Horowhenua District Council are working with a Maori landowners in a partnership that will see the region be the first to trial a native tree filtering system for treated wastewater and work towards improving the health of local waterways.

The Maori-owned land in the Waiwiri catchment is home to The Pot, a lake of treated wastewater and irrigation system for a pine tree plantation alongside.

When it was established more than 20 years ago it was a ground-breaking wastewater disposal system.

With the need to renew resource consents, Horowhenua District Council saw an opportunity to further enhance the site and trial the planting of native manuka and kanuka to replace some of the introduced pine trees, working with Maori landowners and other stakeholders.


Manuka and kanuka have antibacterial properties that are widely recognised, especially in New Zealand's honey industry.

By replacing some of the pine trees with 100,000 manuka and kanuka, they hope to see the trees' antibacterial properties help in cleaning the wastewater.

The native trees have unique properties for filtering pollutants and helping reduce leaching of nitrogen and pathogens, according to HDC.

The trial would also include other native species, including kahikatea, pukatea, rimu, tawa and swamp maire, planted for comparison.

The idea has been tested in a lab and small greenhouse trials at Lincoln University and Institute of Environmental Science and Research with positive results, however, The Pot will be the first to have the theory put into action at a large scale.

In previous discussions about the state of the Waiwiri catchment area Maori landowners had led the charge in development of a Catchment Care Group aimed at restoring the health of the Waiwiri Stream through fencing and planting.

The stream runs from Lake Waiwiri (known incorrectly as Lake Papaitonga) passing by The Pot before reaching the sea.

Muaupoko landowner Robert Warrington said that by working in partnership with all stakeholders, there is hope to free the choked-up stream, restoring its ecological balance and recreating an environment where native fish species can live and spawn.

HDC infrastructure services group manager Gallo Saidy said Maori landowners have always advocated native planting and doing things the natural way.

"It makes a lot of sense to work together," he said.

"[They] want to make sure the environment and waterways are clean and don't affect their fisheries and source of kai. We have that same responsibility to look after the environment."

Mr Saidy said the trial is the first of its kind, and if successful, will pave the way for wastewater management across the country.

"They have tested [the manuka and kanuka] at a small scale level with very positive results," he said.

"The $1.2 million project became possible after HDC received $607,173 from the Ministry for the Environment's Freshwater Improvement Fund."

The 10ha of pine forest would be harvested from next month. Manuka and kanuka planting would start next year and further areas of pine might also be replaced with natives.

This article is the view of one landowner and should not be seen necessarily as expressing the view of the Muaupoko Tribal Authority or Muaupoko iwi members.