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When Is It Safe to Swim in Madison’s Lakes?

Posted on June 11, 2025   |   Updated on September 30, 2025
Ava Wojnowski

Ava Wojnowski

Two people swimming in a lake during sunrise.

UW-Madison students swim in Lake Mendota during the summer. (Jeff Miller / University of Wisconsin-Madison)

Summer has arrived and thankfully, Madison is a great place to go swimming with the many lakes the city has to offer. On the City Cast Madison podcast today, Alisa Sleep of the Madison Family parenting site shares some of her favorite places to take a dip.

City Cast

Dive into Madison’s Best Swimming Spots

00:00:00

But there are a few things to keep in mind before diving in.

🏊 Before You Swim

The City of Madison constantly checks the safety of the water in our lakes. For updated information on each beach, you can check with Public Health Madison & Dane County to see what beaches and lakes are open for swimming. While the city tries to be as accurate as possible, conditions can change quickly. This means you should still keep an eye out for green-blue algae in the water.

⚠️ What Exactly is Blue-Green Algae?

Now, you may wonder what exactly you’re looking for when it comes to blue-green algae. The city describes it as “algae that looks blue-green, green, reddish-purple, or brown, murky looking water that has a texture similar to ‘pea soup,’ a layer of scum or puffy blobs floating on the surface, and a strong musty odor near the water.”

Coming into contact with blue-green algae can cause skin irritation, nausea, respiratory problems, and more. The importance of being smart is key when it comes to swimming in these lakes!

If you do come into contact with the blue-green algae, make sure to wash off immediately.

🐶 Note for Dog Owners

Dogs are more affected by the blue-green algae because they're smaller than humans. Make sure to keep an eye on where your dog swims and if they ingest any water. Also, make sure to wash off your dog after they swim in a body of water that may have the blue-green algae.

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