Manawatū District celebrates nearly seven years of wastewater irrigation
Seven years on from its introduction, the Manawatū District Council’s dual discharge wastewater system is continuing to deliver strong environmental benefits while showcasing innovation in action.
Each year, from November through to April (weather dependent), treated water is applied across 200 hectares of Council-owned land using five centre pivot irrigators and three travelling irrigators.
This season alone, over 581 million litres of treated wastewater have already been discharged to land. Since the system began operating, more than 3.8 billion litres have been irrigated, significantly reducing the need for river discharge during naturally lower river levels.
Importantly, the irrigated land is also used as a cut-and-carry operation managed by a local contractor. The resulting pasture is distributed across local farms, supporting agricultural productivity within the district and closing the loop between water reuse and land-based outcomes.
“This system is about making the most of a resource that’s already been treated to a high standard,” Adam Jamieson MDC Operations Manager explains. “By applying it to land at the right time and in the right conditions, we’re achieving both environmental protection and practical reuse.”
During the winter months, when irrigation is not suitable, the system transitions to one of the largest constructed wetlands in New Zealand. Home to over 80,000 plants, the wetland provides natural filtration before water is discharged.
The wetland is capable of filtering up to six million litres per day through a three-day process, helping to improve water quality and protect the health of the receiving environment.
In addition to its treatment role, the wetland has become a thriving ecosystem, supporting native birdlife and aquatic species, highlighting how infrastructure can enhance biodiversity as well as environmental performance. This year, the wetland system is set to extend through a vertical bay to complete the three-bay system.
As the land irrigation system approaches the end of its seventh year, it stands as a strong example of how thoughtful design and long-term investment can deliver lasting benefits for both the environment and the community.
Here’s to another great irrigation season!