U.S. scientist urges action to save Lake Winnipeg

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This article was published 28/04/2019 (2078 days ago), so information in it may no longer be current.

As Manitobans look forward to spending summer days by the province’s inland sea, they probably aren’t imagining what it would look like dead.

The scientist who saw pollution kill Lake Erie and what brought it back to life hopes the same thing won’t happen to Lake Winnipeg but fears that it might if steps aren’t taken soon.

“It is in a state where time is of the essence to reduce nutrient loading to it,” University of Michigan engineering professor and Great Lakes Water Authority researcher Prof. Glen Daigger said. Excess phosphorus — a nutrient that promotes plant growth — is linked to potentially toxic algae blooms on Lake Winnipeg.

Winnipeg’s north end sewage treatment plant contributes 600 kilograms of phosphorus to the Red River every day that ends up in Lake Winnipeg, the foundation that invited Daigger to speak at its annual general meeting Tuesday evening says. The environmental engineer, researcher and author in Ann Arbor, Mich., said he will talk about ways to dramatically cut the amount of phosphorus in wastewater being pumped into the lake every day.

The Lake Winnipeg Foundation and the International Institute for Sustainable Development have been advocating for the city to use ferric chloride to reduce the phosphorous in the wastewater by 426 kg per day — close to 70 per cent.

“What they’re talking about is something that’s been practiced in the Great Lakes and around the world going back decades,” said Daigger, who has literally written the book on wastewater treatment.

“Chemical phosphorus removal was applied for all the tributaries to the Great Lakes and is one of the major factors that resulted in the restoration of water quality then,” he said.

“Lake Erie was declared to be dead and the effort that restored Lake Erie was one of my inspirations,” Daigger said. He grew up on a hog farm in the U.S. and said he knows Winnipeg’s sewage treatment plant is just one source of the phosphorus ending up in Lake Winnipeg, with agricultural runoff being another.

Undertreated city sewage contributes just five per cent of the phosphorus entering the lake but it’s one source of the problem that can readily be solved, advocates say. The environmental benefits of a $1.8-billion upgrade to Winnipeg’s north end sewage treatment plant are still a decade away, but the city can act now to cut the amount of harmful phosphorus that ends up in Lake Winnipeg, they say.

The City of Winnipeg already uses ferric chloride — a type of iron salt — during the treatment process to reduce odour and keep pipes clean. The Lake Winnipeg Foundation and the International Institute for Sustainable Development are pushing the city to adjust the timing and dose of ferric chloride in the treatment process to use it as a phosphorus-removal agent.

Adding the chemical at an early stage would convert phosphorus in Winnipeg’s wastewater into particles that could be removed during the clarification and digestion processes, proponents say.

The city says it’s looking at the proposal but its environmental licence does not allow for the use of chemicals for removing phosphorus.

“There’s not a magic bullet that’s going to make all of these problems go away,” Daigger said by phone from Michigan. People need the facts to make informed decisions and he’s sharing what he knows at Tuesday night’s meeting.

“These are difficult things for communities to deal with,” he said.

carol.sanders@freepress.mb.ca