Tackling increased algae blooms in Lake Winnipeg due to phosphorous runoff needs to be a co-ordinated effort, advocates say.
More and more blue-green sludge has washed up on the banks of Lake Winnipeg in recent years, threatening the health of both the lake’s aquatic species population and the water supply.
Lake Winnipeg’s watershed spans one million square kilometres with various sources polluting it, including contaminants from the Red River, the Saskatchewan River, the Dauphin River, municipal wastewater treatment plants, urban lawns and gardens, and agricultural runoff.
Inoka Amarakoon, assistant professor in the department of soil science at the University of Manitoba, said better nutrient management is the only way to control and prevent increased blooms.
“Phosphorus is a really valuable nutrient. And also it can be a contaminant or deteriorate water quality if it is transported in excess to surface waters,” she said.
Limiting and regulating activity that generates a surplus of the nutrient in waterways, like agriculture runoff and human and animal waste, can go far in preventing elevated phosphorous levels, Amarakoon added.
Within Winnipeg, the sewage treatment plant in the city’s North End has been struggling to comply with limits on phosphorous production, which is pegged at one milligram per litre.
Earlier this month the City of Winnipeg’s water and waste department said there are months in which the treatment plant is in compliance with allocated phosphorous levels. In other months the plant is not.
The waste from the plant is sent into the Red River, which dumps into Lake Winnipeg.
Capital projects to address shortcomings are in the works, the department said.
Amarakoon said phosphorous pollution is coming from across the borders, too, and a collective effort is needed.
“That’s why it’s very complex. Because if it is a single point, it’s easy to control. But it’s very diffuse and multiple jurisdictions,” she said.
“To control the phosphorus, it can be a collective effort in reducing all those sources coming into the lake.… It needs everybody working together to get the concentration down.”
On the western banks of Lake Winnipeg, the East Interlake Watershed District is working with farmers to combat the pollution by working with agricultural soil.
Armand Belanger, manager of the EIWD, said the district is partnering with landowners to do regenerative projects, which turn soil from concrete to sponge.
“One of the best ways to mitigate phosphorus from moving off the soils is to keep the water in the soils. And the best way to do that is to regenerate (it),” he said.
Keeping soil covered, turning it regularly and keeping roots in the ground longer increases the health of the soil so much so it can absorb an inch of rain within minutes.
Regenerating soil also has a cost benefit to farmers as land that retains more water is easier to grow on, Belanger said.
Doing so also means less flooding on farmland.
“So right away, that farmer has a better crop for the field. And it’s more resistant to things like droughts and floods, which we are going to see more with climate change,” Belanger said.
— with files from Katherine Dornian
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