By Heather Brown

MINNEAPOLIS (WCCO) — Ever notice a funky smell around the lakes this time of year? Kind of like rotten eggs?

Jan from New Brighton did earlier this week and wrote to us wanting to know why. Good Question.

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On the north side of the lake inside Columbia Heights’ Kordiak Park, it smells a bit like, as one passerby noted, “Old Faithful.”

So, we brought in lake expert Jim Cotner from the University of Minnesota to find the culprit.

“There’s some bacteria that grow in the lake,” Cotner said.

(credit: CBS)

That bacterium breathes in the sulfates that are in the decaying plants at the bottom of the lake.

“It’s Thanksgiving for them,” he said.

That bacterium then turns those sulfates into smelly sulfide.

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“So what happens in the springtime is the snow melts and the water starts flowing out of the lake, and as it flows out, it’s basically full of that sulfide,” he said.

He said inhaling too much can be hazardous, but frequent walks around smelly lake are harmless.

Cotner said sulfates are randomly distributed in our lakes, so many don’t get stinky at all.

But what does that funk have to say about a lake’s quality?

“One of the big things it says that you have a really productive lake,” Cotner said.

Which makes sense, because Kordiak Park’s lake is urban and shallow.

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The smell typically goes away within a few weeks. When the snow and ice break up more, the sulfide leaves and oxygen comes in, making it smell-free. Consider it just another sign of spring.

Heather Brown