Council’s dam safety plans shared with residents, businesses.
Published on 13 November 2025
Over the past year, Waitaki District Council has been developing a Dam Safety Assurance Programme to ensure it meets the requirements of the Building (Dam Safety) Regulations Act 2022, which came into effect in May 2024.
Under new regulations, all owners of classifiable dams in New Zealand had to submit assurance programmes to their regional council by 14 August 2025 if modelling shows that failure of dams would have a high impact on people and infrastructure.
Oamaru’s Ardgowan Dam requires an assurance programme under the regulations. Begun in 1877, the Ardgowan Dam was completed in 1884 and stores around 160,000m3 of water that supplies more than 16,000 consumers from Oamaru south to Moeraki with drinking water.
Council’s Director for Natural and Built Environment, Roger Cook, said considerable work has been undertaken to ensure the dam complies with the regulatory requirements.
“Developing the Dam Safety Assurance Programme is a rigorous process which seeks to identify and manage any risks to a dam’s structure, the impacts a dam failure might have, and what should be done in the event of a potential or actual dam failure incident”.
Council engaged dam specialists Tonkin & Taylor to produce a hydrology and engineering report. These were used as the basis for developing the safety assurance program, which includes operational procedures and emergency action plans for dealing with potential emergency events, such as severe flooding or a significant earthquake.
Mr Cook said Ardgowan Dam had stood up to multiple events since it was constructed nearly 150 years ago to supply drinking water to Oamaru residents, and recent engineering reports showed that it is still structurally sound.
“While the dam and risk of failure haven’t changed materially over the past 140 years, the legislative requirements and our knowledge about the causes and consequences of dam failure have improved, which is a good thing in terms of better understanding how to keep our community safe”.
“Even the best dams can fail under extreme circumstances, and the consequences can be catastrophic for communities in the same way a natural disaster can be, so having a Dam Safety Assurance Programme in place provides comprehensive way of managing risk through a mix of monitoring, operational actions and improvements, and planning for emergency events - including working with emergency services to evacuate people in the flood path in the unlikely event that the dam did fail.”
“Our management of the Ardgowan Dam means it is safer now than before. The regulations have changed, the dam itself has not. We now have preventative and precautionary actions we can take to avoid issues – and a plan in place should the very unlikely event of failure occur”
Meetings with residents and businesses who could be potentially impacted took place on the 11, 12 and 13 November, and information is available on Council’s website now, at this link: Ardgowan Dam | Waitaki District Council
ENDS
media@waitaki.govt.nz