Dam Safety

Dangerous dams

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).

Earthquake-prone dams

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).

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.

Flood-prone dams

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 on the New Zealand Legislation website.

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 Regional Council's approach and priorities it will take in performing its functions in relation to dangerous, earthquake-prone and flood-prone dams in the Hawke’s Bay region.

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

Dam safety resources

The regulations come into force on 13 May 2024.

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 HBRC 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 HBRC 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, HBRC 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:

• HBRC may give written notice requiring the owner to carry out work on the dam, within a specified timeframe, to reduce or remove the danger.

• HBRC 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.

• HBRC will notify potentially affected communities downstream of a dangerous, earthquake-prone or flood-prone dams.  The Ministry of Business, Innovation, and Employment, relevant territorial authorities, relevant iwi authorities, Hawke’s Bay Civil Defence and Emergency Management Group and Heritage New Zealand/ Pouhere Taonga may also be notified.

• You can email any questions on the proposed Policy on dangerous dams, earthquake-prone dams and flood-prone dams 2024 to damsafety@hbrc.govt.nz

• The Ministry of Business, Innovation and Employment (MBIE) has resources and guidance on dam safety available on the Building Performance website.

• View a copy of the Building Act 2004 on the New Zealand Legislation website.