On‑Farm Water Outcomes.

Central Plains Water Limited (CPWL) has taken part in a joint initiative with Environment Canterbury (ECan) and the Ministry for the Environment to better understand how farm practices are influencing nitrate trends in groundwater.

The modelling helps connect the dots between shareholder actions on farm and the results we are now beginning to see in the aquifer.

By accounting for rainfall, climate variation, and the natural lag time in groundwater, the model is able to show:

1. When and where improvements from on-farm actions are likely to be detected.
2. Whether good management practices are enough to reverse degrading trends.
3. Where additional steps may be needed if improvements are not seen within expected timeframes.

CPWL’s monitoring wells sample groundwater with a median age of <5years, compared to the median age of the ECan wells >30 years, therefore the water in the CPWL bores is more responsive to change and we can see sooner the impact land owners’ practice

• 2015–2018: Farm environment plans introduced; actions to mitigate nitrogen losses begin.
• Post-2018: Nitrate leaching from farms reaches its peak.
• Declining concentrations in many wells from early 2020s could be caused by mitigation actions, but further work is being done to confirm this because groundwater can be influenced by climate cycles and take a long time to respond as it flows through the aquifer.

Together, results from CPWL and ECan sites provide a critical feedback loop — ensuring actions taken on farm are delivering real outcomes and helping identify where further steps may be required.

Shareholders’ commitment to better land management has been central to this progress. CPWL will continue to provide long-term monitoring to ensure transparency and support future decisions for the health of Canterbury’s groundwater.

This latest monitoring update builds on earlier modelling work linking shareholder land management practices to groundwater outcomes.