IAH (NZ Chapter) Technical Meeting – Christchurch

Members and non-members welcome to this free event!

5:00 pm networking, 5:30 pm technical talk
Tuesday 21st April 2026

Davis Ogilvie Engineers, Level 1, 24 Moorhouse Ave, Addington, Christchurch

(Please arrive before 5:30 pm as doors lock at that time. Late arrivals, please text Carlos Rosado 021 224 6314)

Please RSVP before 16 April for catering purposes.

Presenter: Helen Rutter (Lincoln Agritech Ltd)

Nitrate state and trends: An assessment of historic data and the impact of a major irrigation scheme

Profile: Helen is a Senior Hydrogeologist at Lincoln Agritech Ltd. She has over 30 years’ experience in hydrogeological research and consultancy with an interest in groundwater and drinking water quality, shallow groundwater hazards, earthquake impacts on hydrogeological systems, hydrogeological aspects of ground source heat pump systems, and Canterbury Plains hydrogeology in general. She is a Chartered Geologist and a Senior Adjunct Fellow at the Waterways Centre at UC.

Abstract: In September 2025, ECan councillors declared a “Nitrate emergency” for the Canterbury region. This followed reporting that showed that across Canterbury, 36% of state-of-environment wells had nitrate concentrations greater than half MAV (5.65 mg/l) and over 60% of wells showed a very likely increasing or likely increasing trend. As reported by ECan, the gradual increase in irrigated land area and the associated rise in land use intensity since the 1990s, including a rise in the number of dairy farms, is believed to have resulted in increasing levels of nitrate leaching into groundwater.

Central Plains Water Ltd started in 2014–2017 and now provides water to 45,000 ha; of this, 25,000 ha represents new irrigation, where dryland was converted to irrigated land. The remaining 20,000 ha was land that was previously irrigated, mainly with groundwater. The consents to take water and discharge contaminants were highly contentious, and the outcome of the process was that CPWL have comprehensive monitoring requirements. Having been in operation for around 10 years, it is a useful time to assess the potential impacts of the scheme, and compare with what was predicted at the time of consenting.

The presentation will explore some of the longer-term data and patterns that we see in terms of nitrate variability, explain a little about the CPW scheme, and outline the trends that we are observing now.

Come along and hear about the nitrate challenge facing Canterbury’s groundwater and what a decade of monitoring data reveals.

Online Attendance

Those in Christchurch are expected to join in person for drinks, nibbles and networking. For those outside Christchurch who cannot attend in person, an online link will be provided.

Please RSVP using the button above and select “Online” – a meeting link will be sent to you before the event.