Blue Green Algae

Environmental Health / Licensing

Blue Green Algae

Blue-green algae, also known as cyanobacteria, are a group of photosynthetic bacteria that people sometimes refer to as "pond scum." Blue-green algae generally grow in lakes, ponds and slow-moving streams when the water is warm and enriched with nutrients like phosphorus or nitrogen.

When blue-green algae float to the water surface they form floating mats which is called a "blue-green algae bloom." In Wisconsin, blue-green algae blooms generally occur between mid-June and late September, although in rare instances, blooms have been observed in winter, even under the ice.

This fact sheet can help you tell blue-green algae apart from their non-harmful look-alikes.

Click here for up to date satellite images of cyanobacteria algal blooms in Green Bay and Lake Winnebago. 

Here's how you can protect your family from Blue-Green Algae:
Protect your family from BGA_1

Protect your family from BGA_2

Blue Green

Health Department
100 Main Street, Suite 100
Menasha, WI 54952
Phone: 920-967-3520
Fax: 920-967-5247

Office Hours:
Monday - Friday
8:00 am - 4:00 pm

Todd Drew, RS