Reports of Blue-Green Algae Returning to Some Wisconsin Lakes

Thursday, June 25th, 2026 -- 8:00 AM

(Wisconsin Radio Network) It’s a return of an unhealthy sight on Wisconsin lakes: blue-green algae.

According to the Wisconsin Radio Network, recent sunny days following heavy rains have bloomed algae across southern Wisconsin, including on Madison’s Lake Monona. The D N R says fertilizer and other runoffs can prompt the blooms of single cell plants, and winds easily move the resulting slime into piles on the shore.

Some of that algae can be toxic, so just keep out of the water if you see it and keep pets out of the water as well to prevent serious illness.

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