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This article was published 28/9/2017 (265 days ago), so information in it may no longer be current.
Concerned about the RM of Killarney-Turtle Mountain’s plans to address the abundance of algae in Killarney Lake, Diane Orihel is urging they proceed with caution.
Last week, Mayor Rick Pauls said the municipality planned to install a large-scale aeration unit to tackle the lake’s longstanding algae problem. At a cost of approximately $100,000, he said the goal was to get the project done next spring.
This week, Orihel — a Queens University national scholar in aquatic ecotoxicology — said that although she’d like to back up her concern with hard data, all the information she has gathered so far points to the municipality’s plan not working.
Where aerators have been successfully deployed to limit algae growth in some bodies of water, it’s not a one-size-fits-all solution, Orihel said. Killarney Lake does not fit the mould in a few ways.
In more amicable lakes, aeration stirs up iron sediments, which strips phosphorous out of the water thereby preventing the growth of algae.
Having taken water and sediment core samples from Killarney Lake a few years ago, Orihel said that the iron concentrations appear too low to make this effort a success.
Orihel has also incubated the Killarney samples to both oxic (meaning with oxygen) and anoxic (without oxygen) conditions, revealing higher returns of phosphorous in anoxic conditions.
In conditions where there are two layers of water — the top layer oxic and the bottom layer anoxic — aeration might work well.
Killarney Lake, however, is too shallow to form two layers and is therefore oxic from surface to the lake bed.
"You’re going to add air, but there’s already oxygen in the water column, so what are you really achieving by adding aeration?" she asked. "I’m not convinced that’s going to work in Killarney Lake."
In addition to in all likelihood failing to solve the algae problem, Orihel said that most troubling part in the aeration plan is its potential to stir up a toxic substance that has settled to the bottom of Killarney Lake.
People had been dumping copper sulphate into Killarney Lake for use as an algaecide for a good chunk of the 20th century.
Also called "bluestoning," this practice continued sporadically, and for some stretches annually, until the mid-90s.
Approximately five years ago, Orihel took several samples of Killarney Lake sediment to measure, among other things, copper levels.
The sediment quality guidelines for the protection of aquatic life allows for up to 35 mg/kg dry weight of copper sulphate. While the "probable effect levels" or levels considered toxic to aquatic life is 197 mg/kg.
At Killarney Lake, she took measurements of between 200 and 600 mg/kg, and she said that measurements exceeded the probable effects level "even at the surface."
"What do you think is going to happen when you disturb the bottom of that lake with an aerator?" she asked.
It might not be the "quick fix" or the "silver bullet" solution that some people might want, but Orihel said that the long-term solution to Killarney Lake’s algae problem will be preventing phosphorous from coming in from the watershed.
This means improving sewage disposal and agricultural practices in the watershed as a whole.
Orihel said that she plans on connecting with Killarney Lake area leadership soon in order to express her concerns, as well as put forward more concrete data.
Last week, Pauls clarified that algae blooms have been an ongoing problem at Killarney Lake for as long as anyone can remember and that the community has already undertaken several efforts to reduce the amount of phosphorous entering the watershed.
Orihel is the lead author of a recent national study that examined data from 70 water bodies across Canada, which found that those in the Prairie provinces carried the greatest conditions for algae blooms.
This article can be read online at dx.doi.org/10.1139/cjfas-2016-0500.
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