Clearing the Water: The Reality of Selenium Treatment and Regulation

Written By Monique Simair

The Myth of Untreatable Selenium

As selenium has attracted more attention lately, I’ve noticed misinformation circulating. Some people claim there is no water treatment technology that can treat selenium to the guidelines. That is simply not true. There are treatment technologies that meet the discharge guidelines and targets set by federal and provincial regulators. Selenium is treated under the same frameworks, standards, and regulations as other contaminants. These systems also ensure that receiving environment guidelines are met, which includes a rigorously defined mixing zone. (Example from BC).

Discharge vs. Receiving Environment Criteria

The confusion comes from mixing up discharge criteria (what applies at the pipe) with receiving environment criteria (what applies after a mixing zone). This same approach applies to all contaminants, not just selenium. While the two have separate criteria, (e.g., MDMER vs CCME or provincial WQO), they are interlinked. For example, even if the selenium concentration meets the environmental criteria, and it is also lower than the end of pipe discharge criteria, it may be high enough at the discharge to trigger additional monitoring and studies to ensure the protection of the environment (e.g., section 9.1.d of the MDMER). So in addition to monitoring the water, biological endpoints such as the fish tissue is also monitored. This is the case for several elements, not just selenium.

Discharge Criteria and Environmental Criteria apply in different places

Discharge criteria and environmental criteria apply in different locations

Is this confusing? A bit. It’s confusing enough that groups make guidance documents to summarize the guidance documents (e.g., this guidance from the Mining Association of Canada). It requires effort to learn and understand, but it’s not insurmountable. However, it is an issue when the effort isn’t put into learning and assumptions are made.

For example, some people unfamiliar with water treatment and regulations demand that the receiving environment criteria should be met directly at the end of the pipe (which you now know is not how the regulations apply). This creates the false impression that effective treatment doesn’t exist, when their real issue is a misunderstanding of the regulations and their intended use. However, for other people, it is an actual disagreement with the regulations themselves, and in that case, the credible argument would be to say the regulations should be revisited, not that effective treatment doesn’t exist, because it does.

How Regulations Are Developed

It’s also important to recognize how regulations are developed. Dozens, if not hundreds, of scientists are involved over years and decades. They review scientific studies and baseline data, conduct new studies, compare approaches internationally, assess ecotoxicology, and examine the specific environments and wildlife at the receiving sites. There are universal criteria, but also site-specific considerations, and all of this is included in regulatory development.

Regulations also go through public commentary periods. This is happening right now in the Elk Valley, where a new framework is being developed specifically for that region in B.C. There have been opportunities for public input for years, with the most recent documents open for review over the past several months.

*edited to add links (thanks for the requests!)

Evolving Regulations

Saying that regulations should change is perfectly valid. Regulations evolve all the time. Below in the references section, I have included guidance documents from BC from 2014 (1, 2) and the 2025 update. If you peruse the the CCME guidance, it indicates what year the different criteria were developed and which are currently under review. But to do so credibly, you need to present a body of evidence and go through the same rigorous processes: data collection, peer review, and scrutiny. If you have that evidence, bring it forward so all can benefit. That is how science works.

Turning Standards Into Practice

For now, we operate with the best and most comprehensive information available. The current regulations have been reviewed by many scientists and informed by public input. My role in water treatment is to use regulations, or modified site-specific targets, as the goals to meet or surpass with treatment. There is also guidance on what information must be submitted about the water treatment selection and technology, such as section 6.4 of the BC JAIR.

It is also worth noting that every mine project has consultants who confirm the applicability of regulations to their site and use guidance to develop mixing zones. These assessments consider the ecosystem and the plants and animals present. Mechanisms exist to create site-specific water quality objectives for particularly sensitive environments. But these are always data-driven, reviewed, and include public stakeholder consultation.

The Answer

So, to the question: are there treatment systems that can meet selenium guidelines? The answer is absolutely yes, and they have existed for many years. Here is an old list of examples from 2020, there are many more now.

Science vs. Fear

Many people who are not scientists also weigh in on these issues. I welcome greater public engagement in science. But we need to remember: fear is the enemy of curiosity. When fear enters the equation, discourse closes. We stop debating ideas and start debating emotions. That is not science.

We need to notice when emotion is being used, whether to hype, to scare, or to sway, and pause. Recognize when the conversation shifts from science to emotion, and do a reset.

Finding the Balance

Think of it this way: strapping eight or ten seatbelts on a child does not add more safety. It does not create more seats either. The same is true here. In protecting the environment, safety is essential. But we must also ask: how many seatbelts are enough?

Monique Simair
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