Veterans Park lagoon along Milwaukee’s lakefront is one of the places people gravitate to fish, canoe and kayak. But over the last couple of years, concerns about tenacious toxic algae has raised public health concerns.
Just to be clear, there are all sorts of algae — plants that can range in size from microscopic to massive. Many aren’t toxic, but the type of blue-green algae researchers are monitoring in the lagoon is toxic.
It’s called microsystis, and it can make people sick. If someone swallows the green-tinged lagoon water when the algae are blooming, it could cause flu-like symptoms, rashes, or respiratory distress.
Keeping Watch
Aboard an aluminum fishing boat, Zilber School of Public Health researcher Todd Miller recently walked UWM undergrad Wilson Tarpey through the monitoring process. The student scooped up a water sample from the lagoon's surface, then used a gray-colored metal cylinder called a Van Dorn to grab the water sample.
"When he lowers the sampling device ... the pad on the bottom will trigger the release of the closure mechanism so that we get a discreet sample of water from the bottom of the lagoon only," Miller says.
He started sampling the lagoon's water in 2015. In 2017, the algal bloom was so intense that organizers canceled a popular waterski show and an annual dragon boat festival picked up and moved.
Miller's team increased monitoring to three times a week this summer. He says toxicity levels forced the canoe business to shut down at least once.
Milwaukee’s health department has been keeping tabs on the lagoon’s health — so is Milwaukee County since the lagoon is located within its parks system. In September, county leaders decided to try aerating the lagoon.
A crew installed a bright yellow “curtain” to separate the southern-most end from the north. Miller says four aerators created a gentle current in the south end.
“This kind of algae … are buoyant. They like to stay near the surface and that mixing can sometimes pull the algae from the surface where there’s not enough light for them to grow,” he explains.
Miller says fellow scientists added their expertise.
“Ryan Newton’s lab will be looking at changes in microbial diversity, another scientist will be looking at changes in the amount of organic matter and nutrients, and then we’ll be looking at changes in toxin production from the algae — again on the aerated side compared to the nonaerated side,” he says.
In a healthy aquatic ecosystem, life — even at the microbial level — is abundant and diverse. But Miller says toxic blue-green algae are throwing off that healthy balance and it’s happening in lakes throughout Wisconsin. In fact, it’s a global problem.
The toxic algae thrive when fed by nutrients like phosphorus. High levels enter streams and lakes upstream, off agricultural fields, and downstream off paved surfaces.
What's Next
Miller hopes his findings combined with that of colleagues will become a public health tool that can predict when toxic algae will bloom. But he calls the modeling a coping mechanism, not a solution.
“We can’t control blooms except through nutrient abatement strategies, so reducing the amount of stormwater runoff, the amount runoff from agricultural fields that bring large amounts of phosphorus and nitrogen,” Miller says.
Last week, he finished sampling Veterans Park lagoon for the season. Miller and his students are busily crunching the data they’ve gathered and will pass it along to Milwaukee County. He hopes to be in the lagoon sampling again next season, but that's not all.
“We have an opportunity to do something really cool and unique,” Miller says.
Beyond the lagoon, pavement sends blue-algae-feeding nutrients into the lagoon on stormy days. Miller envisions deep-rooted plants in between the lagoon and the neighboring busy roadway.
"Divert the stormwater into a green space, a bioswale, [to] slow down that storm water and let it just trickle into the lagoon and in process pull out some of the nutrients that are causing algal blooms,” he explains.
Soon the toxic blue-green algae will sink to the lagoon bottom. Some will die, but Miller says some remains dormant, then floats to the surface, ready to grow once again.
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