ERA disclaimer | The debate over what threshold concentration of selenium results in a negative effect on fish is ongoing. Numbers reported in lab experiments or in specific areas are hard to extrapolate to natural real-world conditions. The information below has been compiled by ERA staff and reviewed by experts in the field of ecotoxicology. However, ERA is not an authority on selenium, and research and debate continues.

What can we learn from this graph?

According to these data, the average selenium concentration in the Elk River is about 5 µg/L by Elko, and 10 µg/L by Sparwood. In contrast, ERA found that non-mine-affected tributary creeks in the Elk Valley have an average selenium concentration of 0.4 µg/L, indicating that Elk River mainstem selenium concentrations are on average 12-25 times higher than natural levels.

Over the last few years, the rate of selenium increase shows some signs of slowing down at the Sparwood monitoring site (orange line) but not at the Elk River outflow into Lake Koocanusa by Elko (teal line). The actual concentrations of selenium are not yet decreasing at either location. On average, selenium levels have increased by more than 4 times in the Elk River between the first and last decades of recording. Moreover, some streams closer to mine sites show higher levels: for example, close to the Fording River mine a Compliance Test Point monitored by Teck (Site FR_FRCP1), had concentrations of selenium reach 674 µg/L in 2020 (Teck 2020 FRO LAEMP). Selenium concentrations in the Elk River have not been below the BC Aquatic Life Guideline levels* (which are designed to protect all aquatic life, including the most sensitive species) since 2009, and frequently exceed the BC Source Drinking Water Guidelines at the Sparwood monitoring site.

*Note: Water quality guidelines, such as the ones for aquatic health and drinking water, are not based on levels where adverse impacts on health have been reported. They are used as a signal threshold at which monitoring and mitigation strategies should be implemented to decrease the risk of adverse effects on aquatic life or human health.

Does swimming in the Elk River selenium pose a risk to people’s health?

Mammals, including humans, are far less sensitive to selenium compared to fish or other organisms (such as birds) which feed on aquatic plants and insects. Most of the selenium intake in humans comes from diet and dietary supplements and is not absorbed through the skin. According to the BC Ministry of Environment’s Ambient Water Quality Guidelines for Selenium Technical Report Update (2014, pg. 93, section 7.1.1.1) “Selenium compounds are not easily absorbed through the skin; there is little information concerning systemic effects of dermal exposure to Se compounds in humans”. Because selenium is not easily absorbed through the skin, It is highly unlikely that swimming in the Elk River would cause negative effects from exposure of skin to selenium.

Does Elk River selenium pose a human risk for drinking water?

BC Source Drinking Water guideline levels for selenium are 10 µg/L

Health Canada’s Guidelines for Canadian Drinking Water Quality 50 µg/L

Currently, the Elk River selenium concentrations by the Sparwood monitoring site frequently exceed the BC drinking water guideline—however, serious effects from drinking the water are unlikely. According to the Government of Canada, the adult recommended daily intake of selenium is 45 µg, with the Tolerable Upper Intake Level (highest levels where adults are unlikely to experience adverse effects) being 400 µg (see link). At current average Sparwood concentrations in the Elk River (~10 µg/L) an adult would need to drink 4 liters of river water to reach their recommended intake and 40 liters to exceed the Tolerable Upper Intake Level. So far, selenium levels in the Elk River do not exceed Canadian Drinking Water Quality Guidelines of 50 µg/L. Therefore, consuming small amounts of river water is unlikely to cause problems. Selenium concentrations notwithstanding, drinking untreated water from the river is highly discouraged.

Is Elk Valley tap water safe to drink?

Fernie gets most of its water supply from Fairy Creek, and tributary creeks have considerably lower selenium concentrations (~0.5 µg/L) as they are not typically affected by mining. During rare occasions when the water supply from Fairy Creek is not sufficient, a water well in James White Park is used for water. According to the City of Fernie, there have been no exceedances of selenium concentrations during regular drinking water monitoring.

Sparwood gets its water supply from three wells. When monitoring showed that one of the wells had selenium concentrations above the BC drinking water guideline at certain times of the year, a new well was installed and the well with exceedances was shut down. Concentrations of selenium at all current water supply wells are consistently below the drinking water guideline and monitoring data show that the wells have little connectivity to the Elk River or Michel Creek (see District of Sparwood website for more information).  

Elkford uses water wells for its water supply. ERA has not yet received a response about Elkford drinking water testing.  

In other locations in the RDEK Area A: Elk Valley residents outside of municipal water systems typically get their water from groundwater wells, and selenium levels will vary depending on location. If you get your water from a private water well, testing your water for quality (for all potential contaminants) is recommended. See the Health Canada website on water testing for more information.

Are Elk River fish safe to eat?

Fish populations in the Elk Valley are under strain of multiple human stressors (forestry, mining, urban pollution, agriculture, climate change). Westslope cutthroat trout in most locations in the Elk Valley are catch-and-release only. ERA strongly encourages all anglers to practice responsible catch-and-release to preserve this important population of the species.  

