It’s part of a four-pronged regional water security programme, supported by the Provincial Growth Fund, which includes a region-wide freshwater assessment, a 3D aquifer mapping project, and exploring viable locations for small-scale community storage schemes in the Central Hawke’s Bay (Tukituki River) and Heretaunga (Ngaruroro River) catchments.
Council acting manager regional water security Tom Skerman says the regional water assessment is analysing water supply and demand across the region to 2050.
That includes looking at predicted future changes, such as predicted urban growth and the higher water needs of crops under climate change projections.
Skerman says in the past work looked at increasing water supply options but it is now also focused on managing demand, including more efficient water use, water conservation and water reuse, along with what can and cannot be achieved under the current allocation system.
It’s hoped the assessment will be complete by this time next year.
In parallel with the assessment, the council is investigating solutions to achieve a more secure water supply, including water storage.
“We know storage is a viable and well-proven tool,” Skerman says.
The idea is that once the assessment is completed potential storage sites will have already been assessed and identified, so public discussion about future water use and security can be well-informed.
The council has allocated $5 million to the water security programme through its current long-term plan and the Provincial Growth Fund has effectively matched that for the development and analysis of solutions.
The PGF has also earmarked a further $23m for the building of storage solutions that survive full feasibility studies.
Skerman says one of the PGF’s criteria is that it is not interested in “mega” storage projects.
No hard rule has been specified in terms of size of a single storage project but a figure of 20 million cubic metres of water has been floated.
The unsuccessful Ruataniwha dam proposal would have held up to 90m cubic metres.
A report presented to the council last month predicts the region’s annual GDP will fall by up to $120 million a year by the middle of the century if nothing is done about water security.
Hawke’s Bay hill country farmer Sam Robinson, who was involved in promoting the Ruataniwha project, supports any plan to improve water storage capabilities in the region and is pleased the council is looking at future options.
He says the biggest challenge of building small dams in the area, which was discovered doing due diligence on the proposed Ruataniwha dam, is the geotechnical problems that need to be overcome.
Initially, the Ruataniwha proposal aimed to have four or five medium-sized dams, capable of holding between 12-20m cubic metres of water, on separate tributaries.
The problem was that much of Central Hawke’s Bay’s Tukituki catchment is alluvial gravel-based soil subject to liquefaction during earthquakes, so is unsuitable to build water storage schemes on.
Robinson says backers of the Ruataniwha dam found the only location would stand up to that scrutiny was its proposed site on the upper Makaroro River, although he is not advocating for that dam to be revisited.
He does not believe small, on-farm dams are the long-term solution to the region’s wider future freshwater needs.
Not only are they considerably more expensive to build than larger scale community projects, estimated at three to six times more expensive to build on a per cubic metre basis once consent, design and earthworks are taken into account, they also inundate what was once productive land.
He says to recoup the cost involved makes it much harder to make water available for environmental use, as the water needs to be used for production to make construction stack up economically.
Water Holdings Hawke’s Bay director and Otane farmer Hugh Ritchie says the region’s freshwater problems have to be addressed.
“The do-nothing approach is not viable. We need to find a solution and there needs to be give and take on all sides,” he said.
“Having these conversations will be tough but they are necessary.”
Ritchie does not believe that larger scale store projects necessarily have greater detrimental effects on the environment than smaller projects if they are done properly, especially given new regulations and controls introduced by local and central government.
He says water security is not just a Hawke’s Bay issue. “It’s the whole of the east coast of NZ.”
He agrees with Robinson that finding multiple suitable sites in the region will be a challenge but says any work to find a future path is a positive step.
“We need options on the table,” he said.
“People will need to come to some middle ground to find a way ahead that is workable for everyone.”