Mount Milligan’s 2035 Permit Clears the First Gate in a 2045 Mine-Life Plan

Centerra Gold’s January 2026 permit amendments give Mount Milligan legal room to operate through 2035 and authorise a 10% increase in plant throughput from 2028. The decision removes a near-term regulatory constraint and supports a larger plan to extend the British Columbia copper-gold mine to 2045.

The permit is significant, but it is not the final approval for the full mine-life extension. Centerra’s pre-feasibility study contemplates additional infrastructure, including a second tailings storage facility, and the company expects to begin that permitting work in 2027. The investment case therefore divides into two stages: extracting value from the approved 2035 envelope, and proving that the longer 2045 plan can be permitted and built on schedule.

Throughput growth is now authorised

The amended environmental assessment certificate and related permits allow increased stockpile capacity and a 10% plant-throughput expansion beginning in 2028. More stockpile flexibility can help the mine blend ore and manage seasonal or operational disruptions, while higher throughput provides a direct route to more payable metal if recoveries and feed quality hold.

Centerra’s 2045 pre-feasibility study outlined a US$186 million growth-capital programme. The appeal is that this is an expansion of an operating mine with established infrastructure, workforce and processing knowledge, rather than a greenfield build. The risk is that brownfield projects must be executed around ongoing production and within an increasingly complex tailings and water-management system.

Tailings remain the long-dated constraint

A mine-life extension of this scale creates a waste-storage problem as much as an ore-processing opportunity. The existing permit covers operations through 2035, but the full 2045 case requires a second tailings storage facility and further approvals. Centerra expects that permitting process to begin in 2027.

That distinction matters for valuation. The permitted 2035 mine plan has greater certainty and can support near- and medium-term cash-flow estimates. Production beyond that point carries additional regulatory, engineering and capital risk. Investors should not assign the same probability to every year in the 2045 schedule simply because it appears in a technical study.

British Columbia’s expedited schedule is encouraging, but the next application will likely receive close scrutiny around water, tailings stability, Indigenous engagement and closure obligations. Delays would not necessarily impair current operations, but they could reduce the value of the later mine-life extension.

Copper and gold must be analysed together

Mount Milligan is not a pure gold mine. Its economics depend on copper production, gold by-product credits, concentrate terms and the relationship between feed grade and throughput. Higher plant capacity can offset declining grades, but it can also increase unit volumes of tailings and expose the mine to recovery losses if the circuit is pushed too aggressively.

Centerra’s strong balance sheet gives it the ability to fund the approved growth programme internally. That reduces financing risk, but capital discipline still matters because spending at Mount Milligan competes with shareholder returns and other development opportunities.

The January permit is therefore a meaningful de-risking event, not a complete solution. It clears the first regulatory gate, enables a defined throughput increase and extends the operating horizon. The next test is whether Centerra can deliver the growth capital, maintain recoveries and secure the second tailings approval needed to turn the 2045 plan into an operating reality.