‘A one-two punch of heavy rainfall followed by really hot weather’: Research explains algae blooms

‘A one-two punch of heavy rainfall followed by really hot weather’: Research explains algae blooms

It seems like clockwork – it’s early summer, and algae, including the toxic blue-green variety, is taking over Madison lakes, already closing several area beaches so far this summer.

University of Wisconsin-Madison researchers are learning more about what causes the blooms and why they appear so bad this year.

“It just looks kind of gross, and it smells pretty bad as well,” UW-Madison junior Peter Janssen said.

When visiting Lake Mendota, Janssen, who is from Verona, is used to seeing green: the kind of green that makes him think twice before taking a dip.

“I might jump in real quick and get out as fast as I can,” he said.

“Visually, aesthetically, probably the worst-looking blooms we’ve seen in 30 years,” said Chris Kucharik, Professor of Agronomy and Environmental Studies at UW-Madison.

While Kucharik says it’s hard to quantify if the magnitude of the algae is worse this year, he and other researchers are now pinpointing what leads to bigger blooms.

“We have a feeling what’s been happening the last three weeks is related to a one-two punch of heavy rainfall followed by really hot weather,” he said.

Kucharik said that heavy rainfall carries phosphorus, responsible for algae growth, from farmland into the lakes.

Phosphorus also comes from other sources, including urban runoff and stream beds where it’s built up over the years.

That’s what the new Suck the Muck project from Dane County is tackling. Its aim is to clean up sludge containing phosphorus, about 870,000 pounds worth of the nutrient, from 33 miles of streams feeding into the lakes.

“We’ve never done this before,” said John Reimer, Dane County’s Assistant Director of Land and Resources. “It’s been a challenge, but at this point, things are moving really efficiently.”

“Suck the Muck will probably help, I think, temporarily,” Kucharik said, but for long-term results, he believes more would have to be done.

“I think it’s really going to require a transition in agriculture and how we manage land, but we need to help farmers to do that,” he said.

Kucharik said if we see heavy rainfall followed by hot temperatures yet this summer, more big blooms are likely.

“Things will probably end up getting worse before they can get better,” he said.

In a city where green lakes have become the norm, Janssen is still hoping for clearer waters.

“When you go up north, the lakes are clean and nice, so something like that would be better,” he said.