Regulations requiring dams and reservoirs over a certain size to be classified for their risk are likely to prove an expensive surprise for farmers in coming months.
After over a decade of to-ing and fro-ing over what will be included and how to include it, Ministry of Business, Innovation and Employment’s dam safety regulations will come into effect on May 13 next year. They are likely to capture 3000 water storage bodies nationally, of which it is estimated as many as 900 may be on farms and properties for stock water and irrigation storage purposes.
Irrigation New Zealand technical adviser Stephen McNally said the water bodies captured under the dam regulations extend beyond dams themselves to include the likes of irrigation ponds and even irrigation canals.
“There are two thresholds for the water bodies it captures. One is a body of water contained within a 1m high wall and totalling 40,000cubic metres or more, and the other is water held within a 4m high wall, and totalling 20,000cubic metres or more.”
Dam owners will have only three months after May 13 2024 to determine if their water body is captured by the regulations, and to register with local authorities.
“These are often large structures that no one has always paid much attention to in the past and it applies retrospectively. It could include that dam your grandfather shaped with his bulldozer back in the 1970s.”
Working with MBIE, Irrigation NZ has developed a dam “ready reckoner” to help farmers quickly and cheaply determine if they have a qualifying structure on their property.
If it qualifies, the structure’s risk level must be assessed, requiring a certified engineer to determine its “low”, “medium” or “high” potential impact category (PIC).
The dam’s PIC is determined by not only its construction, but also the downstream consequences of any failure of the structure, and include community, environmental and even cultural impacts.
McNally said at this point New Zealand landowners are likely to experience a significant bottleneck, with only nine certified senior dam engineers operating in the country at present.
“With 3000 sites out there, that is a massive workload. The implications are that you are not going to do that between now and July next year.”
In its submission on the dam regulations, Federated Farmers expressed concern over the need for low PIC dams to be submitted to a registered engineer for audit and approval.
Its estimates were that in 2019 the cost of submitting even a low-PIC dam for a certificate was $3000-$7000. Comprehensive assessments, likely required for high-risk dams, are put as much as $50,000-plus.
McNally said those high-risk structures may also face ongoing costs for annual safety audits that could also run into the thousands of dollars.
“We have had some dam owners say to us they are simply going to decommission their dams and drain them rather than face that cost.”
Both Irrigation NZ and Federated Farmers have highlighted the irony of the regulations’ impact on water storage given the government’s desire to store more water as a climate change response.
Feds has suggested integrated farm plans could be a better means of capturing low-PIC dams, and a random sampling of low-PIC dams could ensure that remains a valid way to capture them.
Irrigation NZ CEO Vanessa Winning said more time is needed to get the regulations right, and tools to improve adherence and understanding require an easy check sheet to comply as part of existing farm plan processes.
In June a soil dam administered by Waipa District Council on the edge of Hamilton burst, sending 23,000 cubic metres of water through 20 homes in the suburb of Glenview, in the city’s south.
That came despite a decade’s worth of analysis and warnings of its flaws and warnings of imminent failure.
The majority of major known failures have tended to come from larger scale projects, including the Ophua dam failure during construction in 1997, and the Ruahihi power project canal failure in September 1981, a day after then prime minister Robert Muldoon opened it.
Some farm dams were compromised by the Kaikoura earthquake in 2016, requiring drainage of some structures in the Seddon district under emergency orders.
Both Irrigation NZ and Feds have stressed that their concerns relate primarily to the “low” PIC structure costs, rather than the regulations in general.
“We are just trying to get a bit of pragmatism around the regulations, and to assist farmers on understanding what they may be up for, and what they can do for themselves,” McNally said.