Algae blooms hitting Illinois waters, but potential threat to humans is small

After a delay caused by cooler water temperatures, slimy blue-green algae that can cause a host of health problems is starting to creep into metro-east ponds and small lakes.

Symptoms of the colorful yet potentially toxic slurry include “rashes, hives, diarrhea, vomiting, coughing, or wheezing,” according to the Illinois Department of Public Health.

But, before anyone buys an extra air conditioner and stays indoors all summer, Fred Cronin, a fish biologist at Horseshoe Lake, advises that people understand what’s in the water first.

Big bodies of water, like Horseshoe or Carlyle Lake, are unlikely to have major issues with algae blooms because they have good water flow, washing out the nitrogen and phosphorus from fertilizer runoff that algae feed on before they accumulate. But smaller ponds and lakes that are more stagnant are prime real estate for those nutrients, he said.

Urban areas can trace the issue to a few sources, Cronin said, including yard fertilizer, too many waterfowl and malfunctioning septic systems.

“One of the worst culprits is lawn care services,” Cronin said, pointing a finger at what he said was their habit to spray lawns too heavily.

This year, the algae season has been slow coming, due to cooler temperatures in the water. Cronin said it usually starts when the water gets to 60 degrees, and that happened only recently. Usually, metro-east water is around 80 degrees by now, but Cronin said it’s at around 70.

The Belleville Parks & Recreation Department treats for algae blooms, but there haven’t been too many, Assistant Director Jason Poole said.

A few years ago, some residents complained that there was some algae building up in one of the ponds in Bicentennial Park, but the water in question was clean, Poole said. Instead, workers from the Sewer Department found that a different pond had an algae bloom. The IEPA told the city not to treat it because it would release more toxins than what the algae had already contaminated the water with, so the city posted signs to keep out of the water and let the bloom run its course.

In any case, Poole said, Belleville does not allow any swimming, boating or skating in city parks, so the risk to public health should be minimal.

In addition to Bicentennial Park, Belleville also monitors and treats algae blooms in Bellevue Park, South Side City Park and North Gateway Municipal Park, Poole said.

At Lake Carlyle, algae blooms don’t pose a problem for beachgoers, though the lake does get small blooms from time to time due to crop fertilizer runoff, said Joseph Smothers, who works with the U.S. Army Corps of Engineers, which manages the lake.

“Some years are better than others” for algae, he said, although this year it doesn’t look out of the ordinary, he said.

The Corps tests throughout the summer, usually on a Wednesday before the weekenders arrive, and the tests have all been above state standards, Smothers said. There aren’t many problems near beaches, he added, because they’re open areas with steady wind that churns the water, stopping nutrients from building up.

It may not seem that way to swimmers, stepping on some spinach-like plants, but, as Smothers reminds people, “You’re not swimming in a chlorine pool ... you’re swimming in a living organism.”

In addition to public bodies of water, of course, toxic algae also forms in private bodies of water, such as subdivision lakes and ponds. The city doesn’t keep track of the issue there, Poole said, but there are some ways to treat it.

“In small farm ponds, a copper-based algaecide may be used by owners for treatment of algae,” wrote Kim Biggs of the IEPA.

“However, in larger bodies of water, that would not necessarily be recommended,” she wrote. “While copper can kill algae, the decaying algae causes oxygen to be consumed, and a total loss of oxygen in the water can cause a fish kill. Copper, if applied routinely and over many years, can get into lake sediments and be taken up by fish.”

Copper-based algaecide is a common product in farm supply stores, said Cronin, the fish biologist, but it’s important to know what algae you’re facing first.

There are two types of common algae. The first, called “filamentous” algae, grows earlier than the second kind, called “planktonic,” the toxic blue-green algae the IEPA warned about.

As pond water warms over the course of the summer, it becomes more difficult to treat planktonic algae blooms because warmer water has less oxygen, Cronin said. Mixing in algaecide, which depletes oxygen, may lead to a fish kill.

But some undesirable wet green plants may not be algae at all.

In Bicentennial Park, Poole said, the algae is actually duckweed, a floating weed with a root that dips a half-inch underwater. People confuse the two all the time.

This story was originally published June 2, 2016 at 1:40 PM with the headline "Algae blooms hitting Illinois waters, but potential threat to humans is small."