Tsunami sirens will be disabled along the Coromandel Peninsula coast by the end of summer 2022.
Thames-Coromandel District Council did not meet national compliance for 19 sirens on the peninsula operated by Fire and Emergency NZ.
The standard requires national consistency for public alerting of a tsunami.
Civil Defence Emergency Management controller Garry Towler said all sirens, including nine in Thames-Coromandel settlements, will be disconnected by February 2022, with an assurance that 85 per cent of people on the Coromandel will be alerted in another way.
"The sirens in the Coromandel have an effective alert coverage and reach to the peak population of 40 per cent or less and [are] deemed a poor, confusing and inefficient way of alerting people of a tsunami, as there are different siren sounds for each one that aren't consistent with the national standard," he said.
"Our council had initial discussions with FENZ (Fire and Emergency NZ) on the progressive withdrawal of the tsunami siren paging system from its 20 sirens.
"We will ensure that before any siren is disconnected, at least 85 per cent of the population will be able to receive all or part of the suite of options and is working with all parties to make that happen by February 2022."
The national cellphone alert, Red Cross and GNS apps, fibre and broadband, media and social media platforms, backed up with public education will be used to warn of an impending tsunami.
Currently, the national cell alert rollout reaches 70 per cent of the national population.
Mr Towler says the Government's ongoing rural broadband rollout and additional towers will reach further into less populated areas and see coverage improve.
"The Red Cross app can now be regionally activated which allows for localised alert messaging, the fibre rollout continues as well. Everyone can access this app online for free."
The council is unable to give any accurate figures on the percentage of people in the district who receive the national cell alert, saying data collected went only to a Waikato region level.
Risks associated with shutting down tsunami sirens were discussed at a meeting of the Waikato CDEM Group Joint Committee on August 21.
The Coordinating Executive Group (CEG) took professional advice, which highlighted the risk to communities where removing sirens would leave a void with no other alerting systems.
It said TCDC, with support from GEMO, should provide an implementation plan for alternatives to the current siren system, with reasonable time scales and a managed withdrawal of FENZ sirens.
"Acknowledgement of the criticality of communication and education with affected communities, in planning to withdraw sirens" was also key.
TCDC says it is working with individual communities to develop their own community response plan.
However in Tairua this month, residents in one of the most at-risk communities directed questions to Civil Defence emergency management asking if there was a Tairua Emergency Response Plan and where it would be available to the Tairua Community.
Tairua Residents and Ratepayers Association chairwoman Jean McCann says many older residents do not use smartphones and she was concerned they would not even get to hear about proposed changes to the alerting system.
Questions to council included: 'What is the plan for the many older residents, some of whom don't have cellphones and internet?' And, 'what are the Emergency Signals?'.
Mr Towler said an extensive public education campaign would include new tsunami and alerting signs at all main beaches and highways to inform people of the options they will have to be notified of an emergency.
The council is also still investigating the viability of an indoor alerting device, a plug-in device that relies on FM radio signals to alert residents. A decision to proceed or not will be made before the end of this year.
The product has been developed by IAD Technologies NZ Ltd, formerly Tsunado Ltd, which holds intellectual property rights.
Around 94 residents have trialled the device since 2016 to see if existing FM broadcast stations are strong enough to activate it in homes.
The trials cost ratepayers $120,000 for consultants, who reported the device gave 80 per cent coverage on the Coromandel Peninsula. But in a report to the council at its May 12 meeting, councillors heard the consultant's report could not be relied on to give adequate information to make a decision.
Councillor Sally Christie, who represents TCDC on the Waikato CDEM meetings, said the council was trying to extend the timeframe with FENZ on the sirens.
"We're working with FENZ at the moment because that's not ideal for us and we're trying to extend that while we increase other options.
"Anyone that says it's easy or that money is going to solve it, it isn't true. It involves all of us playing a part."
Christie says the Coromandel was challenged geographically with coverage, and with the mix of permanent and absentee ratepayers.
"It is about the high tech solutions and about that really grassroots response to everyone knowing their neighbourhood and knowing who has got a cellphone and who doesn't, and if you have to stop and pick up Mrs X.
"The reality is the council and fire brigades will do their best but we may not be there."