Experts warn of possible high bacteria levels in swimming areas after rainfall

RACINE, Wis. (CBS 58) – With the sun out Monday, many took advantage of the beach after storms hit the Milwaukee area over the weekend.

Experts say those who do go to the beach after rainfall should be cautious, because the water may have increased levels of bacteria, which can cause illness. They say higher levels of bacteria flow into Lake Michigan after rainfall, because storm water collected from streets, yards and driveways gets released into the lake without being treated first. That collection of water sometimes has traces of animal or even human waste.

Dozens spent their Monday at Racine’s North Beach ready to soak up the sun.

“I love the storms, but it's nice to have a little sun too, it gets a little depressing sometimes,” says Olivia Reitzenstein of Racine.

"I don't mind if it storms while I’m at work, but while I’m off I like these beautiful days,” Nicole Coughlin of Racine says.

Julie Kinzelman with Racine's Public Health Department, says their beaches are tested five days a week for a strain of E.coli

"The E.coli that's in the intestines of warm blooded animals and people -- what we're looking for, to see is there any feces... any waste that could be associated with sewage or human waste? That's what we're measuring,” said Kinzelman, Lab Director at Racine Public Health Department.

Beaches with lots of public use are required by the DNR to test more often. After a big storm or rainfall, some beaches post advisories warning people to stay away from the water.

"Some places will have preemptive rainfall advisories, so they'll say if you have an inch of rain, or more than a half inch of rain, we recommend not swimming for a certain period of time," said Kinzelman.

Advisories are not uncommon. Milwaukee's McKinley Beach was under advisory 41% of the year in 2018.

Racine is unique. Kinzelman says they're the first in the country to have real-time test results. Milwaukee's Health Department says their water testing can take up to 18 hours in some cases.

"We’re able to test in near real time. We can tell you whether or not the water's safe, so when we get the sample at 7 o’clock, by 10 o'clock we know whether or not people can swim," adds Kinzelman.

Beaches will have signs posted for water quality marked green, yellow and red.  Green is safe, yellow means there's a risk of illness, and red means stay out of the water.

To check beach conditions in your area before swimming, click here.