If you catch a whiff of something near the lakefront that just stinks, it might be a bit hard to identify among Milwaukee’s buffet of bad smells. But depending on where you’re standing, what time of year it is, and which direction the wind is blowing, there’s a chance you’ll be able to pinpoint what’s causing your nose to wrinkle in disgust.
In the springtime, species of diatom algae proliferate in Lake Michigan, says Ryan Newton, an assistant professor at the UW-Milwaukee School of Freshwater Sciences. “Occasionally when they bloom, they can produce kind of a fishy-ish odor, if you will.”
Then in the summer, another pungent algae called cladophora will wash up on shore and decay in the sun. The Department of Natural Resources calls it a “nuisance algae” for the unsightly masses it creates on beaches. Plus, the algae can trap small lake-dwelling organisms that rot and draw in hungry seagulls who poop everywhere.
As for the stink, people often confuse the smell of cladophora with sewage. “[If] you get a big pile of that and the wind is just right, all of a sudden our phones light up,” says Bill Graffin, the public information manager for the Milwaukee Metropolitan Sewerage District.
But it’s not always cladophora. You might also be smelling regular old sewage. The Jones Island Water Reclamation Facility treats wastewater near the south end of the Hoan Bridge, so you might catch a whiff of decaying waste.
Sewage is known to produce a rotten egg smell as it’s digested by invisible microbes. Once microbes are done eating the waste at the Jones Island facility, they die and are turned into a sludge that becomes the fertilizer Milorganite, which has its own earthy scent.
“When it smells like sewage, and there’s very light wind … and you’re driving over the Hoan, it’s probably the plant,” Graffin says. “But when you throw in the wind and other variables and factors, you can’t always say that it is.”
This year, too, there was another culprit causing terrible smells. Small, silvery fish called alewives – invasive to Lake Michigan – appeared to die off in larger quantities than normal this summer. You may have seen them wash up on the beach or pile together in putrid, decaying masses near the lakeshore, though not in enormous quantities like they did in the 1960s and ’70s. In those times, bulldozers were needed to remove mountains of dead fish.
Thankfully though, decaying organisms and even wafting sewage aren’t typically dangerous, says Newton. “At this sort of concentration … they shouldn’t have any harmful effects on anyone other than smell.” And like all wastewater treatment plants, the facility on Jones Island adheres to federal, state and local regulations to make sure it’s not emitting toxic gases into the air. But that doesn’t mean a pungent odor won’t be obnoxious. Sometimes all we can do is plug our noses and deal with it.