Faced with stricter new river low flow limits and the prospect of increased irrigation bans in an uncertain post-Ruataniwha Dam environment, water users in the Tukituki catchment have staked claims for billions of litres of Central Hawke's Bay's surface and underground water. Clinton Llewellyn reports.

Security of water supply looms as a critical issue in CHB since the demise of the dam.

Of the 19 water take consents issued for water storage in the Tukituki catchment, five consents have been issued in the past year.

Since November last year, five new surface water consent applications have been lodged with Hawke's Bay Regional Council seeking to extract a further 1.5 million cubic metres of water a year from the Tukituki and Waipawa rivers and their tributaries, for on-farm water storage projects.

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All in CHB and consisting of a mix of in-stream and out-of-stream dams and reservoirs, the applications have been made by existing consent holders, indicating they are trying to maximise their storage capacity ahead of the new low flow restrictions under Tukituki Plan Change 6 (PC6), which come into effect on July 1.

Meanwhile a group of 53 consent holders belonging to a CHB Water Users Group has approached the regional council for $50,000 towards a $65,000 study they have commissioned searching for a "collective community" solution to the security of water supply problem.

The consent holders — who say they are likely to be affected by irrigation bans under the new PC6 river flow limits — want to investigate if the defunct dam strategy can be replaced by a "more efficient and environmentally friendly" alternative to the current situation, where individual water users "have been left to fend for themselves".

In the background, eight applicants, including major dairy operations, have applications on hold with the regional council to collectively extract 17 million m3 of 'tranche 2' groundwater from the Ruataniwha Basin.

Currently 28.5 million m3 of 'tranche 1' aquifer groundwater is abstracted from zones 1 and 2 of the Ruataniwha Basin, north and south of the Waipawa River respectively. Both are at full allocation.

The Board of Inquiry into Tukituki Plan Change 6 determined that an additional 15 million m3 a year of 'tranche 2' groundwater could be extracted from across the two zones as a discretionary activity if the adverse environmental effects — particularly on surface water flows and river ecology — could be mitigated by river flow augmentation.

That means any tranche 2 groundwater consent holder would be required to offset a percentage of the water they take, by releasing it into rivers and streams at times of low flows.

The regional council's investment arm, HBRIC Ltd, the company promoting the dam and the Ruataniwha Water Storage Scheme (RWSS), had a claim to 10 million m3 of tranche 2 groundwater but withdrew its application last October, leaving the eight remaining applications.

Decided on a "first in-first served" basis, some applicants stand to miss out because of the 15 million m3 allocation limit. But with the amount of tranche 2 groundwater already oversubscribed, if the consents are approved then access to the groundwater will be concentrated in the hands of a relative few, with no groundwater left for anyone else in the two zones.

A regional council spokesman said the eight applications were on hold while they waited for details of the augmentation schemes.

"They are currently on hold, and they are looking at providing additional technical information so the effects of their takes can be properly considered and assessed."

A decision on whether the applications would be publicly notified was also yet to be made and could be months away, he said.

Aquifer takes sustainable?

The regional council has stated said that previous modelling studies (Baalousha 2008, 2009, 2010 and 2011) have indicated that groundwater abstraction from the Ruataniwha aquifer affects river flow, reducing the aquifer contribution to river flow in the Waipawa and Tukituki rivers.

A council agenda item last August also said "groundwater abstraction also reduces river flows during low-flow conditions and, when combined with surface water abstraction, there is the potential to extend the periods of time where a river flow is at or below the minimum flow".

The new low flow limits are already expected to greatly increase the incidence of 10-day irrigation bans in the Tukituki catchment in future.

Last August the regional council said that new scientific advice had indicated the volume of water being taken from the Heretaunga aquifer further north was at its "maximum acceptable level", with all takes having an effect on surface water bodies. The council said new consents for further water allocation from the Heretaunga aquifer was "no longer acceptable".

Significant costs, risk

CHB mayor Alex Walker said that on-farm water storage projects and accessing tranche 2 groundwater would come with "significant cost and/or risk" to the applicants.

"So they are not viable solutions for all water users. Time will tell how successful they are."

She said the uncertainty surrounding the security of water supply in CHB was a "sad consequence" of the removal of the RWSS as a partner to the Tukituki Catchment plan.

"I am extremely frustrated that no-one has been able to provide any guidance or information about how we move on from this."

The biggest single application for tranche 2 groundwater from the Ruataniwha basin has been lodged by Plantation Rd Dairies, up the road from Ms Hodge's deer farm.
The biggest single application for tranche 2 groundwater from the Ruataniwha basin has been lodged by Plantation Rd Dairies, up the road from Ms Hodge's deer farm.

