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A geologist looks out at the area of the Red Chris Mine site.

Selenium levels have doubled in fish samples taken from Ealue Lake near the Red Chris copper mine in northwestern British Columbia, raising concerns about a naturally occurring chemical element that can be toxic to aquatic life.

The source of the selenium pollution hasn't been determined and the levels are not high enough to pose a human-health concern. But selenium can cause deformities or reproductive failure in fish and that is raising alarms in the small native community of Iskut, near the mine operated by Imperial Metals.

"Until further tests are done by the mine … we are advising you to not fish in Ealue Lake & at this point suggesting Eddontenajon [Lake] as well," Iskut band councillor Jodi Payne wrote in a recent Facebook posting. "I don't want to cause a huge panic right now, just know we have been made aware and made this a priority to assure it gets dealt with ASAP."

Ms. Payne declined comment when contacted, saying any statements would have to come from the Tahltan Central Government, which responded to questions by issuing a news release.

The TCG, which has invested in the mine and is jointly monitoring the mine's environmental performance with Imperial Metals, said a community meeting will be held to "answer questions regarding selenium levels and provide information about what Tahltan environmental oversight is with regard to the safety of our fish and the health of our Tahltan members."

The statement said selenium and other potential contaminants are being tested for in fish both inside and outside the Red Chris area.

"A previous fish tissue sampling program found that selenium levels in fish were acceptable and represented naturally occurring levels which are not harmful to individual health," stated the TCG.

Selenium occurs naturally in the environment but can be increased to dangerous levels when developments expose sulphur-bearing rocks and soil.

A spokesman for Imperial Metals said the Red Chris mine, which opened in 2015, is not the source of increased selenium in Ealue Lake because the open-pit copper and gold mine drains into a different watershed.

"The fish that were sampled in Ealue Lake were not downstream of the Red Chris mine," said Steve Robertson, vice-president of corporate affairs. "The water from the mine site never actually gets to Ealue Lake."

But a selenium spike has occurred in Ealue Lake since the mine opened. He said tests in 2012 showed selenium levels at 7.3 milligrams per kilogram of dry weight. By 2015, a year after the mine began operating, the level had climbed to 13.4 mg/kg.

"The rise in the number in selenium in fish tissue is a significant difference between 2012 and 2015, but the level of selenium there is still not a concern in terms of consumption for human health," Mr. Robertson said. "There was some concern obviously in the community and perhaps some overreaction. … Those fish are still safe for normal human consumption. … We will continue to monitor this as we go forward but there is no need for concern at this point."

Ken Rabnett, an independent fisheries consultant who works in the region, said a possible source of the selenium could be a mine access road that was cut into a slope above Ealue Lake.

He said if road construction disturbed selenium-bearing rock, pollutants would have drained into the lake.

Asked about that possibility, Mr. Robertson replied: "Yeah, there's potential for that but I would suggest that's highly unlikely because the level of disturbance with that access road is very tiny."

In an e-mail, David Karn, a spokesman for the B.C. Ministry of Environment, said the selenium data from Ealue Lake tests are being reviewed with the Tahltan government to determine how best to address the issue.

"The ministry will be discussing this with the relevant health authorities over the next few weeks regarding consumption of these fish," he wrote.

Mr. Karn said Red Chris is responsible for monitoring and making annual reports to government on selenium levels in water, sediment and aquatic organisms around the mine site.

"Ealue Lake has limited potential to be impacted by the mine as it is not within the drainage area of the mine's tailings impoundment or waste rock storage area," he stated.

Heather Hardcastle, of Salmon Beyond Borders, an Alaska-based organization concerned about pollution flowing across the border from B.C. mines, said the elevated selenium levels appear to be linked to the Red Chris development.

"It's extremely disappointing, although not unexpected," she said. "We will continue to watch this closely."

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