Casino Creek runs naturally high in copper near the site of a not-yet-built mine in the Yukon. But just downstream, more than 99 per cent of the copper disappears, far more than could be accounted for by dilution.

Someone or something is cleaning the water and — at the moment — doing it completely free of charge.

Palmer Environmental Consulting Group, Casino Mining Corporation and their partners at Simon Fraser University are hoping to harness this mysterious natural process to protect the environment around the planned copper, gold, molybdenum and silver mine. Contaminated water may have to be treated for 100 years after a mine is exhausted to protect the environment, a major expense for mining companies.

Casino, Palmer and Genome B.C. have put together at $100,000 study to identify and describe scientifically the best candidate for the creek’s mysterious power: bacteria, probably a whole diverse community of microbes that all support the process.

Chris Kennedy, a professor of biology and toxicology at SFU, will help hunt for naturally occurring copper-eating microbes that may be cleaning the water, microbes that could be employed to clean the mine’s effluent.

“If the data shows that some organisms are linked to roles in copper depletion, or to the ability to survive and grow in the presence of high metal concentrations, a natural remediation process may already be present for removal of metal contamination,” Kennedy said.

Water from Proctor Gulch — a headwater tributary to Casino Creek — runs through the mineral deposit in the mine site target area and contains concentrations of copper not unlike those seen in mine run-off, said aquatic ecologist May Quach, a partner with Palmer Environmental.

Over four years, Palmer collected water quality samples that showed the concentration of copper dropped steadily from a high of 0.8 milligrams per litre to just 0.006 mg/l along the 15-kilometre length of Casino Creek.

“Not all the copper is accounted for by dilution,” she said. “We are seeing (copper levels) that are orders of magnitude higher, coming down close to the Canadian water quality guideline.”

Kennedy planted perforated tubes filled with beads along the creek bed to collect “biofilm,” the naturally-occurring bacteria and single-celled organisms that live in the creek. By analyzing genetic material from the biofilm samples, he hopes to comes up with a set of copper-eating candidates or even an entire community of different bacteria that somehow work together to clean the metal from the water.

Some bacteria are able to transform metals such as copper in ways that limit its toxicity and impact on other living things, said Kennedy.

The genetic profile of the bacterial community will be compared against a database of known bacteria in order to “highlight their ability to tolerate or biotransform copper, or tolerate high metal and low pH conditions.”

If a community of copper-eaters can be identified, the next step is to determine whether their power can be harnessed by cultivating them in filter cells or holding ponds full of metal-rich effluent from the mine, work that is being pioneered here in B.C.

Imperial Metals is already engaged in a pilot project to reduce sulphate pollution using microbes on an industrial scale.

Plans for the Casino mine call for passive water treatment through wetlands, but Quach hopes the current study will yield additional tools for purification.

rshore@vancouversun.com

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