HOW FOREST FIRES CAN IMPACT WATER QUALITY AND DRINKING WATER TREATMENT
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By Michelle Moore
Forest fires can negatively affect water quality, say researchers from the University of Alberta's Southern Rockies Watershed Project team who have been studying the impacts of forest fires on water for about fifteen years.
As of August 14, there were 566 wildfires in British Columbia, resulting in a province-wide state of emergency being declared on August 15. The province may decide to renew or rescind that order in the coming days.
This reporter spoke to the co-lead researchers of The Southern Rockies Watershed Project team to discuss how streams, rivers, water quality, and drinking water treatability may have been affected.
Co-leader of the research and Director of the Water Science, Technology and Policy Group at the University of Waterloo Dr. Monica Emelko, said fluctuations in water quality like those seen after wildfires can lead to increased operational challenges and water treatment costs for municipalities.
Dr. Emelko said "what fires do, is not only can they result in elevated dissolved organic carbon, especially during high flows, or high discharge conditions, but they also result in more aromatic or hydrophobic carbon, which can lead to increased coagulant and oxidant demand, and also lead to a greater potential to form disinfection byproducts."
She explained that conventional water treatment facilities with chemically-assisted filtration are well equipped to remove particles, suspended solids and the contaminants like heavy metals and regulate pH which may be necessary after wildfires.
The more difficult aspect for them is to achieve the correct appropriate coagulant dosing when met with increasingly variable and rapidly changing elevated levels of organic carbon.
Dr. Emelko said, "it might mean something as simple as not being able to meet water demand because you're chasing coagulant dosing and if we can't get it right that could lead to sub optimal filter performance." These challenges can also lead to boil water advisories.
Dr. Uldis Silins co-leads the research and is a hydrologist at the University of Alberta. He explained that forest fires can result in snow pack melting earlier in the season which can lead to very large impacts on water quality for streams and rivers.
Silins said "much higher sediment production, production of nutrients in the water, a bunch range of trace elements," can occur, and last for a long time after a fire.
In their research on the 2003 Lost Creek fire in Alberta for instance, while nitrogen levels recovered after five or six years, Dr. Silins said sediment production remains elevated and they have seen no recovery in phosphorus levels at all.
High levels of nutrients in streams can lead to an increase in productivity, but if there are too many nutrients streams can become mesotrophic or even eutrophic, which can result in algal blooms and oxygen depletion.
The team is also working with Parks Canada concerning the Kenow Mountain fire at Waterton Lakes National Park and has been conducting research in Fort McMurray, Alberta since the fires in 2016.
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