Minister checks out a Lagmhor leak

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Principal hydrologist Bob Bower, of Golder Associates explains the managed aquifer recharge trial to the Minister for Primary Industries, Nathan Guy.

By Maureen Bishop

The involvement of so many community groups in the Mid Canterbury trial project to recharge aquifers with clean water made it a first for the southern hemisphere, the Minister for Primary Industries, Nathan Guy, was told during a visit to the site.

The promising results from New Zealand’s first such project were explained to the minister by project leaders and participants.

The project has been operating in the Lagmhor area, just outside Ashburton, since June last year, and results for boosting ground water levels and diluting nitrogen have exceeded expectations.

The project is designed to replenish declining groundwater levels, restore flows in coastal drains and improve water quality in the shallow aquifer.

Water from Ashburton District Council unused stockwater consents taken from the Rangitata River is diverted to the site, via the Valetta Irrigation Scheme. Natural sediment settles before the water enters a leaky pond and percolates into the aquifer.

The Ministry for Primary Industries (MPI) has allocated $312,000 to the trial. The funding comes from MPI’s Irrigation Acceleration Fund.

Bob Bower, principal hydrologist with Golder Associates, told the minister the trial was showing really promising results, with ground water levels increasing and nitrate concentrations dropping from 13mg per litre to 4.6mg.

“This trial is not meant to be put on a pedestal. It’s just one of the things we are looking at,” Mr Bower said. “A lot of things are being done on-farm, too.”

There were around 1600 aquifer recharge projects around the world, he said, but the Ashburton trial was the first in the southern hemisphere where the community had come together to manage groundwater.

It is expected that two billion litres will go into the aquifers by the end of June..

A governance group has recently been established to run the project, together with a technical working group. A technical update meeting was held on Monday and a strategic planning meeting will be held on May 26.

The Ashburton Water Management Zone Committee is backing the continuation of the project for five years and has sought support from the Ashburton District Council to continue to take water and from Environment Canterbury to continue with monitoring.