A pamphlet drop warning of the potential impact of a dam collapse on Tasman town has been labelled "mischievous" and "misleading".
Brightwater residents found leaflets in their letterboxes claiming an eight metre tidal wave from the proposed Waimea Dam could swamp their homes and the local school.
"I've had older people scared witless," says Nelson MP Nick Smith. "I think it's dirty and sneaky to be scaring the bejesus out of people".
Two thousand leaflets were distributed anonymously around Brightwater, warning of a potential collapse of the proposed Waimea Dam in the event of an earthquake.
"My concern is that it is anonymous and so the person is hiding behind that with these sorts of scary claims," says Dr Smith.
The author fronted up today in an interview with 1 NEWS and says he’s not hiding his identity.
"If you put your name there, the first thing they want to do is attack the messenger rather than receive the message," Richmond resident Maxwell Clark explained.
But the message is under fire, with the Tasman District Council and dam designers Tonkin and Taylor describing the flyer’s information as "quoted out of context and misinterpreted".
Earthquake risk
The leaflet highlights the location of the dam in relation to the Waimea-Flaxmore and Alpine Faults. At its closest, the Waimea-Flaxmore fault system passes within about eight to nine kilometres northwest from the dam site.
But Tasman Mayor Richard Kempthorne says the dam is designed to withstand a one in 10,000 year earthquake, "so that even in a catastrophic event, in an earthquake of this nature, it will not structurally fail".
Inundation
The flyer includes a map taken from a Tonkin & Taylor emergency action plan, as part of its hazard assessment, "in the unlikely case of a rapid dam break".
"Such studies are hypothetical in nature, and entirely divorced from the remote chances of a dam failure ever occurring," says Tonkin & Taylor’s Doug Johnson.
The map relates to the flow of water from the dam into the Brightwater area, not the height, as the flyer suggests.
"What we would expect, if there is a catastrophic failure, is the height of the river at the Waimea bridge would be four metres and the height of the town going through houses would be between 50 and 100 centimetres," says Mayor Kempthorne.
That still concerns Maxwell Clark, who says he’s worried about the potential risk to the public with the speed of which the water could move. He claimed in the flyer that the township would be "completely inundated with floodwater" within 20 minutes, with little notice to evacuate.
Tonkin & Taylor says that estimate is wrong as the "elapsed time for the peak water level to occur is 61 minutes, not 20 minutes. While normally unmanned, the dam will be fully instrumented and constantly monitored to detect any unusual occurrences and potential emergency situations and enable actions to be taken to reduce the risk of a dam break".
Property values
The flyer also asked Brightwater households to consider whether their properties would be saleable or insurable after the dam was built.
"Tasman District Council has the right to register the potential inundation risk onto each individual property title," it stated.
The council rejects that suggestion, telling 1 NEWS any changes would require a "credible hazard, which there is not".
Division
The proposed Waimea Dam is the council’s preferred option to solve a water supply issue in the region.
It’s caused division in the community, with tensions expected to rise ahead of a final vote of the dam this Friday.
As an intensive care paramedic, Maxwell Clark says he continues to hold “grave concerns” for the public’s safety, despite assurances from the council and dam experts.
“I'm not challenging the engineers' ability to perform, what I'm saying is nature is more powerful than engineers,” he explains.
Mayor Kempthorne says “wouldn't have a bar” of the Waimea Dam plans “if I didn't think it was going to be safe for people living in Brightwater and even for people living up the Lee Valley.
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