All Lake Geneva beaches reopen after week of closures due to blue-green algae

After about a week of beach closures in Lake Geneva due to dangerous blue-green algae, the city announced in a Facebook post that all beach swimming restrictions have been lifted as of Friday morning, just in time for Labor Day weekend.

On Aug. 23 and 24, Lake Geneva's six beaches were closed for swimming due to the presence of blue-green algae , a bloom that can produce toxins that can make humans and animals sick, or even cause them to die in some cases.

On Tuesday, the Williams Bay and Fontana beaches reopened. Now, the Riviera, Big Foot Beach, Town of Linn and Linn Pier Road beaches have reopened as well.

What is blue-green algae?

According to the Walworth County Department of Health and Human Services, "Blue-green algae are photosynthetic bacteria known as 'cyanobacteria,' which can cause illness and death in humans and animals. Blue-green algae are a natural part of lake ecosystems, and algal blooms have occurred for many centuries.

"Algal blooms occur when conditions are right. Little wind, warm water, sunlight and plentiful nutrients, especially phosphorus, all increase the chance that a bloom will happen. Blue-green algae will follow sunlight and nutrients by floating to the surface, where they can form thick scum layers or matts and the surface may look bubbly or frothy. Algal scums can be pushed to different locations by wind."

Not all algal blooms produce toxins, and larger blooms have the potential for higher concentrations of toxins. However, there's no way to immediately know whether a bloom is dangerous or not ― a laboratory test, which takes multiple days, is required. Harmless blooms can also become more toxic and toxic blooms can become harmless over time.

According to the Wisconsin Department of Health Services, blue-green algae exposure can cause the following symptoms in humans: Sore throat, congestion, cough, wheezing, difficulty breathing, eye irritation, itchy skin, red skin, hives, blisters, earache, agitation, headache, abdominal pain, diarrhea and vomiting.

This article originally appeared on Milwaukee Journal Sentinel: All Lake Geneva beaches reopen after week of closures due to blue-green algae