Castlerock aquifer in danger of overuse
Irrigators in part of Northern Southland will have to work together to preserve an overworked aquifer, Environment Southland says.
The North Range aquifer, which underlies the Castlerock groundwater zone, has an abstraction allocation of 180 per cent of its predicted aquifer flow-through.
This means that through past resource consents for water abstraction, which were based on a different model to one used now, the aquifer is vastly over-allocated.
The issue came to a head at an Environment Southland consents committee meeting late last month when an applicant sought to renew a water permit to abstract groundwater in the Lumsden-Mossburn highway area.
The committee heard the sustainability of the aquifer, which had shown periods of decline attributed to large-scale irrigation, was a concern and would need management controls in the future.
Councillor Jan Ridell said the council would be irresponsible to continue to allocate from the aquifer without resolving the issue.
"Council can't continue to over-allocate a resource when it's already over-allocated."
Cr Neville Cook said they seemed to be relying on information they did not yet have.
"I don't think that's what we want to be doing."
Data showed actual water use was 50 per cent of the total allocation, meaning the aquifer had a high theoretical allocation but lower actual use.
Future allocations therefore hinged on closing this margin, meaning the council relied on other abstracters in the area renewing their abstraction consents to align with new allocation limit.
The situation was problematic in that it relied on future agreement by third paries.
Cr Nicol Horrell said it was something the council needed to be reasonably clear on and he would like more information on it.
The applicant said in the past six months a "users group" had been set up to address water issues in the area.
The problem came from the big irrigators using the water, he said. The applicant's own application was minor.
The application had called for a 10-year consent but, based on Environment Southland's staff recommendation, it had been reduced to five years. This was because the consents of other abstracters would expire in the next year, enabling Environment Southland to issue shorter consents for them too and to align the consents.
Environment Southland consents manager Stephen West said declining this application would not make a lot of difference to the aquifer, and in recent years there had been a lot of improvement in the aquifer's water levels. Users were careful with the water allocation because they wanted the water and didn't want to draw it from so far down they couldn't get it, he said.
- The Southland Times
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