A view looking upstream on the Ngaruroro River towards the gorge and cableway at Whanawhana. The dam would be built on a tributary of the river. Photo / Warren Buckland
A view looking upstream on the Ngaruroro River towards the gorge and cableway at Whanawhana. The dam would be built on a tributary of the river. Photo / Warren Buckland
A proposed dam being led by Hawke’s Bay Regional Council on a tributary of the Ngāruroro River would have a wall 58 metres high.
Councillor Xan Harding revealed more details of the proposed Whanawhana dam at the first meeting of the farming group Heretaunga Sustainable Water on Thursday.
The WaimeaDam in Tasman, at 53m high, has a capacity to hold 13 million cubic metres of water and is the largest public dam built in New Zealand in the past 30 years.
But the amount it can hold would be less than half the capacity of the proposed dam in Whanawhana, if it is to go ahead.
Both would still be dwarfed by the proposed Makaroro River dam in Central Hawke’s Bay, which would have a capacity of 93 million cubic metres.
Harding walked the group of 300 farmers and growers at the Havelock North Function Centre through previously unpublished details about the project, using a set of slides marked “in confidence”.
He showed slides with a photo of the location of the Whanawhana valley that the dam would flood, and also an aerial image.
Based on the two images, Hawke’s Bay Today has concluded the dam – which has had its exact location kept closely under wraps – is likely to be placed downstream on the Otamauri Stream, before it goes underneath the Whanawhana Rd bridge and feeds into the larger Ngāruroro River.
Slides showing the location of a new dam in Whanawhana. Photos / Heretaunga Sustainable Water
Slides showing the location of a new dam in Whanawhana. Photos / Heretaunga Sustainable Water
The council announced in March that it would share the cost of a feasibility study for the 27 million cubic metre project.
The cost of the study will be about $3.2 million and will be shared by Hawke’s Bay Regional Council (HBRC) and central Government, supported by a 2020 loan from the Provincial Growth Fund. The spend is budgeted for in HBRC’s long-term plan.
It is HBRC’s latest attempt to provide water security in the region after it abandoned the failed Ruataniwha Dam project in Central Hawke’s Bay in 2018 after $20m was spent on pre-development.
Harding said the proposed dam would have no impact on a Water Conservation Order on the upper Ngāruroro River because it would be built on a tributary.
The 27 million cubic metres of water annually would be divided up – with 17 million used to fill the catchment and 10 million available to harvest from the Ngāruroro River.
Harding said there had been no “fatal flaws” identified in the dam at present, although he said it may not reliably fill each year.
He said an ideal model for control of the dam would be to place it in the joint hands of the Napier City Council, Hastings District Council, mana whenua and Heretaunga water users, and its viability would depend on who was willing to pay what for the water.
“Regional council wants to get the hell out as soon as possible ... we’ve seen that model not work in the region before and we don’t want it again.”
