Otago Regional Council policy on dangerous dams

This policy will generally only impact you if you have a classifiable dam that either you or your recognised engineer believes to be dangerous, earthquake-prone or flood-prone.  

A dam is classifiable if:

• it has a height of 4 or more metres AND stores 20,000 or more cubic metres volume of water or other fluid; or
• it has a height of 1 or more metres AND stores 40,000 or more cubic metres volume of water or other fluid.

Many small farm dams and ponds will be excluded from the regulations as they are unlikely to exceed the height and volume thresholds above.  

Section 153 of the Building Act 2004 provides that a dam is ‘dangerous’ if it:

(a) is a dam classified as having a potential impact classification of medium or high; and

(b) is likely to fail -

1. in the ordinary course of events; or
2. in a moderate earthquake (as defined in the regulations); or
3. in a moderate flood (as defined in the regulations).

Section 153A of the Building Act 2004 includes the definitions for a ‘earthquake-prone’ or ‘flood-prone’ dam.

A dam is an earthquake-prone dam if the dam—

(a) is a high potential impact dam or a medium potential impact dam; and

(b) is likely to fail in an earthquake threshold event (as defined in the regulations).

 A dam is a flood-prone dam if the dam—

(a) is a high potential impact dam or a medium potential impact dam; and

(b) is likely to fail in a flood threshold event (as defined in the regulations).

Section 153 and 153A of the Building Act 2004 can be accessed at: https://www.legislation.govt.nz/act/public/2004/0072/latest/DLM307337.html

The definitions of a ‘moderate earthquake’, a ‘earthquake threshold event’, a ‘moderate flood’ and a ‘flood threshold event’ are provided in regulation 19 of the Building (Dam Safety) Regulations 2022

The policy must be read alongside the regulations which defines terms used in the Building Act in relation to dangerous, earthquake-prone and flood-prone dams.

The policy does not impact on your obligations under the regulations as a dam owner.

The policy sets out the ORC’s approach and priorities it will take in performing its functions in relation to dangerous, earthquake-prone and flood-prone dams in the Otago region.

For more information on the Dam Safety Regulations please find helpful resources here:

https://www.building.govt.nz/managing-buildings/dam-safety/resources

https://www.building.govt.nz/assets/Uploads/managing-buildings/building-safety/dam-safety-guidance.pdf   

Council has always had a policy on dangerous, earthquake prone and flood prone dams. Dam owners will continue to have the primary responsibility for identifying, monitoring, reviewing and reporting on dangerous, earthquake-prone and flood-prone dams and for reducing or removing the risk of harm to people, property and the environment.

The Building Act requires dam owners (with medium or high potential impact classification) to immediately notify the ORC if they have reasonable grounds to believe their dam is dangerous.

The Act (and Policy) places obligations on a recognised engineer (engaged by the owner to provide a certificate for the purposes of sections 135(1)(b), 142(1)(b) or 150(2)(f) of the Act) to notify the ORC and the dam owner if he or she believes that the dam is dangerous.  This must be done within 5 working days after the engineer forms their belief.

Unless the circumstances dictate otherwise, the ORC will seek to discuss options for action with the dam owner, with a view to obtaining from the owner a mutually acceptable proposal for reducing or removing the danger:

• The ORC may give written notice requiring the owner to carry out work on the dam, within a specified timeframe, to reduce or remove the danger.
• The ORC may direct and take action itself in certain circumstances, such as where there is immediate danger to the safety of persons, property, or the environment.
• For dams that are heritage dams, advice may be sought from Heritage New Zealand/Pouhere Taonga regarding any heritage values of the dam.
• The ORC will notify potentially affected communities downstream of a dangerous, earthquake-prone or flood-prone dams.  The Ministry of Business, Innovation, and Employment, the relevant Territorial Authority, Otago Civil Defence Emergency Management Group and Heritage New Zealand/ Pouhere Taonga may also be notified.

If you have any feedback or comments on the draft policy, please make a submission during the consultation period from 13 November – 15 December 2023.  You can decide at the time you lodge a submission whether you wish to speak to your submission at a hearing. Once the submissions have been collated, hearing dates and venues will be chosen. We are aiming to hold a number of hearings across the region depending on the number and locations of submitters. These will likely occur in late January – February 2024.  A hearing panel is yet to be determined but will consist of at least two elected Councillors. Once the hearings take place, the panel will deliberate and finalise the policy which will commence on 13 May 2024, the same day the Dam Safety Regulations take effect.

The regulations come into force on 13 May 2024.

You can email any questions on the draft Policy on Dangerous Dams, Earthquake-Prone and Flood-Prone Dams 2023 to damsafety@orc.govt.nz.

There is a useful resource already produced by the Ministry of Business, Innovation and Employment (MBIE) providing guidance on dam safety:

MBIE Dam Safety Guidance document https://www.building.govt.nz/assets/Uploads/managing-buildings/building-safety/dam-safety-guidance.pdf

A copy of the Building Act 2004 can be found here: https://www.legislation.govt.nz/act/public/2004/0072/latest/DLM306036.html