Arctic Gold and Silver (AGS) Mine Legacy Site Remediation
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Location
The site of the Arctic Gold and Silver (AGS) mine and tailings storage facility is located approximately four kilometres south of Carcross, Yukon, on Category A Settlement Land on Montana Mountain, within the Traditional Territory of the Carcross/Tagish First Nation (C/TFN).
Site History and Environmental Context
Gold and silver mining at the AGS site began in the late 1800s and continued intermittently until 1969, when operations ceased. The closure left behind approximately 27,000 cubic metres of acid-generating tailings. Mill structures were dismantled in the late 1980s and early 1990s.
The first remediation took place in 1999, focusing on tailings consolidation, soil capping, and site stabilization. Despite these measures, monitoring has shown elevated arsenic levels in soils and cadmium in groundwater and surface water, requiring ongoing assessment and management.
AGS is managed by Crown-Indigenous Relations and Northern Affairs Canada and funded through the Federal Contaminated Sites Action Plan.
Areas of Environmental Concern
- Tailing Impoundment
- Former Processing Plant Area
- Spilled and Windblown Tailings
- Unnamed Lake (including reservoir stream)
Environmental and Health Concerns
The remaining 27,000 cubic metres of tailings and contaminated soils pose risks to the environment and traditional food sources.
- The site is fenced and marked with warning signs in English, French, and Tlingit.
- Recreational use and harvesting of food or medicinal products are not recommended.
- High risk from incidental ingestion of arsenic and lead in soil.
- Drinking surface water from Unnamed Lake could expose people to cobalt and manganese.
- Terrestrial plants and invertebrates face potential harm from arsenic.
- Aquatic life in Unnamed Lake is at risk from arsenic in sediments and metals (aluminum, cadmium, cobalt, copper, iron, zinc) in water.
- Upstream reservoir shows cadmium concerns, but low risk downstream toward Bennett Lake.
Priorities and Next Steps
The AGS Mine site is undergoing long-term remediation and will be safe for community use. Current priorities and planned actions include:
Implemented Safety Measures:
- Posted signage advising against drinking water from Unnamed Lake until mitigation is complete.
- Maintain monthly site visits and reroute trails where needed to protect public safety.
Soil and Habitat Remediation:
- Target arsenic- and lead-contaminated soils in tailings areas, with additional sampling to refine the zones requiring clean-up.
- Conduct a detailed "halo zone" study—sampling soil, plants, and berries—to better define risks and guide restoration.
Aquatic Investigation:
- Undertake a comprehensive assessment of Unnamed Lake and reservoir stream to map contamination in sediment and surface water and to identify effective remediation options.
Monitoring and Evaluation:
- Maintain frequent monitoring of soil, groundwater, and surface water to track conditions and evaluate remediation effectiveness.
- Assess environmental risks to help set priorities for future clean-up activities.
Community Engagement and Capacity Building:
- Work closely with C/TFN to ensure Traditional Knowledge informs all decisions.
- Support local environmental monitoring and training programs in partnership with Yukon University and Haa Chάli.
Remediation Planning:
- A final remediation plan has not yet been selected. Findings from ongoing studies and community input will guide the choice of culturally appropriate technical solutions and restoration measures.
- WSP (a global engineering and consulting firm) is developing remediation options and will be presented to CIRNAC and C/TFN in early 2026 for review and consideration.
Collaborative Governance
In July 2025, CIRNAC and C/TFN signed a Governance Agreement and two committees were established to provide oversight on the project; the Governance Committee and the Operations Committee.
The Carcross/Tagish Development Corporation’s Haa Chάli Limited Partnership leads much of the technical work, creating local employment and training opportunities in the region.
Yukon Devolution Transfer Agreement
Under the 2003 Devolution Transfer Agreement, AGS is classified as a Contained Site. Canada retains management and funding obligations for Contained Sites, which are distinct from Type roman numeral 2 and Waste Sites. Crown-Indigenous Relations and Northern Affairs Canada (CIRNAC) continues to manage the site in collaboration with the Government of Yukon and C/TFN, ensuring the integration of Traditional Knowledge.
Arctic Gold and Silver Mine – Key Timeline
December 2025 – Terms of Reference and Closure Goals and Objectives approved, Engineering Contract Signed
CIRNAC and C/TFN held their first Governance Committee meeting to review and ratify Terms of Reference and Closure goals and objectives.
C/TFN Development Corporation (CTEC) – following a competitive tender process, CTEC awarded the first phases of engineering for closure to WSP Global Inc.
July 2025 – Governance Agreement Signed
CIRNAC and the CTEC signed a Governance Agreement to guide ongoing site management and future remediation work.
May 2025 – Remedial Options Analysis
WSP produced a report that evaluated a range of remedial approaches for the site. Three of the more promising approaches received a Class 5 cost estimate.
March 31, 2025 – Preliminary Quantitative Risk Assessment (PQRA) Completed
WSP delivered a comprehensive PQRA for CIRNAC, confirming human and ecological risks and outlining recommendations for further remediation and community engagement.
January 2023 – New Risk Assessment Contract
CIRNAC contracted WSP to conduct the PQRA.
2022 – Latest Environmental Monitoring
Hemmera documented ongoing acid rock drainage and elevated metal concentrations in groundwater and surface water.
2020 – Conceptual Site Model
Jacobs prepared a detailed model of contamination sources, transport pathways, and exposure zones.
2015–2019 – Detailed Site Studies
Sampling of soil, sediments, berries, and aquatic invertebrates revealed elevated levels of arsenic, lead, cadmium, and other metals.
2012–2014 – Phase roman numeral 2 Environmental Site Assessment
Drilling, soil and groundwater sampling, installation of monitoring wells, and water analysis to further characterize contamination.
2010 – Phase roman numeral 1 Environmental Site Assessment
Records review and on-site inspection to identify potential contamination issues.
2001–2011 – Performance Monitoring
Routine inspections and groundwater studies revealed decreasing effectiveness of the tailings cover and ongoing metal leaching.
1999 – Major Remediation
"Consolidate and cover" project completed: tailings and spilled material collected and capped to limit water infiltration.
1997 – Phase roman numeral 3 Environmental Assessment
Confirmed tailings were acid-generating and leaching metals, posing risks to human health and the environment.
1990–1993 – Initial Federal Screening
Arctic Environmental Strategy "Action on Waste" program assessed environmental and physical risks.
1965–1969 – Mine Operation
Gold–silver mining and milling on Montana Mountain.
Mill built in 1968 produced ~23,000 cubic metres of tailings.
Tailings impoundment and accidental tailings spills created the Unnamed Lake area.
Ongoing Investigations (present and past)
Routine test pitting, surface- and groundwater monitoring, and long-term sampling continue to track site conditions.