Where fish consumption is permitted (for certain species, at certain locations in the watershed), the effect of selenium on dietary safety depends on how much fish you consume. The BC Ministry of Environment Water Quality Guidelines, outlines “screening values” which are thresholds at which health monitoring should be undertaken. These thresholds are designated based on the concentration of selenium in fish tissues, as well as the daily fish consumption amounts. The selenium screening value for people who have a high fish intake (220 g/day, about one fish steak per day) is 7.3 mg/kg (dry fish muscle weight). The screening selenium concentration for people who have a low fish intake (30 g/day, one fish steak every week) is 75 mg/kg. The Regional Aquatic Effects Monitoring Program report  published by Teck in 2020 shows that the concentration of selenium in Westslope cutthroat trout muscle tissue in mine-affected creeks is on average ~8 mg of selenium per kg of dry muscle tissue (i.e., mg/kg) and up to 13 mg/kg in some locations (see Table F.1). Based on these numbers, occasional consumption of Elk Valley fish from mine-affected streams would not exceed the screening values, however daily consumption may exceed screening values. Mountain Whitefish typically have lower concentrations of selenium (see Table F.5) and the body tissue selenium concentration of Westslope cutthroat trout in non-mine-affected streams is considerably lower: 4.36±0.55 mg/kg as reported in Kuchapski and Rasmussen (2015) and an average of 1.29 mg/kg as reported by Henderson and Fischer (2012) (see MOE Water Quality Guidelines). Even high, subsistence level, fish consumption in non-mine-affected creeks is unlikely to trigger screening value thresholds.

Currently there are no selenium-based fish consumption advisories in British Columbia.

How does high selenium impact fish health?

1. Selenium “bioaccumulates” in animal tissues:
   • Small organisms, such as benthic invertebrates (aquatic insects, worms, etc.) absorb selenium in their tissues.
   • Fish eat many insects and thereby accumulate selenium in their own body.
2. As females lay eggs, the high selenium concentration in their body results in fish eggs with a high selenium content. 
3. High selenium concentration in fish eggs interferes with fish development, and effects have been reported at relatively low water selenium concentrations of 5-10 µg/L in laboratory tests (Lemly, 2002). Hatching time, developmental rate, hatchling survival, and hatchling deformities are some of the effects present in waters with increased selenium concentrations.

What are symptoms of selenium toxicity in fish?

• Swelling/Inflammation of gills
• Spinal Deformities
• Edema (swelling due to fluid buildup)
• Deformations of the mouth and jaw
• Pathological alterations of livers, kidneys, hearts, and ovaries
• Eye deformations (including cataracts and protruding eyes)
• Reproductive disruption including lack of fertilization, lower hatchability, and higher mortalities of eggs and young fish
• Anemia

What are some mitigation measures that are taken by the mining industry to decrease selenium concentrations?

The main goal of mitigation strategies is either to take out selenium after it enters the watershed or, preferentially, to design waste rock piles in ways that prevent selenium leaching into the watershed in the first place. Some actions that can “cut selenium off at the source” include:

*End-dumping is the process of backing a dump truck to the valley edge and dumping it, allowing the rocks to roll down. This also causes large plumes of dust.

Water treatment is the other primary approach to selenium mitigation. Teck has active water treatment plants at their Line Creek and Fording River South locations. Teck is also using a method called “saturated rock fill”. Saturated rock fills are constructed in mine pits and are kept filled (saturated) with selenium-rich water gathered and pumped from other areas in the mine.  Being covered with water keeps the rock-filled area low in oxygen. Additional nutrients are added to the rock fill to “boost” the activity of microbes needed to convert mobile selenium to less mobile selenium. The Elkview Saturated Rock Fill has been operational since 2018. Teck is currently commissioning another saturated rock fill at their Fording River North location.   

Teck reports that its treatment facilities are achieving about 95% removal of selenium as well as nitrate from treated water. Total water volumes treated by both active treatment and saturated rock fill facilities are currently 46.5 million gallons per day. Teck states that it is seeing reductions in selenium and nitrate downstream in Line Creek. See the Teck Resources website for details (link here).

Reductions in selenium concentrations elsewhere in the Elk River system (e.g., Fording River) are not yet apparent according to information provided by the Elk Valley Monitoring Committee (see water quality poster Figure 5); however these data pre-date the commissioning of the Fording River South treatment plant. Given the large volume of legacy waste rock piles at Teck’s mining operations, it is not surprising that the relatively recent commissioning of treatment facilities has not yet produced a substantial, or consistent, reduction in selenium concentrations.   

North Coal, who is planning a mining operation around Michel Creek (just north of Hwy 3 in the Crowsnest Pass) has plans to actively and passively mitigate selenium pollution to be in compliance with the Elk Valley Water Quality Plan. According to the North Coal website and personal communications, North Coal’s plans to mitigate selenium concentrations include:

What are “Saturated Rock Fills”?

Saturated rock fills are constructed in mine pits once mining has been completed.  A completed mine pit is filled with waste rock and then allowed to fill (saturate) with rain and snowmelt.  Being covered with water keeps the rock-filled area low in oxygen.  Additional nutrients are added to the rock fill to “boost” the activity  of the naturally-occurring microbes present in the rock fill that convert mobile selenium to less mobile selenium.  The less mobile selenium will stay within the rock fill.  Selenium-rich water is gathered and pumped to the rock fill and left for a period of time until tests show selenium removal has occurred.  The treated water is then pumped out of the rock fill.

What more can be done?

The key to evaluating the success of mitigation strategies is rigorous monitoring of water quality and assessment of mitigation strategies in a collaborative and transparent manner. Unfortunately, much of the uncertainty over the concentrations and effects of selenium on Elk River stem from insufficient monitoring and lack of data sharing. In 2022 the Elk River Alliance released a discussion document on Proposed Approach for Coal Mining Effluent Regulation [link]. In it we provide several recommendations for improvements to mining effluent management: