Avocado hearing: Aupōuri orchardists should stump up for new water supplies if school bores run dry

The area around Waiharara School, north of Kaitaia, has seen an explosion in avocado planting. Photo / Peter de Graaf

The Ministry of Education is calling for more monitoring of groundwater at some Far North schools to make sure their bores don't run dry due to avocado irrigation.

And if any school bores do dry up or turn salty the ministry wants orchardists to stump up the costs of setting up alternative water supplies.

Commissioners for the Northland Regional Council are in Kaitaia this week hearing submissions for and against 24 applications by the Aupōuri Aquifer Water Users Group to draw up to 6.2 million cu m a year. The water would mainly be used for avocado orchards, which are booming in the Houhora area north of Kaitaia.

Submitters include the Ministry of Education, which has seven schools — at Ngataki, Pukenui, Waiharara, Paparore, Awanui, Pukepoto and Ahipara — relying mainly on the Aupōuri aquifer for water.

Hydrogeologist Kenneth ''Keg'' Alexander said overall the council's proposals for monitoring the aquifer for salt water intrusion and groundwater depletion were ''relevant and robust'' — but he called for extra monitoring of some school bores, especially those drawing from the shallow aquifer which had not been assessed as thoroughly as the deeper shell bed aquifer.

Speaking on behalf of the ministry during Tuesday's hearings, Alexander said Ngataki School's 18m-deep shallow aquifer bore need to be monitored to make sure it wasn't affected by pumping from the deep aquifer at orchard bores 1.4km and 1.9km away.

The Ministry of Education is calling for closer monitoring of Waiharara School’s bores if applications to draw up to 6.2 million cu m of water from the Aupōuri aquifer get the green light. Photo / Ivor Bates

Waiharara School, with a 38m-deep bore in the shallow aquifer, was just 200m away from a proposed deep aquifer bore, yet there was no monitoring planned of the shallow aquifer near the school.

At Pukenui School, on the other hand, he believed the proposed monitoring regime was sufficient, and he expected the other schools would be unaffected because they were far enough away from orchard bores.

Ahipara School was a good distance, 4.5km, from the nearest extraction bore, but because it was just 800m from the coast its bores were at risk of saline intrusion. They also needed to be monitored for salt levels.

If any school bore became unusable due to salt intrusion, the consent holders should be required to immediately provide the school with a temporary water supply until a permanent alternative could be provided at the consent holders' expense, he said.

Alexander said his recommendations were ''relatively small and prudent'' but would help safeguard water supplies at the seven schools.