Mid Lake Protection & Managment District


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Algae Bloom – Week of July 8th

July 10 @ 8:00 am - 5:00 pm

Some residents recently expressed concern regarding the algae bloom happening on the lake currently. Luckily the lake district has some great contacts at the Wisconsin DNR and they were able to get back to us in less than a day regarding pictures that were sent.

Following is the information we received from the Statewide Harmful Algal Bloom Coordinator and Inland Beach Monitoring Coordinator, Gina LaLiberte:

“You are seeing some sort of filamentous green algae in Mid Lake. These algae are not hazardous so testing is not necessary. They begin to grow near the bottom in cool, clear water in early spring. As the algae photosynthesize they make oxygen, which can form bubbles within the clumps of filaments and lift them to the water’s surface where they form the floating mats in your photos. The strands of algae may feel slippery if you pick them up with your hand – that means they are most likely Spirogyra or a relative. You can also do the “stick test” illustrated on the second page of this DHS algae fact sheet to confirm that they are filamentous green algae.

Filamentous green algae do not make toxins and are not harmful. However, since they can serve as a surface for bacteria to grow and can create stagnant micro-habitats, vey localized areas with high bacteria levels can exist around accumulations of filamentous green algae, so it’s best to swim in areas away from these accumulations.

When filamentous green algae reach the floating mat part of their life cycle, they will start to decompose and become smelly. Depending on wind direction and strength, this accumulation might or might not decompose in the location in your photo.

Runoff from the frequent heavy rains this year may be playing a part in why you are seeing more of this compared to other years. If water levels are up, property owners should be sure they are pumping out and otherwise maintaining their septic systems on recommended schedules. Short ice duration during the past winter might be playing a role. And if winds have been primarily out of the west, that may be helping algae to accumulate and/or stay in place along the east shore.”

Follow the links in blue or see the attached items for identification.

p01888-Staying Safe and Healthy in Wisconsin’s Lakes-What you need to know about blue green algae




July 10
8:00 am - 5:00 pm