Dams - Construction, Alterations and Safety Regulations

Construction or Alterations of Large Dams 

If you are an owner of a large dam or canal, or you're planning to construct, modify or remove a dam, canal or structure associated with a dam, you'll need to consider whether you need a building consent before you begin work.
 
‘Large dam’ means 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 as set out in the Building Act 2004.  If it is not a large dam it doesn’t require a building consent but it must be constructed to meet the Building Code.

If you are an owner of an existing dam, you have until 13 May 2024 to prepare for your dam safety responsibilities under the new Building (Dam Safety) Regulations which are requirements to ensure dams are maintained and inspected after being built. For more information refer to the Building (Dam Safety) Regulations 2022 section below. 
 
Potentially there are two types of consents that may be required to build /alter a large dam which are resource consents and/or building consent. It is possible, depending upon the size of the proposed dam and its location, that it may require only one of the above, possibly both of the above or even none of the above. 
 
For information on resource consents please email our Consents team on consents.enquiries@horizons.govt.nz or call our Horizons Duty Planner on Freephone 0508 800 800. Alternatively you can find more information here. 
 
Horizons is responsible for dam activities within the Region, and our Team Leader District Advice is available to assist with building consent applications and dam safety regulations. For more information on this service, please see our dams factsheet below.

Dangerous Dams Policy

The Building Act 2004 introduced legislation for managing the safety of existing and new dams in New Zealand. Under this Act, regional councils must have a policy on how they will deal with dangerous dams, earthquake-prone dams and flood-prone dams in their region. 

The Manawatū-Whanganui Region has a number of large dams that are used for a variety of purposes including hydroelectric generation, water supply, flood control, irrigation, farm stock supply and recreation. This policy was developed to help reduce the risk of dam failure in Manawatū-Whanganui Region.

 

Dam owners have the primary responsibility for identifying, monitoring 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 in a timely and effective manner.

 

An engineer engaged (by the owner) will notify the Council and the owner of the dam if he or she or they believe that the dam is dangerous.

 

The policy was reviewed to ensure it aligned with the new dam safety regulations. The revised policy was adopted by Council on 28 May 2024.  
 
You can view a copy of the Dangerous Dams Policy here.
 

Building (Dam Safety) Regulations 2022

As expected the Ministry of Business and Employment announced new regulations around dam safety. The regulations have commenced from 13 May 2024, requiring the first step in the regulatory process to be completed by 13 August 2024.

The regulations aim to protect people, property and the environment from the potential impacts of dam failures and set a minimum requirement for dam safety. They also promote regular monitoring and surveillance practices, as dam owners will be responsible for maintaining them to acceptable safety levels.

Detailed information and resources to support dam owners, technical practitioners and regional authorities with their responsibilities are available on MBIE’s website.

MBIE have produced a helpful dam safety guidance document which Horizons District Advice highly recommend you read.

Dam safety frequently asked questions are available on Waikato Regional Council's website.

The editable Dam Classification Certificate can be accessed from Waikato Regional Council's website. If you own a classifiable dam, this certificate must be certified by a recognised engineer and submitted to Horizons Regional Council by 13 August 2024.

To find the list of recognised engineers please visit Engineering New Zealand's website.

Immediate steps for dam owners to take:

Step 1
If you are the owner of a water retention structure, you need to determine if your structure meets the definition of a dam. See the definition of a dam in the Building Act 2004.

If yes, go to step 2.
If no, no further action is required under these regulations.
 
Step 2
Determine if you have a classifiable dam (that is, if it meets the height and volume threshold shown above). Find out how to measure and calculate your dam.
 
If you have a classifiable dam, go to step 3.
If you do not have a classifiable dam, no further action is required under these regulations.
 
Step 3
Determine your dam’s potential impact classification (PIC). Find out about how to determine a dam’s PIC. Go to step 4.
 
Step 4
Have the PIC audited and certified by a Recognised Engineer. A list of Recognised Engineers can be found here.
This needs to be completed on a Dam Classification Certificate. The editable Dam Classification Certificate which can be accessed from Waikato Regional Council website. Go to step 5.
 
Step 5
Submit your dam’s classification certificate to the Horizons Regional Council District Advice team at dam.safety@horizons.govt.nz  by 13 August 2024.  There are administrative charges associated with the dam safety regulations.  The dam safety fees are listed in Horizons Long Term Plan under Annual Administrative Charges. The fixed minimum charge for each dam classification certificate is $200 (including GST). This will be invoiced to the payee once the certificate is received by Horizons.
 
In addition to these steps, owners of dams with a medium or high PIC have further actions they need to take. There are also lodgement fees for the additional steps required for medium or high PIC dams. 
 
The only additional requirement for owners of dams with a low PIC is to review their dam’s PIC within five years of the regional authority approving it. This fee is the same as the initial dam classification certificate lodgement fee.

Dam Safety Regulations - Dam Size

Please note that the classifiable dam size is the same as the “large dam” criteria for building consents. 
*On 28 March 2024 the Government has agreed to raise the height threshold of the dam safety regulations from one metre to four metres. You can read more about this announcement here. 

Questions and Enquiries

If you have any dam related questions, contact our District Advice team via our online enquiry form or email dam.safety@horizons.govt.nz

Tips for completing the online form:

• Search by property address or valuation number (e.g. 11 Victoria Avenue or 12345 678 00). 
• Exclude the town/city in the search field as the database searches by district.
• For rural addresses without road numbers, enter the property by valuation number (remember to tick the valuation number box on the form).
• Find property details and valuation numbers via the District Advice map in our online map gallery. Search for the property by street address, title, or valuation number, or navigate the map manually. You can also find property information via our online Rates Search tool.
• If you need help submitting the form, please email us at dam.safety@horizons.govt.nz.