BC’s Environmental Assessment Office green lights expansion at Centerra Gold’s Mt Milligan
British Columbia’s Environmental Assessment Office (EAO) has approved an amendment to the Centerra Gold-owned Mt Milligan copper-gold mine environmental assessment certificate, authorising the mine near Fort St James to increase production and continue operations until 2035.
The EAO said its Chief Executive Assessment Officer “made the decision after carefully considering the conclusions of the EAO’s comprehensive nine-month review of Thompson Creek Metals Company Inc.’s application to continue mining at the site. The review examined potential effects on nearby communities and First Nations, water and fish habitat, air quality and noise, and considered safety risks, First Nations rights and cumulative effects.”
As a priority project, the EAO integrated its assessment of the complex project amendment with permitting reviews by the ministries of Mining and Critical Minerals and Environment and Parks into one review. Through this co-ordination, regulatory agencies were able to share expertise and reduce duplication, shaving more than a year off the usual timeline for provincial reviews, while upholding environmental protections and consultation obligations with First Nations. Permitting decisions are expected soon.
The EAO’s assessment determined that with the application of legally binding conditions, continuing mining operations would not create significant new impacts, and impacts can be appropriately mitigated.
The EAO has updated the requirements in the project’s environmental assessment certificate to address the expansion’s impacts on the environment and people. These include:
- ensuring First Nations have the opportunity to participate in developing and implementing environmental monitoring and baseline data collection programs
- monitoring and reporting wildlife mortality along transportation corridors
- developing a plan for wetland reclamation and replacement areas when the mine closes
The company must continue to comply with the existing conditions and mitigation measures in the environmental assessment certificate, which protect the environment, regulate water and waste management, dam safety and emergency response, and uphold First Nations rights and traditional uses. Permits, if issued, would include additional requirements for mitigation measures to address the expansion related to waste-rock management, surface and groundwater, air and sound pollution, safety protocols, closure and post-closure water quality, and reclamation requirements.
The Mt Milligan mine employs approximately 600 people in the region. If all other authorisations are approved, the mine expansion will generate additional jobs during construction and expanded operations and contribute as much as C$450 million in additional economic benefits to the region.
Centerra Gold’s Thompson Creek Metals Company Inc operates the Mt Milligan copper-gold mine approximately 90 km northeast of Fort St. James. The environmental assessment certificate for Mt Milligan mine was issued in 2009 after a comprehensive environmental assessment.
The existing Mt Milligan copper-gold mine site includes an open-pit mine, tailings storage facility, road access, transmission line and rail shipping facility. In March 2025, Thompson Creek Metals Company Inc applied to extend the operating mine’s life and increase production. The mine-life extension authorizes an 80-hectare expansion to the disturbance area for construction materials and an increase in production from 60,000 t to 66,500 t of ore per day by deepening the pit.
The amendment also includes building new infrastructure, altering the transportation route, increasing the tailings storage facility dam height from 1,095 m to 1,121 m above sea level, establishing a new waste-rock stockpile and updating the reclamation and closure plan for the mine.
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