Investigation of nitrate in Gore’s groundwater supply
Environment Southland’s staged scientific investigation to better understand nitrate levels in groundwater supplying Gore’s drinking water is underway. The work builds on our ongoing investigation, following a spike in nitrate levels in Coopers Wells in July 2025 above drinking water standards.
Environment Southland has not identified any specific cause for the nitrate spike in Gore’s drinking water supply.
Acting Chief Executive Rob Phillips said it is understandable that Southlanders living in Gore and other nitrate hotspot areas may be concerned about elevated nitrate levels in groundwater.
“Environment Southland is focused on working with the other agencies involved in this issue to reduce uncertainty, better understand the risk, and support long‑term water management for the Gore community.”
Environment Southland’s science and monitoring programmes are built on decades of data, monitoring and investigations, and the recently released report, ‘Nitrogen Contamination in Southland Groundwater’, helps clarify the complexity of nitrate levels in Southland’s groundwater.
The report was commissioned as part of the initial response to the nitrate spike in Gore’s drinking water to bring together decades of published research, monitoring data, and regional modelling, and to present it in an accessible way, making it easier for communities and decision-makers to understand and respond.
“This work draws on the expertise of our scientists, who have a deep understanding of the complexity of groundwater systems in Southland. Our team has robust quality assurance and peer-review processes, ensuring evidence is credible for our communities and future decision-making.”
The report summarises the current state of knowledge on the magnitude and extent of groundwater nitrate contamination in Southland. Data reflects the combined effects of intensive land use and the underlying vulnerability of many of the region’s groundwater systems.
“Our science-led investigation is about understanding the system and cause(s) well enough for all agencies to act effectively in supporting the long-term management decisions for Gore.
“It’s important for our region that we work together to reduce nitrate levels in groundwater. This is a shared challenge, from the water source to the tap, and we need to address it collectively.”
The staged approach focuses on identifying broad nitrogen source types, understanding groundwater flow and age, and how the aquifer at Coopers Wells is replenished. Land use mapping and statistical modelling analysis will also provide insights into the impact of land use change on groundwater nitrate levels.
Results from the early stages of the investigation will be shared with the community once completed. The insights gained will inform further work.
“We’re committed to keeping communities in groundwater nitrate hotspot areas informed and involved in finding solutions, and supporting practical steps to reduce nitrogen losses.”
To read more about the investigation, visit www.es.govt.nz/gore-nitrate
