Last updated on February 09, 2026.
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Water treatment performance indicators
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Trends in water treatment
The figure below shows how much water is being treated and how much selenium and nitrate are being removed.
Note: This figure is interactive. Click on a site in the legend to add it or remove it from the graph or double-check to isolate one site. Use the pan and zoom features on the upper right side of the figure to look at specific set of years. Hover over a site/month to view monthly data.
The amount of water treated has increased over time as new facilities have begun operating and are ramped up to full capacity. As more water is treated, more nitrate and selenium are removed from the effluent. The amount of water treated also changes throughout each year depending on many different factors.
- The capacity of the treatment facilities. The size of the pipes, pumps, tanks and filters determine the maximum amount of water that can be treated. This is fixed for each facility based on how it is built.
- How much water is available. During periods of lower streamflow (such as late summer and winter), less water is available than the capacity of the facility. When this occurs, facilities operate at less than capacity.
- The amount of substances in the water. Some of the facilities use bacteria to consume and remove substances. The amount of substances (e.g. nitrate, selenium) removed is limited by the number of bacteria. Occasionally, the amount of a substance is too much for the bacteria to consume and the facility needs to operate at a lower rate to ensure the water is effectively treated.
- Shutdown periods for maintenance. Facilities require routine maintenance and repairs. The facilities may operate at lower capacity or be shut down for periods of time to allow for maintenance or repairs to occur.
EVR’s water treatment plan
EVR’s strategy for improving water quality in the Elk Valley relies heavily on water treatment. Water treatment is necessary to reduce the impacts of historic and current mining.
A document called the Water Quality Mitigation Plan describes how EVR proposes to add and expand treatment in the Elk Valley. More treatment will help EVR achieve water quality limits and meet the goals of the Elk Valley Water Quality Plan. The most recent version of EVR’s Water Quality Mitigation Plan was submitted in 2025 and is under review by regulators. A copy will be posted once review is complete.
EVR is also developing and testing ways to prevent poor water quality in the first place. This approach is called ‘source control’. It will help reduce reliance on water treatment in the future. For example, the amount of nitrate released into the environment is now being reduced by lining the holes where explosives are placed for blasting. New waste rock piling techniques are also being tested which, if successful, would reduce the release of selenium, nitrate and sulphate into the environment.
The 2025 Water Quality Mitigation Plan proposes to add three new or expanded treatment facilities within the next year, plus four more between 2027 and 2042. The plan is based on predictions of how water quality will change over time using a sophisticated water quality model and considering all historic and approved mining.
