Management transfer
Currently, AMD, including that resulting from historic Crown mining, is being managed by BT Mining Limited, which has operated at the site since 2017.
Once commercial mining concludes, the Crown will assume responsibility for AMD management.
As of 1 October 2025, this function has transferred from Treasury to LINZ, reflecting LINZ’s capability to manage complex environmental risks.
Background
Stockton Mine, located near Westport, is New Zealand’s largest coal mine.
AMD occurs when certain rock types are exposed to air and water, producing acidic runoff that can damage local streams and pose safety risks.
Although AMD naturally diminishes over time, its effects will persist for more than a century after mining operations cease.