Dams – building consents and safety regulations
Below you will find information for building, modifying and removing a dam, as well as the new requirements for dam owners under the Building (Dam Safety) Regulations 2022.
Do I need a building consent for my dam?
Under the Building Act 2004 all “large” dams require a building consent from a regional council.
Under the Building Act, a large dam is defined as follows:
"a dam that has a height of 4 or more metres and holds 20,000 or more cubic metres volume of water or other fluid."
The height of a dam is the vertical distance from the crest of the dam, and must be measured-
"(a) in the case of a dam across a stream - to the natural bed of the stream at the lowest downstream outside limit of the dam; and
(b) in the case of a dam that is not across a stream - to the lowest elevation at the outside limit of the dam; and
(c) in the case of a canal - to the invert of the canal".
The crest of a dam is defined to mean the uppermost surface of the dam, not taking into account any camber allowed for settlement, or any curbs, parapets, guard rails, or other structures that are not part of the water-retaining structure; and for the avoidance of doubt, any freeboard is to be considered as part of the water-retaining structure.
Applying for a dam building consent
All North Island regional councils, except Auckland Council, have transferred its powers to process all building consent applications for dams to the Waikato Regional Council. The Waikato Regional Council will also undertake the inspections required during the construction phase and issue the final code of compliance certificate once the dam has been completed.
Information about the requirements for building and maintaining dams and the relevant application forms are available to download directly from the Waikato Regional Council website.
Northland Regional Council and other regional councils are required under the Building Act to maintain a register of large dams for their respective regions.
The register enables councils to contact large dam owners on matters of importance to them, such as new regulations and guidance material on dam safety. If you own a dam, then you should check with us whether your dam should be on the register.
To register your dam, or for general enquiries regarding dams, please contact the council's Consents team.
Dam safety regulations
The government has introduced new dam safety regulations to protect people, property, and the environment from the potential impacts of a dam failure.
The regulations commence on 13 May 2024.
Purpose of the regulations
The aim of the regulations is to ensure that dams over a certain height or storage capacity are:
- well operated and maintained
- regularly monitored.
The regulations provide a consistent, nationwide framework by setting out minimum safety standards for dams in New Zealand.
Owners of classifiable dams (those impacted by the regulations), who have limited or no dam safety procedures in place, will need to become familiar with their responsibilities under the Building Act 2004 and the regulations, and with the actions they must take, and by when. Owners of dams classified as low potential impact will have few responsibilities. Most small dams will not be impacted by the regulations.
Dams affected by the regulations
The regulation applies to ‘classifiable’ dams, which are dams that:
- have a height of four or more metres and store 20,000 or more cubic metres of water or other fluid
- have a height of one or more metres and store 40,000 or more cubic metres of water or other fluid.
How to comply with the regulations
All owners of a classifiable dam must undertake the following:
- Submit the potential risk classification (PIC) of their dam to council.
- Review the dams PIC every 5 years.
Owners of a dam with a PIC of medium or high must undertake these additional requirements:
- Submit a dam safety assurance programme (DSAP) to council.
- Undertake a dam safety review.
- Submit an annual compliance certificate.
- Review the DSAP every 5-10 years.
Implementation and timeframes
The timeframes vary depending on a dam's potential impact classification (PIC). Dams must be classified as either low, medium, or high potential impact, depending on the impact of the dam’s failure.
Recognised engineers also have responsibilities under the regulations. Engineering New Zealand Te Ao Rangahau, as the Registration Authority for Chartered Professional Engineers, is responsible for assessing and registering recognised engineers. Together with the New Zealand Society on Large Dams (NZSOLD), they have developed the framework and registration process for recognised engineer qualifications and competencies to be assessed.
Resources to support dam owners
Building performance has developed resources to help dam owners become familiar with what is required and to prepare for the commencement of the regulations in 2024.
The resources include online learning modules, guidance documents and templates with information to supply the regional council.
Still need help?
If you require further assistance, please reach out to dam safety team here at Northland Regional Council – [email protected]