Learn more about water quality in the Elk Valley, including how water is monitored, treated and managed, and the steps EVR is taking to support healthy watersheds and meet regulatory requirements.
Frequently asked questions about water quality in the Elk Valley
The Elk Valley Water Quality Plan is a long-term plan designed to protect the overall health of aquatic ecosystems in the Elk River watershed, including the Canadian portion of the Koocanusa Reservoir. The plan includes water quality targets to stabilize and reduce the quantity of mine-related substances in the watershed, with actions to achieve this goal.
Approved by the Province of British Columbia in 2014, the plan was developed using the best science available. It was informed by input from an advisory committee that included governments from Canada and the United States, Indigenous Nations and expert scientists.
Selenium is a naturally occurring element that is essential for human and animal health in small amounts but can cause adverse impacts at high enough concentrations.
Mining exposes rock to air and water, which can cause the selenium to be released and carried into the watershed.
Following approval of the EVWQP, key commitments and requirements were incorporated into a new valley-wide waste discharge permit (Permit 107517) issued by the Province of B.C.
Permit 107517 applies to all of EVR’s mines in the Elk Valley and sets water quality limits for selenium, nitrate and sulphate at locations throughout the watershed.
Yes, the Elk Valley Water Quality Plan’s goal is to stabilize and reduce selenium and the plan is working. Selenium concentrations downstream of EVR’s operations have declined to levels last observed approximately a decade ago, and that trend is expected to continue.
EVR’s four constructed water treatment facilities have capacity to treat 97.5 million litres of water per day and two additional water treatment construction projects currently underway are expected to increase capacity by an additional 30 million litres per day.
These facilities are removing between 95% and 99% of selenium from treated water. Selenium and nitrate concentrations have stabilized and are reducing downstream of treatment.
EVR has spent $2 billion building water treatment facilities as part of the Elk Valley Water Quality Plan.
EVR conducts extensive studies and monitoring of water quality and aquatic health, which includes regular water quality sampling at more than 170 water quality locations and over 100 biological monitoring stations in the Elk Valley and within the Koocanusa Reservoir.
The B.C. government oversees EVR’s monitoring programs. EVR’s Permit 107517 requires an Environmental Monitoring Committee which includes experts from B.C. Ministry of Environment and Parks, Ktunaxa Nation Council, EVR, Interior Health Authority, Ministry of Mining and Critical Minerals and an independent scientist to review reports and data required by the permit. It ensures independent oversight of the Elk Valley monitoring programs and provides advice to both EVR and the B.C. government.
EVR’s monitoring reports are publicly available on our website here.
The province also maintains and makes monitoring and compliance data accessible via the British Columbia Elk Valley Water Quality Hub.
EVR works with external registered professionals to undertake fish population monitoring. Results from 2025 show a stable fish population in the Upper Fording River, with Westslope Cutthroat Trout population numbers around the long-term averages for adults and juvenile fish. Monitoring report can be viewed on our website here.
EVR has participated in the International Joint Commission’s Reference on Transboundary Water Pollution in the Elk-Kootenai/y Watershed by providing a large volume of technical information and scientific studies, including monitoring data, participating in the Mitigation Technical Working Group and by hosting visits to our operations and water treatment facilities for members of the IJC Study Board, the Governance Body, Technical Working Groups and other stakeholders.
We are committed to constructive binational cooperation and to decisions grounded in sound science and reliable data, with the shared objective of ensuring continued protection of the Elk-Kootenai/y watershed, including Koocanusa Reservoir.
It’s important to note there are no fish consumption advisories for selenium for the Elk Valley or Koocanusa Reservoir.
A 2025 human health evaluation also concluded that eating fish from the Koocanusa Reservoir, including at the Ktunaxa preferred diet rates (e.g., 365 meals per year), does not pose an elevated risk from selenium exposure through consumption.
In addition, a 2023 Human Health Risk Assessment (HHRA) conducted by qualified professionals and overseen by a Working Group of experts from EVR, the Ministry of Environment and Climate Change Strategy, Interior Health, and the Ktunaxa Nation Council assessed the potential risks to human health from a wide range of mine-related substances in the Elk Valley and Koocanusa Reservoir. The assessment found:
- People eating an average amount of fish (e.g., 15 meals or less per year) have a low risk of health effects from selenium exposure. a
- People eating fish at the Ktunaxa preferred diet rates (e.g., 365 meals per year) could be exposed to more selenium and have a higher risk.
- Eating fish from Koocanusa Reservoir did not result in elevated risk from exposure to selenium.
A follow up 2025 human health evaluation also concluded that eating fish from the Koocanusa Reservoir, including at the Ktunaxa preferred diet rates (e.g., 365 meals per year), does not pose an elevated risk from selenium exposure through consumption.
Preventing constituents from entering the watershed in the first place and reducing the need for water treatment is a priority for EVR. Best practices for water management and blasting have been implemented to help reduce the release of constituents. EVR is also working to incorporate water quality considerations earlier in the mine planning process to minimize impacts where possible. We are constantly researching new technology, and we have broad portfolio of research and development projects underway to help reach our water quality goals.
Technologies from this research and development include:
Nitrate reduction: Our research and development program led to the development of a new nitrate prevention technique that uses liners that help prevent nitrate from blasting from coming in contact with water. This technique has been applied across our operations in the Elk Valley and a majority of blasts holes now use a liner.
Suboxic zones: Suboxic zones are designed to limit oxygen supply to the mine rock resulting in the development of conditions that have the potential to reduce leaching of selenium and nitrate. EVR is currently undertaking two full-scale suboxic zone source control research and development trial projects at our Elkview and Fording River Operations.