What caused pink & purple slime to appear in Buffalo Run of Big Spirit Lake?

SPIRIT LAKE, Iowa (KUOO) - A bright pink and purple slime found on the water in the Buffalo Run area of Big Spirit Lake was likely a byproduct of a recent heavy algae bloom. That’s according to Mike Hawkins, a fisheries biologist with the Iowa Department of Natural Resources.

“A lot of blue-green algae that had bloomed out on the lake had been concentrated into that area. Kind of a real thick layer of blue-green algae that was decaying and that purple sulfur bacteria took advantage of the situation and bloomed,” said Hawkins in an interview with KUOO Radio. “We don’t see large areas of it like that very commonly but that’s what it was and no danger to that. Purple sulfur bacteria is just simply a sign of a low oxygen condition right there in that decaying mass of organic material.”

Hawkins said algae blooms have been very heavy in many areas this summer due largely to the weather conditions.

“I think a lot of it has to do with really high water temperatures and some fairly stagnant weather conditions with little to no wind that caused those large blooms to occur out on the lake and then subsequently blow into the shoreline,” explained Hawkins.

He also said it’s a sign we need to continue to work on reducing nutrients getting into the lakes.

“We have a lot of phosphorous in the lakes that’s loaded in over the last 100 or so years and we’ve got to continue to work on those practices that we know that work: keeping soil in its place, reducing inputs of nutrients to the lakes as best we can with shoreline protections and making sure that any waste products are managed correctly,” said Hawkins.

The water in the affected area is expected to improve but it’s going to take a little time for the process to complete itself.

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