A controversial consent to take billions of litres of water a year from a Far North aquifer to feed avocado orchards is being appealed by the Department of Conservation.
DoC is appealing to the Environment Court against consents granted to take water from the Aupōuri Aquifer for avocado growing.
More than $145 million of Northland horticultural development across 24 properties on the Far North's Aupōuri Peninsula has gained consents to take more than 4.5 million cubic metres - 4,520,000,000 litres - of water each year from the underground aquifer.
Northland Regional Council (NRC) on August 31 released a decision by Commissioners David Hill and Peter Callander granting the applications by 22 parties referred to as the Aupōuri Aquifer Water User Group (AAWUG).
More than 1800 Olympic swimming pools of water could be taken from the aquifer each year, enabling one of New Zealand's biggest development of its type.
The consent allows more than 1000 hectares from Ahipara in the south to Ngataki in the north to be irrigated with 4.52 million cubic metres of groundwater annually.
However, Director-General of Conservation Penny Nelson, is appealing the decision.
DoC Kaitaia operations manager Meirene Hardy-Birch said the department was not, in principle, against the water being taken from Aupōuri aquifer.
But it was not confident around the adequacy of data and other aspects being used as the foundations for some of the critical management of the aquifer needed into the future.
This was important because the health of the intrinsically-linked Aupōuri aquifer and the 124 dune lakes and streams across the consented area could not be reversed, once damage was done.
The internationally important 4000ha Kaimaumau wetlands are at the heart of DoC's environmental impact concerns, focusing on groundwater extraction impacts for natural water features including dune lakes and streams.
Hardy-Birch said a kaitiaki liaison group and two independent panels to be set up as part of consent conditions had been a positive move, but concerns over monitoring and management control, some of which was inadequate, needed addressing.
Some of the modelling used for monitoring groundwater taken was based on assumptions and uncertainties.
The DoC appeal challenged proposed trigger points used to alert if too much water was being taken. It said the consent baseline point for setting these was to start after the water takes began.
Hardy-Birch said time needed to be spent, ahead of the water takes starting, to make sure of satisfactory baseline data collection.
She said current monitoring and/or long term records were unavailable for some of the monitoring bores and surface water levels.
Proposed monitoring locations were not close enough to sensitive surface water features.
The AAWUG consent follows an earlier 2018 collective water take consent application from the Motutangi-Waiharara Water Users Group (MWWUG) by 17 avocado growers. DoC also appealed this to the Environment Court. It then went to the High Court. MWWUG horticulturists were finally able to start drawing water last year.
Hardy-Birch said the modelling used to monitor groundwater takes for the MWWUG group had not yet had long enough to be a reliable indicator of how things might progress with the AAWUG consent users.
The September 20 DoC appeal document said there would be difficulties isolating the effects on the aquifer from the two collective water takes in combination.
The commissioners on August 31 said while the sum total abstraction sought was large in terms of quantity, the evidence clearly indicated it was relatively small in comparison with the annually available throughput of the aquifer and was sustainable from that point of view.
NRC said there was an estimated 2850 million cubic metres of groundwater stored within the overall Aupōuri aquifer system in an average year. AAWUG originally sought 4,606,260 cubic metres annually.
NRC said expert evidence suggested that originally-sought quantity was 0.16 per cent of the 2850 million cubic metres of Aupōuri aquifer groundwater stored in an average year. It was also only 1.9 per cent of the estimated 238 million cubic metres NRC used to allocate water from the overall Aupōuri aquifer system.
Commissioners granted a total of 4,519,984 cubic metres a year could be taken.