Lake Winnipeg has earned a disturbing new title from the Global Nature Fund (GNF), as the Threatened Lake of 2013.
"That this huge Canadian lake is faced with problems similar to those of lakes in more densely populated countries is hard to believe," stated the organization, which is based in Berlin, Germany.
"This is the red flag," said Vicki Burns, outreach co-ordinator at the Lake Winnipeg Foundation.
Burns, along with other experts, say blue-green algae is poisoning the lake.
"They're getting so big you can see it from a satellite from outer space," Burns said.
According to the GNF, nutrients and pesticides found in agricultural run-off and sewage discharge are partly responsible for causing the toxic algae.
"It's a consequence of our lack of responsibility to take care of the environment …and the only thing I can say is it can only get worse," said John Werring, senior science and policy advisor at the David Suzuki Foundation.
To restore the lake the pollutants will have to be removed from the water, which Burns said could take decades and could cost millions of dollars.
But the cost of not doing anything could be more devastating — a dead lake.
"I don't want people to think there's no hope for Lake Winnipeg," Burns said. "There's lots of hope and we know quite a few things we can do to turn this around. We've just got to get going and start doing them."
A lake in Peru held the title last year, and one in Columbia in 2011.