Endeavour Inlet mine site under review for environmental remediation

Conservation Minister Tama Potaka noted the area is heavily used by visitors, with the Queen Charlotte Track passing through valley flats near the inlet.

A former antimony mine site in the Marlborough Sounds is set for a detailed environmental investigation after concerns about lingering contamination and landscape impacts triggered a joint government response focused on remediation and long-term protection. The Endeavour Inlet site, located about 27 kilometres northwest of Picton, was mined between the 1870s and early 1900s. Waste rock from those operations remains scattered across parts of the conservation land, raising questions about how much material may still be affecting soil, waterways, and nearby coastal ecosystems.

The Ministry for the Environment and the Department of Conservation have each committed $232,000 to support a two-year programme that will map risks, assess contamination levels, and develop practical options for managing the site. The work will include both environmental testing and planning for potential stabilisation measures if required.

Focus on contamination risks and changing coastal conditions

The investigation will look closely at how mine waste may be influencing the surrounding environment, including soil health, freshwater flow through the valley, and conditions in Endeavour Inlet itself. Scientists will also examine whether contaminants from the old workings could move further through erosion or water movement, especially during heavy rainfall events.

Sea level rise has been added as a key factor in the assessment. The site sits close to the shoreline, where shifting coastal conditions could alter how any remaining waste materials behave over time. That means the project will not only assess current impacts but also how risks might evolve in the coming decades.

Balancing conservation, recreation, and heritage values

Conservation Minister Tama Potaka noted the area is heavily used by visitors, with the Queen Charlotte Track passing through valley flats near the inlet. The track attracts hikers and cyclists throughout the year, while nearby waters support shellfish gathering and sit alongside holiday homes and lodges. A stream runs from the valley down into the inlet, creating a direct pathway between the historic mine site and the coastal environment. That connection adds pressure to ensure any remaining contamination does not affect water quality or marine life used by both residents and visitors.

The project will also consider whether physical stabilisation work is needed on-site, along with steps to protect heritage features linked to the mining history. Any recommended actions are expected to focus on reducing risk while maintaining access to the wider recreational landscape. The investigation aims to give a clearer picture of how the legacy of historic mining continues to interact with a sensitive coastal environment, and how best to manage those impacts without limiting the area's use or ecological value.