam that:

• Has been classified as a high or medium potential impact dam
• Is likely to fail –
  • In the ordinary course of events; or
  • In a moderate earthquake (defined by the regulations); or
  • In a moderate flood (as defined by the regulations).

For a High PIC dam, a moderate earthquake is one that results in ground shaking at the site of the dam at an intensity with an AEP of 1 in 100 but not less than the 1 in 100 AEP shaking determined using a seismic hazard factor of 0.10 (Z factor). And a moderate flood is a flood that would result in water or other fluid flowing into the reservoir formed by the dam at a flow rate with an AEP of 1 in 100.

For a Medium PIC dam, a moderate earthquake is one that results in ground shaking at the site of the dam at an intensity with an AEP of 1 in 50 but not less than the 1 in 50 AEP determined using a seismic hazard factor of 0.10 (Z factor). And a moderate flood is a flood that would result in water or other fluid flowing into the reservoir formed by the dam at a flow rate with an AEP of 1 in 50.

If you or your engineer has reasonable grounds to believe that your dam is, or has become, dangerous under the Building Act 2004 you must immediately notify the regional authority in whose region the dam is situated.

Your Recognised Engineer who is auditing the dam classification also has a responsibility to notify both the Regional Authority and Owner if the dam is Dangerous. They must do this within 5 working days of forming a belief that the dam is dangerous.

Please contact your Regional Authority if you believe your dam meets the definition of dangerous under the Building Act.

If you or your Recognised Engineer deem your dam earthquake or flood prone, get in touch with your local Regional Authority. They will help guide you through their Dangerous Dam policy requirements for these prone dams.

Where the Regional Authority believes that your dam may be an immediate danger to the safety of persons, property or the environment they will class this dam as an immediate danger.  An immediate danger can be used on any dam that meets the definition of a dam under the Building Act 2004.

The Chief Executive of the Regional Authority can issue a warrant to take action, when necessary, to remove that danger. Having a dam classed as an immediate danger can lead to council intervening in rectifying the dam to remove the immediate danger and the owner of the dam being liable for the costs of the action. Council can recover these costs, and this may become a charge on the land.

If you have any queries about an immediate danger dam, please contact your local Regional Authority.