However, she was proud of the collaborative effort of the CHB water users group and was looking forward to the regional council providing "more support" for their efforts in their Long Term Plan.

CHB regional councillor Debbie Hewitt said she also understood it would be both expensive and technically difficult for the applicants to access tranche 2 groundwater given the augmentation requirement.

She said she felt for water users in CHB operating in the void left by the dam.

"I have a huge amount of sympathy for them. The Tukituki catchment is the first cab off the rank in terms of implementing the National Policy Statement for Freshwater Management and all the hard lessons are unfortunately being learnt in CHB."

"But I also hear concerns from people downstream about what happens if we have this massive abstraction [of tranche 2 groundwater] and what the impacts are going to be."

Worried deer farmer

Waipawa deer farmer Rebecca Hodge is alarmed by the amount of groundwater being sought by the handful of applicants.

The biggest single application for tranche 2 groundwater has been lodged by Plantation Rd Dairies at Ongaonga, up the road from Ms Hodge's deer farm.

She said she paid a premium price for her 22ha deer farm on Swamp Road in Waipawa, where 150 deer supply velvet to Asian markets, because it was "summer safe".

"The aquifer is very close to the surface where my farm is. My farm well is 15m deep and it has never run dry in the 30-plus years it has been in," she said.

Though not an expert, she believed the aquifer and rivers were interconnected. She was worried about the impact of the increased groundwater takes if they were approved and feared the deep water beneath her property could be sucked dry.

"I have a few concerns with them taking so much water. There has been no real research done to find out how it will affect the land or people around the aquifer. It could very easily make my land summer dry, which will affect its value."

She also pointed to last year's example of Ongaonga residents' bores and wells drying up, which they blamed on increased irrigation. She was concerned it could happen to her property.

"It is a huge expense to dig a new well. Most of the families on my road are smaller lifestyle farms — how are they going to afford putting in wells which can easily cost in excess of $50,000? I know for me, that is most of my income off my farm.

"Besides it affecting the farmers, I don't think it's environmentally right to be sucking the aquifer dry and pumping water back into the river to fool the public into thinking that there aren't water problems," she said.

Irrigating dairy farmer

Plantation Rd Dairies has applied for approximately 6.1 million m3 of tranche 2 groundwater — around 41 per cent of the total amount available.

Managing director Kevin Davidson said water and irrigation had been attached to the farm since 1968 and Swamp Rd landowners had nothing to worry about.

"If they took some time to understand the hydrology of the area they'd understand that Swamp Rd is on a completely different section of the aquifer system. And at this stage, we only have an application in — it's not a done deal. We'll wait and see — it's a long journey."

With 1800 cows supplying nearly a million kg of milk solids a year, Plantation Rd Dairies is Fonterra's biggest milk supplier.

It is also a major water user and irrigator. It currently has a groundwater consent to take a maximum of 1.931 million m3 a year to irrigate 610ha of crops and pasture, as well as a surface water consent to use 98,250 m3 of water a week from a trench adjacent to the Waipawa River to irrigate 460ha of pasture, and to use in a dairy shed.

Mr Davidson said his dairy operation was currently using its full water allocation. He described the demise of the Ruataniwha Dam as a "dark day" for CHB, and he was "extremely" anxious about the new low river flow limits.

"It's going to cost CHB probably 1000 jobs. There's still a lot of people who don't realise what the impact of PC6 is going to be on their property."

He said more than 60 per cent of CHB's water was now classed as surface water and would come under restrictions from July — "no question".

He estimated the new low flow limits would result in irrigation bans of no less than 30 days every second year and up to 110 days some years.

"It will make a big hole in our business so we have to secure more reliable water." He said he was looking to phase out river takes with more reliable groundwater takes.

"It will also be a lot more environmentally friendly, because we won't have a direct coupling with the river like we do now for a good chunk of our water." Asked if he was concerned about the ability of the Ruataniwha aquifer to sustain such large groundwater takes, Mr Davidson pointed to the Board of Inquiry process.

"Irrigators spent in excess of $300,000 creating a water model that was put to the BoI, and that was adopted. And that states that on the Ruataniwha Plains, the water takes are sustainable, hence why they released the tranche 2 water.

But there are some conditions around that, which is one of the things we are working through," said Mr Davidson, referring to the augmentation requirements.

"It's a long journey and far from being solved yet. I've been involved in irrigation committees for the past 12 years, and to date we haven't achieved anything really. There's a lot of water still to go under the table."