Manawatū District Council and mana whenua Ngāti Kauwhata Iwi have been developing a constructed wetland at the Manawatū Wastewater Treatment Plant on Kawakawa Road. This will see approximately 6 million litres of treated wastewater go through an extra filtration process before it re-enters the river systems of the Manawatū.

Earthworks on the wetland began in August 2022, with the movement of approximately 30,000 m3 of soil and the construction of an access road. Material for the access road was supplied by Central Environmental from their concrete crushing operation, which uses at the Council’s Resource Recovery Park located at the treatment plant.

The project has reached a significant milestone with the start of planting of over 80,000 native plants. These plants have been specifically selected for their treatment properties and ability to break down and extract remaining nutrients in the treated wastewater. They are grown at Council’s own Kawakawa Nursery and planted by the The Te Whakahaumaru te Whenua Team (Jobs for Nature) of Ngāti Kauwhata.

Treated wastewater going to the wetland will take up to three days to travel from the inlet to the outlet, where evapotranspiration will reduce some of the volume and the balance will be released into the Ōroua River.

This is just one of the projects that Manawatū District Council is doing to improve the quality of the proportion of the treated wastewater that eventually flows into the Ōroua River, which will further enhance the quality of the freshwater in the river.

Council have invested heavily in infrastructure to improve the quality of treated wastewater going into the river and are discharging to land through irrigation during the summer months.

In 2015 the Ōroua River Declaration was signed by both Council and Ngāti Kauwhata which stated a joint commitment to work towards the continued improvement of the quality, health and wellbeing of the Oroua River into the future.
 

Ngāti Kauwhata Chairman, Dennis Emery agreed that lifting the Rahui, which has been in place since the 1960’s, was tantamount to the Iwi’s ultimate goal of stopping all discharge into the river, and continues to be part of its current Waitangi Tribunal claims process.

The planting of the first bay of the constructed wetland was completed by July, and it is expected to be operational by late 2023.

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